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Oligomerization of the telomerase reverse transcriptase from Euplotes crassus

2002; Oxford University Press; Volume: 30; Issue: 18 Linguagem: Inglês

10.1093/nar/gkf513

1362-4962

Liang Wang,

Protist diversity and phylogeny

The telomerase ribonucleoprotein reverse transcriptase uses its RNA subunit as a template to synthesize telomeric repeats and maintain telomere tracts on chromosome ends. In the ciliate Euplotescrassus, the core telomerase ribonucleoprotein particle undergoes a developmentally programmed assembly into three higher order complexes after mating. Here, we provide evidence using oligonucleotide‐directed affinity purification that all of the E.crassus telomerase complexes contain at least two enzyme active sites. Furthermore, we show using co‐immunoprecipitation experiments that EcTERT, the telomerase catalytic subunit, undergoes multimerization in vitro. Two independent interaction domains were identified in EcTERT, one at the N‐terminus that spans amino acids 186–354 and one at the C‐terminus that spans amino acids 755–857. Unexpectedly, we found that TERT can form head‐to‐head, tail‐to‐tail and head‐to‐tail oligomers in vitro, implying that E.crassus telomerase has the potential to assume different conformations in vivo. Together, these data indicate that oligomerization is a conserved feature of telomerase and that the minimal functional unit of the enzyme is a dimer.