The Transcriptional Regulator CpsY Is Important for Innate Immune Evasion in Streptococcus pyogenes

• Published in: Infection and immunity Vol. 85; no. 3
• Main Authors: Vega, Luis A, Valdes, Kayla M, Sundar, Ganesh S, Belew, Ashton T, Islam, Emrul, Berge, Jacob, Curry, Patrick, Chen, Steven, El-Sayed, Najib M, Le Breton, Yoann, McIver, Kevin S
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.03.2017
• Subjects: Animals; Bacterial Infections; Bacterial Proteins - genetics; Disease Models, Animal; Host-Pathogen Interactions - immunology; Humans; Immunity, Innate; Macrophages - immunology; Macrophages - metabolism; Macrophages - microbiology; Mice; Microbial Viability; Mutation; Neutrophils - immunology; Neutrophils - metabolism; Neutrophils - microbiology; Streptococcal Infections - immunology; Streptococcal Infections - metabolism; Streptococcal Infections - microbiology; Streptococcal Infections - mortality; Streptococcus pyogenes - physiology; Transcription Factors - genetics; Virulence; CpsY; immune evasion; human-specific virulence; transcriptional regulation; LysR family regulators
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.00925-16

As an exclusively human pathogen, (the group A streptococcus [GAS]) has specifically adapted to evade host innate immunity and survive in multiple tissue niches, including blood. GAS can overcome the metabolic constraints of the blood environment and expresses various immunomodulatory factors necessary for survival and immune cell resistance. Here we present our investigation of one such factor, the predicted LysR family transcriptional regulator CpsY. The encoding gene, , was initially identified as being required for GAS survival in a transposon-site hybridization (TraSH) screen in whole human blood. CpsY is homologous with transcriptional regulators of (MetR), (CpsY), and (MtaR) that regulate methionine transport, amino acid metabolism, resistance to neutrophil-mediated killing, and survival Our investigation indicated that CpsY is involved in GAS resistance to innate immune cells of its human host. However, GAS CpsY does not manifest the phenotypes of its homologs in other streptococcal species. GAS CpsY appears to regulate a small set of genes that is markedly different from the regulons of its homologs. The differential expression of these genes depends on the growth medium, and CpsY modestly influences their expression. The GAS CpsY regulon includes known virulence factors ( , , , [ ], [ ], and ) and cell surface-associated factors of GAS ( , , [ ], and ). Intriguingly, the loss of CpsY in GAS does not result in virulence defects in murine models of infection, suggesting that CpsY function in immune evasion is specific to the human host.