Defense against own arms: staphylococcal cysteine proteases and their inhibitors

Area of Science:

• Microbiology
• Biochemistry
• Pathogenesis

Background:

• Staphylococcus aureus is a significant human pathogen responsible for diverse diseases.
• Staphylococcal infections often lack toxigenicity, with limited understanding of their pathogenesis.
• Secreted proteins are hypothesized to mediate colonization and infection, including several proteases.

Purpose of the Study:

• To review current knowledge on staphylococcal cysteine proteases and their inhibitors.
• To elucidate the network of these enzymes and their regulators.
• To assess their potential roles as virulence factors in Staphylococcus aureus infections.

Main Methods:

• Literature review of existing studies on staphylococcal proteases and inhibitors.
• Analysis of the proposed functions of cysteine proteases (staphopain A [ScpA] and staphopain B [SspB]).
• Examination of newly described cysteine protease inhibitors (staphostatin A [ScpB] and staphostatin B [SspC]).

Main Results:

• Two key cysteine proteases, ScpA and SspB, are identified in S. aureus.
• Two corresponding inhibitors, ScpB and SspC, have been recently characterized.
• The interplay between these proteases and inhibitors suggests a complex regulatory network.

Conclusions:

• The staphylococcal cysteine protease and inhibitor network is intricate.
• These enzymes and their regulators are implicated as potential virulence factors in S. aureus.
• Further in vivo data is needed to fully understand their contribution to infection.