Popescu Andrei, Karpay Anne, Israel Dawn A, Peek Richard M, Krezel Andrzej M
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37232, USA.
Proteins. 2005 May 1;59(2):303-11. doi: 10.1002/prot.20406.
Helicobacter pylori is a widespread human bacterial pathogen responsible for inducing gastric and duodenal ulcers and gastric cancers. To date, only 16 protein structures from this organism have been determined, and more than 30% of its 1500 protein functions remain unknown. We report the biochemical characterization, the tertiary structure determined by solution nuclear magnetic resonance (NMR) methods and the putative function of the previously uncharacterized protein HP0222 (JHP0208) from H. pylori. Recombinant HP0222 behaves as a dimer in crosslinking and size exclusion chromatography experiments. The structure consists of a ribbon-helix-helix fold characteristic of transcription factors of the Arc/MetJ family, which all bind DNA as higher order oligomers. Electrophoretic mobility shift assays reveal that HP0222 binds to double-stranded DNA. Previous studies have shown significant increases in transcription levels of HP0222 in response to acid shock and adherence to gastric epithelial cells. To assess possible involvement of HP0222 in acid resistance, we constructed and assayed an H. pylori HP0222 null mutant. We propose that HP0222 is a novel transcriptional regulator in H. pylori.
幽门螺杆菌是一种广泛存在的人类细菌病原体，可引发胃溃疡、十二指肠溃疡和胃癌。迄今为止，该生物体仅16种蛋白质结构得以确定，其1500种蛋白质功能中超过30%仍不为人所知。我们报告了幽门螺杆菌中此前未被鉴定的蛋白质HP0222（JHP0208）的生化特性、通过溶液核磁共振（NMR）方法测定的三级结构以及推测的功能。在交联和尺寸排阻色谱实验中，重组HP0222表现为二聚体。该结构由Arc/MetJ家族转录因子特有的带状 - 螺旋 - 螺旋折叠组成，这些转录因子均以高阶寡聚体形式结合DNA。电泳迁移率变动分析表明，HP0222与双链DNA结合。先前的研究显示，响应酸休克和黏附于胃上皮细胞时，HP0222的转录水平显著升高。为评估HP0222可能参与酸抗性的情况，我们构建并检测了幽门螺杆菌HP0222基因缺失突变体。我们认为HP0222是幽门螺杆菌中的一种新型转录调节因子。
