The lone S41 family C-terminal processing protease in Staphylococcus aureus is localized to the cell wall and contributes to virulence

Abstract

Staphylococcus aureus is a versatile pathogen of humans and a continued public health concern due to the rise and spread of multidrug-resistant strains. As part of an ongoing investigation into the pathogenic mechanisms of this organism we previously demonstrated that an intracellular Nterminal processing protease is required for S. aureus virulence. Following on from this, here we examine the role of CtpA, the lone C-terminal processing protease of S. aureus. CtpA, a member of the S41 family, is a serine protease whose homologues in Gram-negative bacteria have been implicated in a range of biological functions, including pathogenesis. We demonstrate that S. aureus CtpA is localized to the bacterial cell wall and expression of the ctpA gene is maximal upon exposure to conditions encountered during infection. Disruption of the ctpA gene leads to decreased heat tolerance and increased sensitivity when exposed to components of the host immune system. Finally we demonstrate that the ctpA " mutant strain is attenuated for virulence in a murine model of infection. Our results represent the first characterization of a C-terminal processing protease in a pathogenic Gram-positive bacterium and show that it plays a critical role during infection.

Regulated, sequential processing by multiple proteases is required for proper maturation and release of Bordetella filamentous hemagglutinin

“…ORF BB0300, annotated as ctpA , is 99% identical to the B. pertussis homolog and predicted to encode a member of the Prc/Tsp/CtpA family of proteases that target C‐termini (Hara et al , ; Silber et al , ; Keiler and Sauer, ). This family has been implicated in a variety of functions in Gram‐negative and Gram‐positive bacteria, including membrane integrity, virulence and photosynthesis (Hara et al , ; Anbudurai et al , ; Keiler et al , ; Ostberg et al , ; Bandara et al , ; Reiling et al , ; Gilbert et al , ; Seo and Darwin, ; Carroll et al , ; Teoh et al , ). B. bronchiseptica CtpA is predicted to possess three domains common to the family: a Sec signal sequence, a target‐binding PDZ domain and a serine‐lysine catalytic dyad (Fig.…”

SosA inhibits cell division in Staphylococcus aureus in response to DNA damage

“…To identify a membrane localized protease that may be responsible for SosA turnover, we searched the Nebraska Transposon Mutant Library (Fey et al , ) for S. aureus protease mutant strains, and as a potential candidate, we identified the carboxyl‐terminal protease A, CtpA. The S. aureus CtpA protein is located at the cell membrane/cell wall fraction and is involved in stress tolerance and virulence in a mouse model of infection (Carroll et al , ). Importantly, overproduction of the WT SosA protein in cells lacking ctpA completely abolished cell viability, similarly to what was observed when the 10‐AA‐truncated SosA protein was expressed in WT S. aureus cells (Fig.…”

An Intracellular Peptidyl-Prolyl cis / trans Isomerase Is Required for Folding and Activity of the Staphylococcus aureus Secreted Virulence Factor Nuclease

“…S. aureus containing this plasmid was grown to stationary phase and protein samples taken representing the intracellular (cytoplasmic), cell wall, and extracellular (secreted) fractions, as previously described (53). These samples were separated by SDS-PAGE, transferred to a PVDF membrane, and probed with an HA epitope tag antibody (Thermo Fisher).…”