CtaM Is Required for Menaquinol Oxidase aa3 Function in Staphylococcus aureus.
CtaM Is Required for Menaquinol Oxidase aa3 Function in Staphylococcus aureus.
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DOI：
10.1128/mbio.00823-16
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发表时间：
2016-07-12
期刊：
影响因子：
6.4
通讯作者：
Skaar EP
中科院分区：
文献类型：
--
作者：
Hammer ND;Schurig-Briccio LA;Gerdes SY;Gennis RB;Skaar EP
在发达国家，金黄色葡萄球菌是皮肤和软组织感染、菌血症、骨髓炎和心内膜炎的主要原因。金黄色葡萄球菌在不同宿主环境中引起实质性疾病的能力是由灵活的代谢支持的，这种代谢允许这种病原体克服每个宿主器官特有的挑战。葡萄球菌代谢灵活性的一个特征是由多个末端氧化酶组成的支化有氧呼吸链。尽管之前的生化和光谱研究报道了三种不同的呼吸氧还原酶（o型，bd型和aa3型）的存在，但基因组只包含两种呼吸氧还原酶cydAB和qoxABCD的基因。先前的研究表明，cydAB和qoxABCD分别需要在特定的宿主器官（小鼠心脏和肝脏）定殖。这项工作旨在阐明遗传研究表明cydAB和qoxABCD在毒力和文献中报道的呼吸还原酶中的独特作用之间的关系。我们确定QoxABCD是一种aa3型甲基萘酚氧化酶，但这种酶是混杂的，因为它可以组装成bo3型甲基萘酚氧化酶。然而，bo3形式的QoxABCD限制了支持金黄色葡萄球菌生长的碳源。此外，QoxABCD功能由一种以前未被表征的蛋白支持，我们将其命名为CtaM，该蛋白在有氧呼吸厚壁菌中保守。综上所述，这些研究建立了金黄色葡萄球菌血红素A的生物合成途径，确定了QoxABCD是一种aa3型甲基萘酚氧化酶，揭示了CtaM是多种细菌属中aa3型甲基萘酚氧化酶功能所需的新蛋白。金黄色葡萄球菌依靠两种末端氧化酶CydAB和QoxABCD的功能进行有氧呼吸和定植不同的宿主组织。先前的生物化学研究支持第三种末端氧化酶也存在的结论。我们通过确定与QoxABCD相互作用的血红素辅助因子，建立了金黄色葡萄球菌电子传递链的组分。这一发现解释了之前的观察结果，揭示了QoxABCD可以利用不同的血红素辅助因子，并证实了金黄色葡萄球菌的电子传递链由两个末端甲基萘酚氧化酶组成。此外，一种新发现的蛋白质CtaM被发现是QoxABCD功能所必需的。这些结果为支持葡萄球菌呼吸的分子机制提供了更完整的评估。
Staphylococcus aureus is the leading cause of skin and soft tissue infections, bacteremia, osteomyelitis, and endocarditis in the developed world. The ability of S. aureus to cause substantial disease in distinct host environments is supported by a flexible metabolism that allows this pathogen to overcome challenges unique to each host organ. One feature of staphylococcal metabolic flexibility is a branched aerobic respiratory chain composed of multiple terminal oxidases. Whereas previous biochemical and spectroscopic studies reported the presence of three different respiratory oxygen reductases (o type, bd type, and aa3 type), the genome contains genes encoding only two respiratory oxygen reductases, cydAB and qoxABCD. Previous investigation showed that cydAB and qoxABCD are required to colonize specific host organs, the murine heart and liver, respectively. This work seeks to clarify the relationship between the genetic studies showing the unique roles of the cydAB and qoxABCD in virulence and the respiratory reductases reported in the literature. We establish that QoxABCD is an aa3-type menaquinol oxidase but that this enzyme is promiscuous in that it can assemble as a bo3-type menaquinol oxidase. However, the bo3 form of QoxABCD restricts the carbon sources that can support the growth of S. aureus. In addition, QoxABCD function is supported by a previously uncharacterized protein, which we have named CtaM, that is conserved in aerobically respiring Firmicutes. In total, these studies establish the heme A biosynthesis pathway in S. aureus, determine that QoxABCD is a type aa3 menaquinol oxidase, and reveal CtaM as a new protein required for type aa3 menaquinol oxidase function in multiple bacterial genera. Staphylococcus aureus relies upon the function of two terminal oxidases, CydAB and QoxABCD, to aerobically respire and colonize distinct host tissues. Previous biochemical studies support the conclusion that a third terminal oxidase is also present. We establish the components of the S. aureus electron transport chain by determining the heme cofactors that interact with QoxABCD. This insight explains previous observations by revealing that QoxABCD can utilize different heme cofactors and confirms that the electron transport chain of S. aureus is comprised of two terminal menaquinol oxidases. In addition, a newly identified protein, CtaM, is found to be required for the function of QoxABCD. These results provide a more complete assessment of the molecular mechanisms that support staphylococcal respiration.