A new staphylococcal sigma factor in the conserved gene cassette: functional significance and implication for the evolutionary processes
A new staphylococcal sigma factor in the conserved gene cassette: functional significance and implication for the evolutionary processes
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DOI：
10.1046/j.1365-2443.2003.00668.x
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发表时间：
2003-08-01
期刊：
影响因子：
2.1
通讯作者：
Ohta, T
中科院分区：
文献类型：
--
作者：
Morikawa, K;Inose, Y;Ohta, T
背景：金黄色葡萄球菌是一种主要的人类病原体，由于获得性多重耐药性而导致严重的医院感染。与大肠杆菌和枯草芽孢杆菌等经过充分研究的细菌分别具有 7 个和 18 个 σ 因子不同，金黄色葡萄球菌仅具有 2 个 σ 因子。我们通过检查金黄色葡萄球菌基因组来寻找可能的 sigma 因子基因，特别关注近亲枯草芽孢杆菌 sigma 因子基因周围的基因排列。结果：在葡萄球菌中鉴定出一个新的 sigma 因子基因。该基因与其他基因（包括翻译和转录相关基因）构成保守基因簇。系统发育分析和物种间基因序列比较表明葡萄球菌sigma因子起源于枯草芽孢杆菌SigH的共同祖先。金黄色葡萄球菌中该 sigma 因子的过度表达导致了编码自然遗传能力所需蛋白质的共操纵子表达的急剧诱导。结论：我们证明新鉴定的葡萄球菌 sigma 因子参与了控制遗传能力基因的转录调控网络。在我们的系统发育树中，该因子被归类为具有共同功能的单个组。
Background: Staphylococcus aureus is a major human pathogen and causes a serious hospital infection due to the acquired multidrug resistance. Unlike the well-studied bacteria such as Escherichia coli and Bacillus subtilis , which have seven and 18 sigma factors, respectively, only two sigma factors have been known for S. aureus . We searched for possible sigma factor genes by examining the S. aureus genome with a special attention to the gene arrangement around the sigma factor genes of a close relative, B. subtilis .Results: A new sigma factor gene was identified in Staphylococcus . The gene constituted a conserved gene cluster with other genes including translation- and transcription-related genes. Phylogenetic analysis and comparison of the gene sequences among species indicated that the staphylococcal sigma factor originated from a common ancestor of B. subtilis SigH. An over-expression of this sigma factor in S. aureus resulted in a drastic induction of the expression of the com operons that encode proteins required for the natural genetic competence.Conclusions: We demonstrated that the newly identified staphylococcal sigma factor participated in a regulatory network of transcription that controlled the genetic competence genes. In our phylogenetic tree, the factor was classified as a single group with a common function.