Conversion and Compensatory Evolution of the γ-Crystallin Genes and Identification of a Cataractogenic Mutation That Reverses the Sequence of the Human CRYGD Gene to an Ancestral State
2007; Elsevier BV; Volume: 81; Issue: 1 Linguagem: Inglês
10.1086/518616
ISSN1537-6605
AutoresOlga Plotnikova, Fyodor A. Kondrashov, Peter K. Vlasov, Anastasia P. Grigorenko, E. K. Ginter, Е. И. Рогаев,
Tópico(s)Yersinia bacterium, plague, ectoparasites research
ResumoWe identified a mutation in the CRYGD gene (P23S) of the γ-crystallin gene cluster that is associated with a polymorphic congenital cataract that occurs with frequency of ∼0.3% in a human population. To gain insight into the molecular mechanism of the pathogenesis of γ-crystallin isoforms, we undertook an evolutionary analysis of the available mammalian and newly obtained primate sequences of the γ-crystallin genes. The cataract-associated serine at site 23 corresponds to the ancestral state, since it was found in CRYGD of a lower primate and all the surveyed nonprimate mammals. Crystallin proteins include two structurally similar domains, and substitutions in mammalian CRYGD protein at site 23 of the first domain were always associated with substitutions in the structurally reciprocal sites 109 and 136 of the second domain. These data suggest that the cataractogenic effect of serine at site 23 in the N-terminal domain of CRYGD may be compensated indirectly by amino acid changes in a distal domain. We also found that gene conversion was a factor in the evolution of the γ-crystallin gene cluster throughout different mammalian clades. The high rate of gene conversion observed between the functional CRYGD gene and two primate γ-crystallin pseudogenes (CRYGEP1 and CRYGFP1) coupled with a surprising finding of apparent negative selection in primate pseudogenes suggest a deleterious impact of recently derived pseudogenes involved in gene conversion in the γ-crystallin gene cluster. We identified a mutation in the CRYGD gene (P23S) of the γ-crystallin gene cluster that is associated with a polymorphic congenital cataract that occurs with frequency of ∼0.3% in a human population. To gain insight into the molecular mechanism of the pathogenesis of γ-crystallin isoforms, we undertook an evolutionary analysis of the available mammalian and newly obtained primate sequences of the γ-crystallin genes. The cataract-associated serine at site 23 corresponds to the ancestral state, since it was found in CRYGD of a lower primate and all the surveyed nonprimate mammals. Crystallin proteins include two structurally similar domains, and substitutions in mammalian CRYGD protein at site 23 of the first domain were always associated with substitutions in the structurally reciprocal sites 109 and 136 of the second domain. These data suggest that the cataractogenic effect of serine at site 23 in the N-terminal domain of CRYGD may be compensated indirectly by amino acid changes in a distal domain. We also found that gene conversion was a factor in the evolution of the γ-crystallin gene cluster throughout different mammalian clades. The high rate of gene conversion observed between the functional CRYGD gene and two primate γ-crystallin pseudogenes (CRYGEP1 and CRYGFP1) coupled with a surprising finding of apparent negative selection in primate pseudogenes suggest a deleterious impact of recently derived pseudogenes involved in gene conversion in the γ-crystallin gene cluster. Cataracts are characterized by opaqueness of all or part of the eye crystallin lens1Francis PJ Berry V Moore AT Bhattacharya S Lens biology: development and human cataractogenesis.Trends Genet. 1999; 15: 191-196Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar and are the most common cause of blindness in the world, with congenital cataracts frequently resulting in blindness or visual impairment in children.2Francis PJ Berry V Bhattacharya SS Moore AT The genetics of childhood cataract.J Med Genet. 2000; 37: 481-488Crossref PubMed Scopus (178) Google Scholar The estimated prevalence is 2.2–2.49 cases per 10,000 live births,3Reddy MA Francis PJ Berry V Bhattacharya SS Moore AT Molecular genetic basis of inherited cataract and associated phenotypes.Surv Ophthalmol. 2004; 49: 300-315Abstract Full Text Full Text PDF PubMed Scopus (219) Google Scholar and ∼50% of all infantile cataract cases are genetic.2Francis PJ Berry V Bhattacharya SS Moore AT The genetics of childhood cataract.J Med Genet. 2000; 37: 481-488Crossref PubMed Scopus (178) Google Scholar Most cases occur as isolated pathologies, but some forms are associated with other abnormalities.4SanGiovanni JP Chew EY Reed GF Remaley NA Bateman JB Sugimoto TA Klebanoff MA Infantile cataract in the collaborative perinatal project: prevalence and risk factors.Arch Ophthalmol. 2002; 120: 1559-1565Crossref PubMed Scopus (47) Google Scholar Although congenital cataracts can be transmitted as a recessive or an X-linked trait, autosomal dominant inheritance occurs most frequently and exhibits both clinical variability and genetic heterogeneity.3Reddy MA Francis PJ Berry V Bhattacharya SS Moore AT Molecular genetic basis of inherited cataract and associated phenotypes.Surv Ophthalmol. 2004; 49: 300-315Abstract Full Text Full Text PDF PubMed Scopus (219) Google Scholar Clinical and molecular genetics studies have led to the identification of multiple candidate disease loci for congenital cataracts. Mutations in genes encoding four specific types of proteins have been described in association with the phenotype of nonsyndromic inherited cataracts. These include members of the α-, β-, and γ-crystallin families5Blundell T Lindley P Miller L Moss D Slingsby C Tickle I Turnell B Wistow G The molecular structure and stability of the eye lens: x-ray analysis of γ-crystallin II.Nature. 1981; 289: 771-777Crossref PubMed Scopus (386) Google Scholar, 6Graw J The crystallins: genes, proteins and diseases.Biol Chem. 1997; 378: 1331-1348PubMed Google Scholar (MIM +123580, +123590, *123610, *123620, *123630, *123631, +600929, +123680, +123690, and *123730), three transcription factors (MAF7Jamieson RV Perveen R Kerr B Carette M Yardley J Heon E Wirth MG van Heyningen V Donnai D Munier F et al.Domain disruption and mutation of the bZIP transcription factor, MAF, associated with cataract, ocular anterior segment dysgenesis and coloboma.Hum Mol Genet. 2002; 11: 33-42Crossref PubMed Scopus (217) Google Scholar [MIM *177075], PITX38Semina EV Ferrell RE Mintz-Hittner HA Bitoun P Alward WL Reiter RS Funkhauser C ack-Hirsch S Murray JC A novel homeobox gene PITX3 is mutated in families with autosomal-dominant cataracts and ASMD.Nat Genet. 1998; 19: 167-170Crossref PubMed Scopus (317) Google Scholar [MIM +602669], and HSF49Bu L Jin Y Shi Y Chu R Ban A Eiberg H Andres L Jiang H Zheng G Qian M et al.Mutant DNA-binding domain of HSF4 is associated with autosomal dominant lamellar and Marner cataract.Nat Genet. 2002; 31: 276-278Crossref PubMed Scopus (234) Google Scholar [MIM *602438]), cytoskeletal protein BFSP210Conley YP Erturk D Keverline A Mah TS Keravala A Barnes LR Bruchis A Hess JF FitzGerald PG Weeks DE et al.A juvenile-onset, progressive cataract locus on chromosome 3q21-q22 is associated with a missense mutation in the beaded filament structural protein-2.Am J Hum Genet. 2000; 66: 1426-1431Abstract Full Text Full Text PDF PubMed Scopus (134) Google Scholar (MIM *603212), and membrane-transport proteins MIP1Francis PJ Berry V Moore AT Bhattacharya S Lens biology: development and human cataractogenesis.Trends Genet. 1999; 15: 191-196Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar (MIM +154050), GJA3 (CX46)11Bassnett S Missey H Vucemilo I Molecular architecture of the lens fiber cell basal membrane complex.J Cell Sci. 1999; 112: 2155-2165Crossref PubMed Google Scholar (MIM *121015), and GJA8 (CX50)12Berry V Francis P Kaushal S Moore A Bhattacharya S Missense mutations in MIP underlie autosomal dominant "polymorphic" and lamellar cataracts linked to 12q.Nat Genet. 2000; 25: 15-17Crossref PubMed Scopus (242) Google Scholar (MIM *600897). Approximately half of all mutations associated with congenital cataracts are located in crystallin genes.13Hejtmancik JF Smaoui N Molecular genetics of cataract.Dev Ophthalmol. 2003; 37: 67-82Crossref PubMed Scopus (74) Google Scholar Crystallins are the major water-soluble structural proteins expressed in the mammalian eye lens and consist of three major families—the α-, β-, and γ- crystallins14Meakin SO Breitman ML Tsui LC Structural and evolutionary relationships among five members of the human γ-crystallin gene family.Mol Cell Biol. 1985; 5: 1408-1414Crossref PubMed Google Scholar—with the γ-crystallin composing up to 40% of the soluble proteins expressed in the lens.15Meakin SO Du RP Tsui LC Breitman ML γ-Crystallins of the human eye lens: expression analysis of five members of the gene family.Mol Cell Biol. 1987; 7: 2671-2679Crossref PubMed Scopus (57) Google Scholar In humans, the γ-crystallin gene cluster is located on chromosome 2q33-q35 and consists of genes CRYGA (MIM *123660; GenBank accession numbers M17315 and M17316), CRYGB (MIM *123670; GenBank accession number M19364), CRYGC (MIM +123680; GenBank accession numbers K03003 and K03004), and CRYGD (MIM +123690; GenBank accession numbers K03005 and K03006)16Brakenhoff RH Henskens HA van Rossum MW Lubsen NH Schoenmakers JG Activation of the γ E-crystallin pseudogene in the human hereditary Coppock-like cataract.Hum Mol Genet. 1994; 3: 279-283Crossref PubMed Scopus (86) Google Scholar (encoding γA-, γB-, γC-, and γD-crystallins, respectively), with cataract-associated mutations in two of these genes (CRYGD and CRYGC) that code for the most abundant γ-crystallin proteins in the lens.17Pande A Pande J Asherie N Lomakin A Ogun O King JA Lubsen NH Walton D Benedek GB Molecular basis of a progressive juvenile-onset hereditary cataract.Proc Natl Acad Sci USA. 2000; 97: 1993-1998Crossref PubMed Scopus (134) Google Scholar Two other γ-crystallin genes—CRYGEP1 (GenBank accession numbers K03007 and K03008) (encoding γE-crystallin) and CRYGFP1 (GenBank accession numbers K03009 and K03010) (encoding γF-crystallin) (both MIM *123660)—are also located in the same cluster. However, in humans, they harbor a stop codon and are considered pseudogenes, whereas, in other nonprimate mammals, these genes appear functional.18Brakenhoff RH Aarts HJ Reek FH Lubsen NH Schoenmakers JG Human γ-crystallin genes: a gene family on its way to extinction.J Mol Biol. 1990; 216: 519-532Crossref PubMed Scopus (73) Google Scholar Cataractogenesis is anticipated to be a strong factor in selection processes of genes for lens proteins; however, very little is yet known about the evolution of different members of γ-crystallin genes, especially in human and primate lineages. We have previously linked nonnuclear polymorphic congenital cataract (PCC [MIM %601286]) to the γ-crystallin gene cluster (CRYG) on the human chromosome 3q33-35 in a large pedigree from a Central Asian population.19Rogaev EI Rogaeva EA Korovaitseva GI Farrer LA Petrin AN Keryanov SA Turaeva S Chumakov I St George-Hyslop P Ginter EK Linkage of polymorphic congenital cataract to the γ-crystallin gene locus on human chromosome 2q33-35.Hum Mol Genet. 1996; 5: 699-703Crossref PubMed Scopus (56) Google Scholar Here, we screened the PCC-affected pedigree for mutations in the CRYGA–CRYGD genes and performed an evolutionary and structural analysis of the mutation and the γ-crystallin gene family. The collection of DNA samples from subjects with PCC was described elsewhere.19Rogaev EI Rogaeva EA Korovaitseva GI Farrer LA Petrin AN Keryanov SA Turaeva S Chumakov I St George-Hyslop P Ginter EK Linkage of polymorphic congenital cataract to the γ-crystallin gene locus on human chromosome 2q33-35.Hum Mol Genet. 1996; 5: 699-703Crossref PubMed Scopus (56) Google Scholar The genomic sequence of human CRYGA–CRYGD genes was obtained from the GenBank database.20Benson DA Karsch-Mizrachi I Lipman DJ Ostell J Wheeler DL GenBank.Nucleic Acids Res. 2006; 34: D16-D20Crossref PubMed Scopus (409) Google Scholar To search for mutations, the protein-coding regions of these genes were amplified by PCR, by use of genomic DNA from probands of the PCC-affected pedigree. Pairs of oligonucleotide primers flanking the exons of human CRYGA–CRYGD genes were designed manually or by Primer3 and were used for PCR amplification and sequencing of the PCR products (primer oligonucleotide sequences are available from the authors on request). PCR was performed for 32 cycles at 94°C for 3 min, with an annealing temperature of 56°C–58°C for 30 s, and at 72°C for 4 min. Each PCR was performed in a volume of 25 μl that contained 10–20 pmol of each primer, 1× reaction buffer, 50 ng DNA, 200 μM dNTP, 2.5–3 mM MgCl2, and 0.2 U Taq polymerase. The PCR products were purified with electrophoresis in a 1% agarose gel, 1× TBE buffer, and the QIAEX II Kit gel extraction kit (QIAGEN). The purified PCR products were sequenced directly with use of an ABI Prism 310 Automated Sequencer with the ABI Prism BigDye Terminator cycle sequencing kits (Applied Biosystems). The C70T mutation in the CRYGD gene was initially found in selected probands by direct sequencing. The presence or absence of the mutation was elucidated further by restriction enzyme–digestion assay in genomic DNA samples from all affected and unaffected family members of the pedigree. To distinguish the genotypes of unaffected and heterozygous individuals for this particular mutation, we designed nucleotide substitutions in one of the primers (reverse int) to create a new site for BpmI-restriction endonuclease in the mutant C70T allele. Exon 2 of the CRYGD gene was amplified by two rounds of PCR with the primers direct ext (5′-GCAGCCCCACCCGCTCA-3′) and reverse ext (5′-GGGTAATACTTTGCTTATGTGGGG-3′) and then with internal primers direct int (5′-AGCCATGGGGAAGGTGAG-3′) and reverse int (5′-AGTAGGGCTGCAGGCTGG-3′). The PCR products were digested for 3–4 h at 37°C with BpmI, and resulting DNA restriction fragments were analyzed on a 7% polyacrylamide gel and were visualized using ethidium bromide staining. In total, we analyzed 54 individuals with cataract and 46 unaffected individuals from the Middle Asian PCC pedigree. In addition, families with obesity from the same genetic isolate (22 individuals) were genotyped. We also tested 512 control chromosomes from white (206 chromosomes from Russians) and mixed white and Mongolian (224 chromosomes from Tatars and 82 chromosomes from Bashkirs) populations. The cataract-associated mutation (C70T) was detected in affected individuals from the PCC-affected pedigree only. To determine nucleotide sequences for ORFs of functional γ-crystallin genes (CRYGA–CRYGD) in primates, we used the PCR oligonucleotide primers based on human sequences or redundant oligonucleotide primers based on macaque, chimpanzee, and human intronic sequences, such that these primers flanked exons 1, 2, and 3. The PCRs and sequencing were performed as described above. The γ-crystallin gene sequences were determined in species of the following primate families: Hominidae (Pan paniscus [pygmy chimpanzee, GenBank accession numbers EF467187, EF467196, EF467205, and EF467214]; Pan troglodytes [chimpanzee, GenBank accession numbers EF467190, EF467199, EF467208, and EF467217]; Gorilla gorilla [gorilla, GenBank accession numbers EF467183, EF467192, EF467201, and EF467210]; Pongo pigmaeus [orangutan, GenBank accession numbers EF467188, EF467197, EF467206, and EF467215]); Hylobatidae (Hylobates lar [gibbon, GenBank accession numbers EF467184, EF467193, EF467202, and EF467211); Cecropithecidae (Macaca mulatta [rhesus monkey, GenBank accession numbers EF467186, EF467195, EF467204, and EF467213]); Cebidae (Lagothrix lagotricha [common woolly monkey, GenBank accession numbers EF467185, EF467194, EF467203, and EF467212]); Ateles geoffroyi [black-handed spider monkey, GenBank accession numbers EF467182, EF467191, EF467200, and EF467209]); and Callitrichidae (Saguinus labiatus [red-chested mustached tamarin, GenBank accession numbers EF467189, EF467198, EF467207, and EF467216]). In addition, we determined gene sequence for the putative pseudogene CRYGFP1 in Pan paniscus (GenBank accession number EF492219), G. gorilla (GenBank accession number EF492217), Pongo pigmaeus (GenBank accession number EF492220), and H. lar (GenBank accession number EF492218). PCR primer oligonucleotide sequences are available from the authors on request. Genomic DNA samples were obtained from Coriell Cell Repositories and from our own collection of primate DNAs. In addition to the sequenced primate genes, we used the sequence information of the γ-crystallin genes from GenBank.20Benson DA Karsch-Mizrachi I Lipman DJ Ostell J Wheeler DL GenBank.Nucleic Acids Res. 2006; 34: D16-D20Crossref PubMed Scopus (409) Google Scholar We also used the information on gene order from completely sequenced mammalian genomes of Monodelphis domestica, Canis familiaris, Mus musculus, and Bos taurus, using the UCSC Genome Browser.21Kuhn RM Karolchik D Zweig AS Trumbower H Thomas DJ Thakkapallayil A Sugnet CW Stanke M Smith KE Siepel A et al.The UCSC Genome Browser database: update 2007.Nucleic Acids Res. 2006; 34: D590-D598Crossref PubMed Scopus (611) Google Scholar The rat genome (Rattus norvegicus) was excluded from the synteny analysis because of a likely error of assembly of the γ-crystallin cluster. A multiple alignment of all sequences was made using the MUSCLE alignment program.22Edgar RC MUSCLE: multiple sequence alignment with high accuracy and high throughput.Nucleic Acids Res. 2004; 32: 1792-1797Crossref PubMed Scopus (26208) Google Scholar We reconstructed the phylogeny of the γ-crystallin genes, using a Bayesean approach as implemented in MrBayes, with 1 million iterations (mcmc ngen=1,000,000 in MrBayes) with the General Time Reversible model.23Ronquist F Huelsenbeck JP MrBayes 3: Bayesian phylogenetic inference under mixed models.Bioinformatics. 2003; 19: 1572-1574Crossref PubMed Scopus (23389) Google Scholar Sequence divergence between genes was estimated using the codeml program in the PAML package.24Yang Z PAML: a program package for phylogenetic analysis by maximum likelihood.Comput Appl Biosci. 1997; 13: 555-556PubMed Google Scholar Exon 1, which encodes 3 aa, was omitted from the phylogenetic analysis. Elsewhere, we established a link between PCC and the cluster of γ-crystallin genes (CRYG) at chromosome 2q33-35 in a large, unique pedigree of a family from a Central Asian population.19Rogaev EI Rogaeva EA Korovaitseva GI Farrer LA Petrin AN Keryanov SA Turaeva S Chumakov I St George-Hyslop P Ginter EK Linkage of polymorphic congenital cataract to the γ-crystallin gene locus on human chromosome 2q33-35.Hum Mol Genet. 1996; 5: 699-703Crossref PubMed Scopus (56) Google Scholar This population of mixed white and Mongolian origin is characterized by tribe ancestry, high endogamy, and complex ethnic genesis. Two inherited monogenic diseases were accumulated in these populations: an autosomal dominant cataract (PCC), with frequency of the mutant gene of ∼0.26%, and autosomal recessive obesity, with frequency of the mutant gene of ∼2.47%.19Rogaev EI Rogaeva EA Korovaitseva GI Farrer LA Petrin AN Keryanov SA Turaeva S Chumakov I St George-Hyslop P Ginter EK Linkage of polymorphic congenital cataract to the γ-crystallin gene locus on human chromosome 2q33-35.Hum Mol Genet. 1996; 5: 699-703Crossref PubMed Scopus (56) Google Scholar, 25Ginter EK Turaeva S Revazov AA Panteleeva OA Artykov OA Medical genetic study of the population of Turkmenia. III. Hereditary pathology in Turkmen Nokhurlis.Genetika. 1983; 19: 1344-1352PubMed Google Scholar, 26Ginter EK Petrin AN Spitsyn VA Rogaev EI An attempt to locate the gene for congenital cataracts using linkage analysis.Genetika. 1991; 27: 1840-1849PubMed Google Scholar The large 7-generation PCC-affected pedigree characterized by high endogamy and a high coefficient of inbreeding (>3%) was selected for the molecular-genetic study. Of the 157 pedigree individuals, 105 had PCC, and DNA samples from 100 members, including 54 affected individuals, were available for mutation analysis of the CRYG cluster (fig. 1). We amplified and sequenced the coding regions of the CRYGA–CRYGD genes and identified a novel nonsynonymous C70T (P23S) mutation in the coding region of exon 2 of the CRYGD gene, which was found to cosegregate with the disease (fig. 2). The presence or absence of the mutation was confirmed by sequence analysis of four affected and four unaffected individuals from the PCC-affected pedigree and then by restriction enzyme–digestion assay (as described in the "Material and Methods" section) of DNA samples from all available members from the PCC-affected pedigree. All affected individuals—but none of the related unaffected individuals from the PCC-affected pedigree or other unaffected, unrelated control individuals—were found to be heterozygous for this mutation. Three common synonymous SNPs in CRYGB (C192T) and CRYGD (T51C and T392C) were also detected. These polymorphic changes, however, showed no cosegregation with PCC in this pedigree. We found no CRYGD C70T cataract-associated mutation in unaffected individuals from the same genetic isolate or in 512 control chromosomes from populations of white or mixed white and Mongolian origin (see the "Material and Methods" section). The data strongly demonstrated that the nonsynonymous C70T (P23S) substitution in CRYGD is the only mutation in the γ-crystallin gene cluster that segregates with PCC. Mutations that have a pathogenic effect when they are harbored in a human gene can be benign in other, sometimes closely related, organisms.27Kondrashov AS Sunyaev S Kondrashov FA Dobzhansky-Muller incompatibilities in protein evolution.Proc Natl Acad Sci USA. 2002; 99: 14878-14883Crossref PubMed Scopus (203) Google Scholar, 28Kern AD Kondrashov FA Mechanisms and convergence of compensatory evolution in mammalian mitochondrial tRNAs.Nat Genet. 2004; 36: 1207-1212Crossref PubMed Scopus (80) Google Scholar Such cases are known as "compensated pathogenic deviations" (CPDs), since it is thought that the deleterious effect of such mutations is neutralized by another, compensatory mutation. Unlike mutations in γ-crystallins described elsewhere, the mutation we describe here also appears to be a CPD, such that the disease-causing variant is found in the normal CRYGD sequence of several wild-type organisms, including one primate (fig. 3).Figure 3.Sequence alignment of γ-crystallins. The primate sequences determined in this study are shown in bold. Only functional genes are shown. Red arrows indicate known pathogenic mutations in CRYGD, and black arrows indicate known pathogenic mutations in CRYGC. Amino acids highlighted in red indicate CPDs, and amino acids highlighted in blue indicate compensatory substitutions for site 23, whereas amino acids highlighted in yellow indicate the likely interaction states that cause a deleterious interaction with S23. The amino acid positions in CRYGD are numbered from a second amino acid, since the first M amino acid (designated in bold) is processed and omitted from the mature polypeptide. Accordingly, the E106A corresponds to E107A as numbered by Messina-Baas et al.48Messina-Baas OM Gonzalez-Huerta LM Cuevas-Covarrubias SA Two affected siblings with nuclear cataract associated with a novel missense mutation in the CRYGD gene.Mol Vis. 2006; 12: 995-1000PubMed Google Scholar The CRYGC mutations are numbered from the first amino acid residue. The sequences include γA- (CRYGA), γB- (CRYGB), γC- (CRYGC), and γD- (CRYGD) functional crystallins from primates (H. sapiens, Pan troglodytes, Pan paniscus, G. gorilla, Pongo pigmaeus, H. lar, Macaca mulatta, L. lagotricha, and A. geoffroyi) and other mammalian species. Sequences for functional γE- (CRYGE) and γF- (CRYGF) crystallins from nonprimate species are also included.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3.Sequence alignment of γ-crystallins. The primate sequences determined in this study are shown in bold. Only functional genes are shown. Red arrows indicate known pathogenic mutations in CRYGD, and black arrows indicate known pathogenic mutations in CRYGC. Amino acids highlighted in red indicate CPDs, and amino acids highlighted in blue indicate compensatory substitutions for site 23, whereas amino acids highlighted in yellow indicate the likely interaction states that cause a deleterious interaction with S23. The amino acid positions in CRYGD are numbered from a second amino acid, since the first M amino acid (designated in bold) is processed and omitted from the mature polypeptide. Accordingly, the E106A corresponds to E107A as numbered by Messina-Baas et al.48Messina-Baas OM Gonzalez-Huerta LM Cuevas-Covarrubias SA Two affected siblings with nuclear cataract associated with a novel missense mutation in the CRYGD gene.Mol Vis. 2006; 12: 995-1000PubMed Google Scholar The CRYGC mutations are numbered from the first amino acid residue. The sequences include γA- (CRYGA), γB- (CRYGB), γC- (CRYGC), and γD- (CRYGD) functional crystallins from primates (H. sapiens, Pan troglodytes, Pan paniscus, G. gorilla, Pongo pigmaeus, H. lar, Macaca mulatta, L. lagotricha, and A. geoffroyi) and other mammalian species. Sequences for functional γE- (CRYGE) and γF- (CRYGF) crystallins from nonprimate species are also included.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3.Sequence alignment of γ-crystallins. The primate sequences determined in this study are shown in bold. Only functional genes are shown. Red arrows indicate known pathogenic mutations in CRYGD, and black arrows indicate known pathogenic mutations in CRYGC. Amino acids highlighted in red indicate CPDs, and amino acids highlighted in blue indicate compensatory substitutions for site 23, whereas amino acids highlighted in yellow indicate the likely interaction states that cause a deleterious interaction with S23. The amino acid positions in CRYGD are numbered from a second amino acid, since the first M amino acid (designated in bold) is processed and omitted from the mature polypeptide. Accordingly, the E106A corresponds to E107A as numbered by Messina-Baas et al.48Messina-Baas OM Gonzalez-Huerta LM Cuevas-Covarrubias SA Two affected siblings with nuclear cataract associated with a novel missense mutation in the CRYGD gene.Mol Vis. 2006; 12: 995-1000PubMed Google Scholar The CRYGC mutations are numbered from the first amino acid residue. The sequences include γA- (CRYGA), γB- (CRYGB), γC- (CRYGC), and γD- (CRYGD) functional crystallins from primates (H. sapiens, Pan troglodytes, Pan paniscus, G. gorilla, Pongo pigmaeus, H. lar, Macaca mulatta, L. lagotricha, and A. geoffroyi) and other mammalian species. Sequences for functional γE- (CRYGE) and γF- (CRYGF) crystallins from nonprimate species are also included.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3.Sequence alignment of γ-crystallins. The primate sequences determined in this study are shown in bold. Only functional genes are shown. Red arrows indicate known pathogenic mutations in CRYGD, and black arrows indicate known pathogenic mutations in CRYGC. Amino acids highlighted in red indicate CPDs, and amino acids highlighted in blue indicate compensatory substitutions for site 23, whereas amino acids highlighted in yellow indicate the likely interaction states that cause a deleterious interaction with S23. The amino acid positions in CRYGD are numbered from a second amino acid, since the first M amino acid (designated in bold) is processed and omitted from the mature polypeptide. Accordingly, the E106A corresponds to E107A as numbered by Messina-Baas et al.48Messina-Baas OM Gonzalez-Huerta LM Cuevas-Covarrubias SA Two affected siblings with nuclear cataract associated with a novel missense mutation in the CRYGD gene.Mol Vis. 2006; 12: 995-1000PubMed Google Scholar The CRYGC mutations are numbered from the first amino acid residue. The sequences include γA- (CRYGA), γB- (CRYGB), γC- (CRYGC), and γD- (CRYGD) functional crystallins from primates (H. sapiens, Pan troglodytes, Pan paniscus, G. gorilla, Pongo pigmaeus, H. lar, Macaca mulatta, L. lagotricha, and A. geoffroyi) and other mammalian species. Sequences for functional γE- (CRYGE) and γF- (CRYGF) crystallins from nonprimate species are also included.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The basis of compensations of CPDs is usually the maintenance of structural stability within a single molecule,27Kondrashov AS Sunyaev S Kondrashov FA Dobzhansky-Muller incompatibilities in protein evolution.Proc Natl Acad Sci USA. 2002; 99: 14878-14883Crossref PubMed Scopus (203) Google Scholar, 28Kern AD Kondrashov FA Mechanisms and convergence of compensatory evolution in mammalian mitochondrial tRNAs.Nat Genet. 2004; 36: 1207-1212Crossref PubMed Scopus (80) Google Scholar, 29Fukami-Kobayashi K Schreiber DR Benner SA Detecting compensatory covariation signals in protein evolution using reconstructed ancestral sequences.J Mol Biol. 2002; 319: 729-743Crossref PubMed Scopus (49) Google Scholar, 30Poon A Chao L The rate of compensatory mutation in the DNA bacteriophage phiX174.Genetics. 2005; 170: 989-999Crossref PubMed Scopus (118) Google Scholar although, in a few cases, the compensatory mutation and the CPD may be located on two different interacting proteins.27Kondrashov AS Sunyaev S Kondrashov FA Dobzhansky-Muller incompatibilities in protein evolution.Proc Natl Acad Sci U
Referência(s)