Title

Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis

Authors

DeLacy V. Rhodes, Virginia Commonwealth University
Katie E. Crump, Virginia Commonwealth UniversityFollow
Olga Makhlynets, Massachusetts Institute of Technology
Melanie Snyder, Virginia Commonwealth University
Xiuchun Ge, Virginia Commonwealth University
Ping Xu, Virginia Commonwealth University
JoAnne Stubbe, Massachusetts Institute of Technology
Todd Kitten, Virginia Commonwealth University

Document Type

Article

Publication Date

2-28-2014

Publication Title

Journal of Biological Chemistry

Keywords

Bacterial Metabolism, Bacterial Pathogenesis, Manganese, Ribonucleotide Reductase, Streptococcus, Infective Endocarditis

ISSN

0021-9258

Volume

289

Issue/No.

9

First Page

6273

Last Page

6287

Abstract

Streptococcus sanguinis is a cause of infective endocarditis and has been shown to require a manganese transporter called SsaB for virulence and O₂ 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 O₂, the S. sanguinis class Ib RNR self-assembles an essential diferric-tyrosyl radical (Fe^III₂-Y^•) in vitro, whereas assembly of a dimanganese-tyrosyl radical (Mn^III₂-Y^•) cofactor requires NrdI, and Mn^III₂-Y^• is more active than Fe^III₂-Y^• 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 trxR1mutants fail to grow aerobically, whereas anaerobic growth requires nrdD. The nrdJgene encoding an O₂-independent adenosylcobalamin-cofactored RNR was introduced into the nrdHEKF, nrdI, and trxR1 mutants. Growth of the nrdHEKF and nrdI mutants in the presence of O₂ was partially restored. The combined results suggest that Mn^III₂-Y^•-cofactored NrdF is required for growth under aerobic conditions and in animals. This could explain in part why manganese is necessary for virulence and O₂ tolerance in many bacterial pathogens possessing a class Ib RNR and suggests NrdF and NrdI may serve as promising new antimicrobial targets.

NSUWorks Citation

Rhodes, DeLacy V.; Katie E. Crump; Olga Makhlynets; Melanie Snyder; Xiuchun Ge; Ping Xu; JoAnne Stubbe; and Todd Kitten. 2014. "Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis." Journal of Biological Chemistry 289, (9): 6273-6287. doi:10.1074/jbc.M113.533620.

DOI

10.1074/jbc.M113.533620