Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis
Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis
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DOI：
10.1074/jbc.m113.533620
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发表时间：
2014-02-28
影响因子：
4.8
通讯作者：
Kitten, Todd
中科院分区：
文献类型：
--
作者：
Rhodes, DeLacy V.;Crump, Katie E.;Kitten, Todd
背景：NrdEF核糖核苷酸还原酶存在于许多细菌病原体中，并在体外与铁或锰辅因子一起发挥作用。结果：缺乏NrdEF或其锰辅因子的血链球菌突变体不能有氧生长或引起心内膜炎。结论：锰辅因子是毒力所必需的。意义：这项工作可以解释为什么许多含NrdEF的细菌需要锰来提高毒力和耐氧性。血链球菌是感染性心内膜炎的一个原因，并已被证明需要锰转运蛋白称为SsaB的毒力和O-2耐受性。与其他病原体一样，S.血吸虫具有需氧Ib类（NrdEF）和厌氧III类（NrdDG）核糖核苷酸还原酶（RNR），其执行将核糖核苷酸还原为脱氧核糖核苷酸的基本功能。随附的论文（Makhlynets，O.，波尔A. K.，罗兹，D.五、Kitten，T.，Rosenzweig，A. C.的方法，和Stubbe，J.（2014）J.Biol.Chem.289，6259-6272）表明，在O-2存在下，S.血吸虫Ib型RNR在体外自组装必需的二铁-酪氨酰自由基（Fe-2（III）-Y-中心点），而二锰-酪氨酰自由基（Mn-2（III）-Y-中心点）辅因子的组装需要NrdI，并且Mn-2（III）-Y-中心点比Fe-2（III）-Y-中心点对NrdH和硫氧还蛋白还原酶（TrxR 1）的内源性还原系统更有活性。在这项研究中，我们已经表明，无论是删除nrdHEKF或nrdI完全废除心内膜炎的动物模型中的毒力，而nrdD突变没有影响。nrdHEKF、nrdI和trxR 1突变体不能有氧生长，而厌氧生长需要nrdD。将编码O-2非依赖性腺苷钴胺素辅因子RNR的nrdJ基因引入nrdHEKF、nrdI和trxR 1突变体中。在O-2存在下，nrdHEKF和nrdI突变体的生长得到部分恢复。综合结果表明，Mn-2（III）-Y-中心点因子NrdF是需要在有氧条件下和动物的生长。这可以部分解释为什么锰在许多具有Ib类RNR的细菌病原体中对于毒力和O-2耐受性是必需的，并且表明NrdF和NrdI可以作为有希望的新的抗菌靶标。
Background: NrdEF ribonucleotide reductases are found in many bacterial pathogens and function in vitro with either iron or manganese cofactors. Results:Streptococcus sanguinis mutants lacking NrdEF or its manganese cofactor cannot grow aerobically or cause endocarditis. Conclusion: The manganese cofactor is essential for virulence. Significance: This work may explain why many NrdEF-containing bacteria require manganese for virulence and oxygen tolerance. Streptococcus sanguinis is a cause of infective endocarditis and has been shown to require a manganese transporter called SsaB for virulence and O-2 tolerance. Like certain other pathogens, S. sanguinis possesses aerobic class Ib (NrdEF) and anaerobic class III (NrdDG) ribonucleotide reductases (RNRs) that perform the essential function of reducing ribonucleotides to deoxyribonucleotides. The accompanying paper (Makhlynets, O., Boal, A. K., Rhodes, D. V., Kitten, T., Rosenzweig, A. C., and Stubbe, J. (2014) J. Biol. Chem. 289, 6259-6272) indicates that in the presence of O-2, the S. sanguinis class Ib RNR self-assembles an essential diferric-tyrosyl radical (Fe-2(III)-Y-center dot) in vitro, whereas assembly of a dimanganese-tyrosyl radical (Mn-2(III)-Y-center dot) cofactor requires NrdI, and Mn-2(III)-Y-center dot is more active than Fe-2(III)-Y-center dot with the endogenous reducing system of NrdH and thioredoxin reductase (TrxR1). In this study, we have shown that deletion of either nrdHEKF or nrdI completely abolishes virulence in an animal model of endocarditis, whereas nrdD mutation has no effect. The nrdHEKF, nrdI, and trxR1 mutants fail to grow aerobically, whereas anaerobic growth requires nrdD. The nrdJ gene encoding an O-2-independent adenosylcobalamin-cofactored RNR was introduced into the nrdHEKF, nrdI, and trxR1 mutants. Growth of the nrdHEKF and nrdI mutants in the presence of O-2 was partially restored. The combined results suggest that Mn-2(III)-Y-center dot-cofactored NrdF is required for growth under aerobic conditions and in animals. This could explain in part why manganese is necessary for virulence and O-2 tolerance in many bacterial pathogens possessing a class Ib RNR and suggests NrdF and NrdI may serve as promising new antimicrobial targets.