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Characterization of Insertions of IS 476 and Two Newly Identified Insertion Sequences, IS 1478 and IS 1479 , in Xanthomonas campestris pv. campestris

1999; American Society for Microbiology; Volume: 181; Issue: 4 Linguagem: Inglês

10.1128/jb.181.4.1220-1228.1999

1098-5530

Jiann‐Hwa Chen, Yu-Ying Hsieh, Su-Lian Hsiau, Ta-Chun Lo, Chen-Chun Shau,

Genomics and Phylogenetic Studies

ABSTRACT Thirty-two plasmid insertion mutants were independently isolated from two strains of Xanthomonas campestris pv. campestris in Taiwan. Of the 32 mutants, 14 (44%), 8 (25%), and 4 (12%) mutants resulted from separate insertions of an IS 3 family member, IS 476 , and two new insertion sequences (IS), IS 1478 and IS 1479 . While IS 1478 does not have significant sequence homology with any IS elements in the EMBL/GenBank/DDBJ database, IS 1479 demonstrated 73% sequence homology with IS 1051 in X. campestris pv. dieffenbachiae, 62% homology with IS 52 in Pseudomonas syringae pv. glycinea, and 60% homology with IS 5 in Escherichia coli . Based on the predicted transposase sequences as well as the terminal nucleotide sequences, IS 1478 by itself constitutes a new subfamily of the widespread IS 5 family, whereas IS 1479 , along with IS 1051 , IS 52 , and IS 5 , belongs to the IS 5 subfamily of the IS 5 family. All but one of the IS 476 insertions had duplications of 4 bp at the target sites without sequence preference and were randomly distributed. An IS 476 insertion carried a duplication of 952 bp at the target site. A model for generating these long direct repeats is proposed. Insertions of IS 1478 and IS 1479 , on the other hand, were not random, and IS 1478 and IS 1479 each showed conservation of PyPuNTTA and PyTAPu sequences (Py is a pyrimidine, Pu is a purine, and N is any nucleotide) for duplications at the target sites. The results of Southern blot hybridization analysis indicated that multiple copies of IS 476 , IS 1478 , and IS 1479 are present in the genomes of all seven X. campestris pv. campestris strains tested and several X. campestris pathovars.