title: An Intracellular Peptidyl-Prolyl cis/trans Isomerase Is Required for Folding and Activity of the Staphylococcus aureus Secreted Virulence Factor Nuclease.
abstract: Staphylococcus aureus is an important human pathogen that relies on a large repertoire of secreted and cell wall-associated proteins for pathogenesis. Consequently, the ability of the organism to cause disease is absolutely dependent on its ability to synthesize and successfully secrete these proteins. In this study, we investigate the role of peptidyl-prolyl cis/trans isomerases (PPIases) on the activity of the S. aureus secreted virulence factor nuclease (Nuc). We identify a staphylococcal cyclophilin-type PPIase (PpiB) that is required for optimal activity of Nuc. Disruption of ppiB results in decreased nuclease activity in culture supernatants; however, the levels of Nuc protein are not altered, suggesting that the decrease in activity results from misfolding of Nuc in the absence of PpiB. We go on to demonstrate that PpiB exhibits PPIase activity in vitro, is localized to the bacterial cytosol, and directly interacts with Nuc in vitro to accelerate the rate of Nuc refolding. Finally, we demonstrate an additional role for PpiB in S. aureus hemolysis and demonstrate that the S. aureus parvulin-type PPIase PrsA also plays a role in the activity of secreted virulence factors. The deletion of prsA leads to a decrease in secreted protease and phospholipase activity, similar to that observed in other Gram-positive pathogens. Together, these results demonstrate, for the first time to our knowledge, that PPIases play an important role in the secretion of virulence factors in S. aureus IMPORTANCE: Staphylococcus aureus is a highly dangerous bacterial pathogen capable of causing a variety of infections throughout the human body. The ability of S. aureus to cause disease is largely due to an extensive repertoire of secreted and cell wall-associated proteins, including adhesins, toxins, exoenzymes, and superantigens. These virulence factors, once produced, are typically transported across the cell membrane by the secretory (Sec) system in a denatured state. Consequently, once outside the cell, they must refold into their active form. This step often requires the assistance of bacterial folding proteins, such as PPIases. In this work, we investigate the role of PPIases in S. aureus and uncover a cyclophilin-type enzyme that assists in the folding/refolding of staphylococcal nuclease.
authors: Department of Biological Sciences, Ohio University, Athens, Ohio, USA.
authors: Richard E
authors: RE
authors: Wiemels
authors: Department of Biological Sciences, Ohio University, Athens, Ohio, USA.
authors: Stephanie M
authors: SM
authors: Cech
authors: Department of Biological Sciences, Ohio University, Athens, Ohio, USA.
authors: Nikki M
authors: NM
authors: Meyer
authors: Department of Biological Sciences, Ohio University, Athens, Ohio, USA.
authors: Caleb A
authors: CA
authors: Burke
authors: Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA.
authors: Andy
authors: A
authors: Weiss
authors: Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA.
authors: Anastacia R
authors: AR
authors: Parks
authors: Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA.
authors: Lindsey N
authors: http://orcid.org/0000-0002-0629-8990
authors: LN
authors: Shaw
authors: Department of Biological Sciences, Ohio University, Athens, Ohio, USA carrolr3@ohio.edu.
authors: Ronan K
authors: http://orcid.org/0000-0001-7090-3414
authors: RK
authors: Carroll
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D009154:Mutation; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors; D019696:Peptidylprolyl Isomerase
keywords: Nuc; PI-PLC; PPIase; PpiB; PrsA; Staphylococcus aureus; cyclophilin; nuclease; parvulin; protease