Lee T C, Lee M C, Hung C H, Weng S F, Tseng Y H
Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan, Republic of China.
J Mol Microbiol Biotechnol. 2001 Oct;3(4):519-28.
The uvrB gene of Xanthomonas campestris pv. campestris, a Gram-negative plant pathogenic bacterium inhabiting soil and infected plants, was cloned and sequenced. This gene has the capacity to encode a polypeptide of 673 amino acid residues with a calculated molecular mass of 75.9 kDa. Its deduced amino acid sequence shows a high degree of similarity and possesses domain conservation to those of bacterial UvrB. The uvrB mutant, isolated by gene replacement, is extremely sensitive to ultraviolet irradiation. Like the situation in the X. campestris pv. campestris recA gene, no SOS box is present upstream of the uvrB gene. Northern blotting and transcriptional fusion assay with lacZ indicated that X. campestris pv. campestris uvrB is expressed constitutively at high levels and cannot be further induced by UV irradiation. These results suggest a regulatory mechanism different from that for the expression of Escherichia coli uvrB. Using a gene-tagging strategy in conjunction with pulsed-field gel electrophoresis, the uvrB gene was located near 1 o'clock on the X. campestris pv. campestris 17 chromosome (4.8 Mb) map, which is far apart from the lexA-recA-recX cluster near 5 o'clock.
野油菜黄单胞菌野油菜致病变种（一种存在于土壤和受感染植物中的革兰氏阴性植物病原菌）的uvrB基因被克隆并测序。该基因能够编码一个由673个氨基酸残基组成的多肽，计算分子量为75.9 kDa。其推导的氨基酸序列与细菌UvrB的序列具有高度相似性并存在结构域保守性。通过基因置换分离得到的uvrB突变体对紫外线照射极为敏感。与野油菜黄单胞菌野油菜致病变种recA基因的情况一样，uvrB基因上游不存在SOS框。Northern印迹法和用lacZ进行的转录融合分析表明，野油菜黄单胞菌野油菜致病变种uvrB持续高水平表达，且不能被紫外线照射进一步诱导。这些结果提示了一种与大肠杆菌uvrB表达调控机制不同的调控机制。利用基因标签策略结合脉冲场凝胶电泳，uvrB基因定位在野油菜黄单胞菌野油菜致病变种17号染色体（4.8 Mb）图谱上接近1点的位置，这与接近5点的lexA-recA-recX簇相距甚远。
