Cubero Jaime, Graham James H
University of Florida, Citrus Research and Education Center (CREC), 700 Experiment Station Road, Lake Alfred, FL 33850-2299, USA.
Int J Syst Evol Microbiol. 2004 Mar;54(Pt 2):429-437. doi: 10.1099/ijs.0.02784-0.
Characterization of strains of Xanthomonas axonopodis pv. citri by using DNA fingerprints that were generated from primers for enterobacterial repetitive intergenic consensus (ERIC) elements led to the discovery of differential sequences for a leucine-responsive regulatory protein (lrp) gene in two subgroups of strains with different host ranges on Citrus spp. DNA hybridization and PCR-based assays that used different sets of primers were designed to detect the core sequence, as well as to obtain the entire sequence of the lrp gene for several Xanthomonas species and pathovars. Higher variability was observed at the nucleotide level than at the amino acid level among the different species and pathovars, revealing selection pressure on the lrp gene, which is presumably due to an essential role of the gene in bacterial metabolism. Moderate variability in the 3' and 5' domains was used to study relationships among different species within the genus XANTHOMONAS: Species of this genus that were isolated from citrus, as well as other pathovars of X. axonopodis, showed highly similar lrp gene sequences, whereas other Xanthomonas species, especially Xanthomonas campestris, had sequences that were more dissimilar to that of X. axonopodis. Thus, the lrp gene sequence is useful to distinguish X. axonopodis pv. citri groups and promising for polyphasic taxonomic analysis of the genus XANTHOMONAS: Data from analysis of lrp gene sequences support the current concepts for classification of xanthomonads, which are based on other approaches.
利用从肠杆菌重复基因间共有序列（ERIC）元件引物产生的DNA指纹图谱对柑橘溃疡病菌株进行表征，导致在柑橘属上具有不同寄主范围的两个菌株亚组中发现了亮氨酸响应调节蛋白（lrp）基因的差异序列。设计了使用不同引物组的DNA杂交和基于PCR的检测方法，以检测核心序列，并获得几种黄单胞菌属物种和致病变种的lrp基因的完整序列。在不同物种和致病变种中，核苷酸水平的变异性高于氨基酸水平，这揭示了lrp基因上的选择压力，推测这是由于该基因在细菌代谢中的重要作用。3'和5'结构域的适度变异性被用于研究黄单胞菌属内不同物种之间的关系：从柑橘中分离出的该属物种以及柑橘溃疡病菌的其他致病变种显示出高度相似的lrp基因序列，而其他黄单胞菌物种，尤其是野油菜黄单胞菌，其序列与柑橘溃疡病菌的序列差异更大。因此，lrp基因序列可用于区分柑橘溃疡病菌组，并有望用于黄单胞菌属的多相分类分析：lrp基因序列分析的数据支持基于其他方法的当前黄单胞菌分类概念。
