Staphylococcus aureus Trigger Factor Is Involved in Biofilm Formation and Cooperates with the Chaperone PpiB

Abstract

Peptidyl-prolyl cis/trans isomerases (PPIases) are enzymes that assist in protein folding around proline-peptide bonds, and often possess chaperone activity. Staphylococcus aureus encodes three PPIases; PrsA, PpiB and Trigger factor (TF). Previous work by our group demonstrated a role for both PrsA and PpiB in S. aureus, however, TF remains largely unstudied. Here, we identify a role for TF in S. aureus biofilm formation, and demonstrate cooperation between TF and the cytoplasmic PPIase PpiB. Mutation of the tig gene (encoding TF) leads to reduced biofilm development in vitro but no significant attenuation of virulence in a mouse model of infection. To investigate if TF possesses chaperone activity, we analyzed the ability of a tig mutant to survive acid and basic stress. While there was no significant decrease in a tig mutant, a ppiB/tig double mutant exhibited a significant decrease in cell viability after acid and base challenge. We then demonstrate that a ppiB/tig double mutant has exacerbated phenotypes in vitro and in vivo when compared to either single mutant. Finally, in vivo immunoprecipitation of epitope tagged PpiB reveals that PpiB interacts with four times the number of proteins when TF is absent from the cell, suggesting it may be compensating for the loss of TF. Interestingly, the only proteins found to interact with TF are TF itself, FnBPB and the chaperone protein ClpB. Collectively, these results support the first phenotype for S. aureus TF and demonstrate a greater network of cooperation between chaperone proteins in Staphylococcus aureus. IMPORTANCE S. aureus encodes a large number of virulence factors that aid the bacterium in survival and pathogenesis. These virulence factors have a wide variety of functions, however, they must all be properly secreted in order to be functional. Bacterial chaperone proteins often assist in secretion by trafficking proteins to secretion machinery or assisting in proper protein folding. Here, we report that the S. aureus chaperone Trigger factor (TF) contributes to biofilm formation and cooperates with the chaperone PpiB to regulate S. aureus virulence processes. These data highlight the first known role for TF in S. aureus, and suggest that S. aureus chaperone proteins may be involved in a greater regulatory network in the cell.

Proteomic Investigation over the Antimicrobial Photodynamic Therapy Mediated by Rose Bengal Against Staphylococcus aureus

“…5), in which Tig behaves as a centroid with edges pointing to chaperones: foldase protein, putative peptidyl-prolyl cis-trans isomerase and ATP-dependent Clp protease proteolytic subunit. We reproduced the same compensation pattern described by Keogh et al (54), with the upregulation of Tig being reflective of the downregulation of PrsA, PPIase and ClpP, which play roles in the correct protein folding. Energy metabolism perturbations are also a consequence of the oxidative stress imposed by drugs (55).…”

“…We suggest those alterations as a stress response against the potential disseminated ROS damage in protein structures triggered by the photoactivation by RB. According to Keogh et al (54), S. aureus could upregulate Tig expression under stress to compensate for the loss of or decrease in proteins with chaperone activity. This was observed in the protein network (Fig.…”

“…According to Keogh et al . (54), S. aureus could upregulate Tig expression under stress to compensate for the loss of or decrease in proteins with chaperone activity. This was observed in the protein network (Fig.…”

“…We reproduced the same compensation pattern described by Keogh et al . (54), with the upregulation of Tig being reflective of the downregulation of PrsA, PPIase and ClpP, which play roles in the correct protein folding.…”

Molecular co-localization of multiple drugs in a nanoscopic delivery vehicle for potential synergistic remediation of multi-drug resistant bacteria

“…In MRSA, clpX is an essential element which governs virulence 92 tig, SACOL1722 Indirect trigger factor involves in protein export in a mouse model of infection. tig gene mutation led to reduced biofilm development but no substantial decrease in virulence 93 diethylene glycol Indirect Poly(ethylene glycol) coatings are familiar for reduction in microbial adhesion by numbers and binding strength 94 guanosine diphosphate guanosine triphosphate Indirect They help bacteria to adjust according to different environmental stresses 95 Magnesium Indirect Mg2+ metal ions rupture S. aureus membranes and kill stationary-phase S. aureus cells, which denotes membrane-activity 96 SeMet Indirect SeMet may inhibit bacterial growth and is protective on macrophages 97 …”