Petersohn Anja, Antelmann Haike, Gerth Ulf, Hecker Michael
Microbiology (Reading). 1999 Apr;145 ( Pt 4):869-880. doi: 10.1099/13500872-145-4-869.
Bacillus subtilis responds to various stimuli (heat, ethanol and salt stress, energy starvation) with the induction of general stress proteins (GSPs). Most of them belong to the stress and stationary-phase regulon controlled by the alternative sigma factor sigmaB. The majority of sigmaB-dependent proteins are thought to provide a precautionary general stress resistance in stressed or starved cells. In this report, the identification and transcriptional analysis of nine new members of the sigmaB regulon are described. The biochemical function was not determined for any of the proteins encoded by the nine new sigmaB-dependent stress genes, however, similarities to proteins in the databases allowed a distinction between proteins with putative (i-iv) and unknown (v) function. The putative functions of BmrU, YcdF, YdaD, YdaP, YhdN and YocK underline the suggested protective role of sigmaB-dependent GSPs and also elucidate new areas where sigmaB might play an important role. (i) The finding that the bmrUR operon is under sigmaB control indicates that the elimination of multidrug compounds might be a new function in multiple stress resistance. (ii) YcdF and YdaD resemble NAD(P)-dependent dehydrogenases. Both proteins could be involved in the generation of NAD(P)H and therefore in the maintenance of the intracellular redox balance under stress. (iii) The ydaP gene might belong to the increasing number of sigmaB-dependent genes whose orthologues are under the control of sigmas in Escherichia coli, indicating that both regulons may fulfil similar functions. (iv) YhdN shows weak similarities to potassium ion channel proteins and YocK shows resemblance to the DnaK suppressor protein DksA. (v) Three new sigmaB-dependent genes (ydaE, ydaG and yfkM) encoding proteins with still unknown functions were also described. Further analyses of corresponding mutants might allow a first prediction of their function within the framework of the general stress regulon.
枯草芽孢杆菌会通过诱导产生一般应激蛋白（GSPs）来应对各种刺激（热、乙醇和盐胁迫、能量饥饿）。其中大多数属于由替代西格玛因子sigmaB控制的应激和稳定期调节子。大多数依赖sigmaB的蛋白质被认为在受胁迫或饥饿的细胞中提供预防性的一般应激抗性。在本报告中，描述了sigmaB调节子九个新成员的鉴定和转录分析。然而，这九个新的依赖sigmaB的应激基因所编码的任何蛋白质的生化功能均未确定，不过，与数据库中蛋白质的相似性使得能够区分具有推定功能（i - iv）和未知功能（v）的蛋白质。BmrU、YcdF、YdaD、YdaP、YhdN和YocK的推定功能强调了依赖sigmaB的GSPs的保护作用，也阐明了sigmaB可能发挥重要作用的新领域。（i）bmrUR操纵子受sigmaB控制这一发现表明，多药化合物的清除可能是多重应激抗性中的一项新功能。（ii）YcdF和YdaD类似于NAD(P)依赖性脱氢酶。这两种蛋白质可能都参与NAD(P)H的生成，因此在应激状态下维持细胞内的氧化还原平衡。（iii）ydaP基因可能属于越来越多的依赖sigmaB的基因，其直系同源物在大肠杆菌中受sigma因子控制，这表明这两个调节子可能具有相似的功能。（iv）YhdN与钾离子通道蛋白有微弱的相似性，YocK与DnaK抑制蛋白DksA相似。（v）还描述了三个新的依赖sigmaB的基因（ydaE、ydaG和yfkM），它们编码的蛋白质功能仍然未知。对相应突变体的进一步分析可能有助于在一般应激调节子的框架内对其功能进行初步预测。
