TITLE	IS1403 and IS1404: analysis and distribution of two new insertion sequences in Xanthomonas campestris
AUTHOR	Yung-An Lee Department of Biology, Fu Jen Catholic University, Hsin Chuang 24205, Taipei, Taiwan, Republic of China Shu-Ping Chiu Department of Biology, Fu Jen Catholic University, Hsin Chuang 24205, Taipei, Taiwan, Republic of China
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ABSTRACT	A repetitive sequence in Xanthomonas campestris pv. juglandis was identified as a new insertion sequence, IS1403, by nucleotide sequence analysis. A homologous IS, IS1404, was also cloned from X. campestris pv. campestris. Both shared at least 91% identity on a nucleotide level. The sequences had 42-bp terminal inverted repeat sequences with eleven mismatches, and were flanked by 4-bp target site duplications. Comparison of target insertion sites flanking IS1403 and IS1404 revealed no similarities, and the G+C content of the flanking sequences of IS1403 was 45%, but that of IS1404 was 74%, indicating the elements transpose quite randomly and do not prefer A-T-rich regions. IS1403 and IS1404 contained two GTG-initiated open reading frames (orfA and orfB), and orfB was in phase -1 relative to orfA. There was an A6G motif followed by a potential stem-loop structure between two reading frames, which may have promoted a -1 translational frameshift to produce a transframe protein. The deduced amino acid sequences of orfA and orfB contained a potential a-helix-turn-a-helix DNA-binding motif and a D,D(35)E domain of transposases, respectively. Based on the features discussed, IS1403 and IS1404 were placed among the IS3 family with IS407 from Pseudomonas cepacia, IS476 from X. campestris pv. vesicatoria, IS1222 from Enterobacter agglomerans, and ISR1 from Rhizobium lupini. The insertion sequences were widely distributed and existed in multiple copies in most pathovars of X. campestris, but other plant pathogenic bacteria, such as P. syringae pv. apii, P. syringae pv. tabaci, P. syringae pv. glycinea, P. syringae pv. coronafaciens, Erwinia amylovora, E. carotovora, and E. cypripedii, did not contain this insertion sequence based on Southern hybridization tests.
KEYWORD	Erwinia; Insertion sequence; IS1403; IS1404; Pseudomonas; Xanthomonas campestris;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 39 Number 4 October 1998, page 231-239, 9 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China