芒果细菌性黑斑病菌XcmR基因的克隆与序列分析

Cloning and Sequence Analysis of XcmR from Xanthomonas campestris pv.mangiferaeindicae

根据黄单孢菌属LuxR基因的同源性设计简并引物XF／XR,采用同源克隆法从芒果细菌性黑斑病菌（Xanthomonas campestria pv．mangiferaeindicae）中获得了约1．4kb的DNA片段。经测序和序列同源性分析表明．该基因片段长1422bp含有一个完整的LuxR同源基因，并命名为XcmR。生物信息学分析表明．XcmR基因完整ORF（开放阅读框）全长765bp，编码254个氨基酸，分子质量和等电点分别约为28．2ku和8．9，与GenBank中公布的Xanthomonas属LuxR或AhyR／AsaR氨基酸序列具有86％～99％相似性。系统聚类结果表明，XcmR与来源于柑桔溃疡病菌（X．axonopodis pv．citri）、番茄疮痂病菌（X．c．pv．vesicatoria）、水稻白叶枯菌（X．oryzae pv．oryzae）和甘蓝黑腐病菌（X．c．pv．campest如）的LuxR蛋白聚成一支。NCBI网站蛋白质保守结构域搜索表明，XcmR是LuxR蛋白家族的一员，具有LuxR蛋白相似结构。

In this study, degenerate PCR primers XF/XR were designed according to the conserved amino acid sequence of Xanthomonas LuxR family conservative district, and a DNA fragment about 1.4 kb was cloned from Xanthomonas campestris pv. mangiferaeindica using PCR. Sequence analysis extrapolated that the DNA fragment was 1 422 bp, containing a complete LuxR homologue, designated as XcmR. XcmR is a transcriptional factor, containing an 765 bp ORF structure, and encoding a putative protein of 254 bp-amino-acid with Mr=28.2 ku and PI=8.9, and 86%-99% similarity to Xanthomonas LuxR family and AhyR/AsaR. Phylogenetic clustering suggested that the amino acid sequence of XcmR showed high similarity to L.uxR homologs of X. axonopodis pv. citri, X. c. pv. vesicatoria, X. oryzae pv. oryzae and X. c. pv. campestris. Phylogenetic studies revealed that XcmR clustered with Xanthhomnas LuxR family and AhyR/AsaR homologs. Conservative structure domain analysis showed that XcmR had LuxR similar protein structure, belonging to the LuxR protein family.