The YjbH Protein of Bacillus subtilis Enhances ClpXP-Catalyzed Proteolysis of Spx
The YjbH Protein of Bacillus subtilis Enhances ClpXP-Catalyzed Proteolysis of Spx
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DOI：
10.1128/jb.01289-08
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发表时间：
2009-02-15
影响因子：
3.2
通讯作者：
Zuber, Peter
中科院分区：
文献类型：
--
作者：
Garg, Saurabh K.;Kommineni, Sushma;Zuber, Peter
枯草芽孢杆菌的全局转录调节因子Spx在基因表达过程的几个水平上受到控制。在不受干扰的生长过程中，它通过ATP依赖性蛋白酶ClpXP维持在低浓度。在二硫化物胁迫下，Spx浓度增加，部分原因是ClpXP催化的蛋白水解减少。最近的研究拉尔森和同事（分子。Microbiol. 66：669-684，2007）暗示yjbH基因的产物是Spx的蛋白水解控制所必需的。在本研究中，酵母双杂交分析和蛋白质-蛋白质交联表明，Spx与YjbH相互作用。显示YjbH蛋白在含有ClpXP蛋白酶但不含ClpCP蛋白酶的反应混合物中增强Spx的蛋白水解。具有残基1至24缺失的YjbH的N-末端截短形式（YjbH（Delta 1-24））显示没有蛋白水解增强活性。YjbH对Spx具有特异性，因为它不加速ClpXP底物绿色荧光蛋白（GFP）-SsrA（一种具有C-末端SsrA标签的GFP衍生物，可被ClpXP识别）的蛋白水解。使用电感耦合等离子体原子发射光谱和4-（2-吡啶偶氮）间苯二酚释放实验，YjbH被发现含有锌原子。YjbH（Delta 1-24）的锌分析表明，N末端富含组氨酸的区域对于至少一个锌原子的配位是不可或缺的。一个锌原子协调的N-末端区域迅速释放的蛋白质处理后，用强氧化剂。总之，YjbH提出了ClpXP催化Spx降解的适配器，并提出了涉及Zn解离的YjbH氧化还原控制模型。
The global transcriptional regulator Spx of Bacillus subtilis is controlled at several levels of the gene expression process. It is maintained at low concentrations during unperturbed growth by the ATP-dependent protease ClpXP. Under disulfide stress, Spx concentration increases due in part to a reduction in ClpXP-catalyzed proteolysis. Recent studies of Larsson and coworkers (Mol. Microbiol. 66: 669-684, 2007) implicated the product of the yjbH gene as being necessary for the proteolytic control of Spx. In the present study, yeast two-hybrid analysis and protein-protein cross-linking showed that Spx interacts with YjbH. YjbH protein was shown to enhance the proteolysis of Spx in reaction mixtures containing ClpXP protease but not ClpCP protease. An N-terminal truncated form of YjbH with a deletion of residues 1 to 24 (YjbH(Delta 1-24)) showed no proteolysis enhancement activity. YjbH is specific for Spx as it did not accelerate proteolysis of the ClpXP substrate green fluorescent protein (GFP)-SsrA, a GFP derivative with a C-terminal SsrA tag that is recognized by ClpXP. Using inductively coupled plasma atomic emission spectroscopy and 4-(2-pyridylazo) resorcinol release experiments, YjbH was found to contain zinc atoms. Zinc analysis of YjbH(Delta 1-24) revealed that the N-terminal histidine-rich region is indispensable for the coordination of at least one Zn atom. A Zn atom coordinated by the N-terminal region was rapidly released from the protein upon treatment with a strong oxidant. In conclusion, YjbH is proposed to be an adaptor for ClpXP-catalyzed Spx degradation, and a model of YjbH redox control involving Zn dissociation is presented.