Department of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
Arch Microbiol. 2010 Jun;192(6):499-504. doi: 10.1007/s00203-010-0571-y. Epub 2010 May 1.
In many bacterial species, the translational GTPase TypA acts as a global stress- and virulence regulator and also mediates resistance to the antimicrobial peptide BPI. On the chromosome of M. tuberculosis, typA is located next to narGHJI, which plays a role in adaptation of the pathogen to various environmental conditions. Here, we show that Mycobacterium tuberculosis is sensitive to P2, a derivative of BPI. Using a typA mutant of M. tuberculosis, we found this phenotype to be independent of TypA. We further tested typA expression in M. tuberculosis under defined stress conditions, such as oxygen- and nutrient depletion, low pH, heat shock, antibiotic stress and the presence of P2, and found that typA expression remains unaffected by any of these conditions. Analysis of growth and whole-genome expression revealed similar growth kinetics and gene expression profiles of the wild type and the mutant under normal growth conditions as well as under stress conditions. Our results suggest that in contrast to the findings in other bacteria, TypA does not act as a global stress- and virulence regulator in M. tuberculosis.
在许多细菌物种中，翻译延伸因子 GTPase TypA 充当全局应激和毒力调节剂，并且还介导对抗菌肽 BPI 的抗性。在结核分枝杆菌的染色体上，typA 位于 narGHJI 旁边，narGHJI 在病原体适应各种环境条件中发挥作用。在这里，我们表明结核分枝杆菌对 P2（BPI 的衍生物）敏感。使用结核分枝杆菌的 typA 突变体，我们发现该表型与 TypA 无关。我们进一步在结核分枝杆菌中测试了 typA 在特定应激条件下的表达，例如缺氧和营养耗尽、低 pH 值、热休克、抗生素应激和 P2 的存在，并且发现 typA 的表达不受任何这些条件的影响。生长和全基因组表达的分析显示，野生型和突变体在正常生长条件下以及在应激条件下的生长动力学和基因表达谱相似。我们的结果表明，与其他细菌的研究结果相反，在结核分枝杆菌中，TypA 不作为全局应激和毒力调节剂发挥作用。
