Reva Oleg N, Weinel Christian, Weinel Miryam, Böhm Kerstin, Stjepandic Diana, Hoheisel Jörg D, Tümmler Burkhard
Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, D-30623 Hannover, Germany.
J Bacteriol. 2006 Jun;188(11):4079-92. doi: 10.1128/JB.00101-06.
The metabolically versatile soil bacterium Pseudomonas putida has to cope with numerous abiotic stresses in its habitats. The stress responses of P. putida KT2440 to 4 degrees C, pH 4.5, 0.8 M urea, and 45 mM sodium benzoate were analyzed by determining the global mRNA expression profiles and screening for stress-intolerant nonauxotrophic Tn5 transposon mutants. In 392 regulated genes or operons, 36 gene regions were differentially expressed by more than 2.5-fold, and 32 genes in 23 operons were found to be indispensable for growth during exposure to one of the abiotic stresses. The transcriptomes of the responses to urea, benzoate, and 4 degrees C correlated positively with each other but negatively with the transcriptome of the mineral acid response. The CbrAB sensor kinase, the cysteine synthase CysM, PcnB and VacB, which control mRNA stability, and BipA, which exerts transcript-specific translational control, were essential to cope with cold stress. The cyo operon was required to cope with acid stress. A functional PhoP, PtsP, RelA/SpoT modulon, and adhesion protein LapA were necessary for growth in the presence of urea, and the outer membrane proteins OmlA and FepA and the phosphate transporter PstBACS were indispensable for growth in the presence of benzoate. A lipid A acyltransferase (PP0063) was a mandatory component of the stress responses to cold, mineral acid, and benzoate. Adaptation of the membrane barrier, uptake of phosphate, maintenance of the intracellular pH and redox status, and translational control of metabolism are key mechanisms of the response of P. putida to abiotic stresses.
代谢功能多样的土壤细菌恶臭假单胞菌必须应对其栖息地中的多种非生物胁迫。通过测定全局mRNA表达谱并筛选不耐胁迫的非营养缺陷型Tn5转座子突变体，分析了恶臭假单胞菌KT2440对4℃、pH 4.5、0.8 M尿素和45 mM苯甲酸钠的胁迫反应。在392个受调控的基因或操纵子中，36个基因区域的差异表达超过2.5倍，并且发现在暴露于其中一种非生物胁迫期间，23个操纵子中的32个基因对于生长是必不可少的。对尿素、苯甲酸盐和4℃反应的转录组相互呈正相关，但与无机酸反应的转录组呈负相关。CbrAB传感器激酶、控制mRNA稳定性的半胱氨酸合酶CysM、PcnB和VacB以及发挥转录特异性翻译控制作用的BipA对于应对冷胁迫至关重要。cyo操纵子是应对酸胁迫所必需的。功能性的PhoP、PtsP、RelA/SpoT调节子和粘附蛋白LapA是在尿素存在下生长所必需的，而外膜蛋白OmlA和FepA以及磷酸盐转运蛋白PstBACS是在苯甲酸盐存在下生长所不可或缺的。脂质A酰基转移酶（PP0063）是对冷、无机酸和苯甲酸盐胁迫反应的必需组成部分。膜屏障的适应、磷酸盐的摄取、细胞内pH和氧化还原状态的维持以及代谢的翻译控制是恶臭假单胞菌对非生物胁迫反应的关键机制。
