Structural insights into RipC, a putative citrate lyase β subunit from a Yersinia pestis virulence operon.

Rodrigo Torres, Nicholas Chim, Banumathi Sankaran, Céline Pujol, James B Bliska, Celia W Goulding

Index: Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 68(Pt 1) , 2-7, (2012)

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Abstract

Yersinia pestis remains a threat, with outbreaks of plague occurring in rural areas and its emergence as a weapon of bioterrorism; thus, an improved understanding of its various pathogenicity pathways is warranted. The rip (required for intracellular proliferation) virulence operon is required for Y. pestis survival in interferon-γ-treated macrophages and has been implicated in lowering macrophage-produced nitric oxide levels. RipC, one of three gene products from the rip operon, is annotated as a citrate lyase β subunit. Furthermore, the Y. pestis genome lacks genes that encode citrate lyase α and γ subunits, suggesting a unique functional role of RipC in the Y. pestis rip-mediated survival pathway. Here, the 2.45 Å resolution crystal structure of RipC revealed a homotrimer in which each monomer consists of a (β/α)(8) TIM-barrel fold. Furthermore, the trimeric state was confirmed in solution by size-exclusion chromatography. Through sequence and structure comparisons with homologous proteins, it is proposed that RipC is a putative CoA- or CoA-derivative binding protein.© 2012 International Union of Crystallography. All rights reserved.