Staphylococcal SplA and SplB Serine Protease Allelic Variants Exhibit Different Substrate Specificities
Felix L Glinka1, Katharina Mehnert1, Lena Koch1
1Dept. of Biotechnology & Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, 17489, Greifswald, Germany.
Chembiochem : a European Journal of Chemical Biology
|December 22, 2025
Summary
Staphylococcus aureus virulence factors, like SplA and SplB, exhibit significant allelic variation. This diversity impacts their function and substrate specificity, crucial for understanding bacterial infection.
Area of Science:
- Microbiology
- Biochemistry
- Pathogen Evolution
Background:
- Staphylococcus aureus is a common human colonizer and opportunistic pathogen.
- Extracellular serine protease-like proteins (Spls) are secreted virulence factors of S. aureus.
- The role and variation of Spls in infection are poorly understood.
Purpose of the Study:
- To biochemically characterize allelic variants of S. aureus SplA and SplB.
- To investigate how allelic variation affects Spl protein function and substrate specificity.
- To understand the evolutionary significance of virulence factor diversity in S. aureus.
Main Methods:
- Biochemical characterization of selected SplA and SplB allelic variants.
- Enzymatic activity and stability assays.
- Substrate specificity analysis using known Spl targets (RickULP, SseL).
Main Results:
- Allelic variants of SplA and SplB display distinct stability and enzymatic activity.
- Different Spl variants exhibit altered substrate specificity and cleavage patterns for RickULP and SseL.
- One SplB variant showed substrate selectivity similar to SplE, differing from wildtype SplB.
Conclusions:
- Allelic variation in S. aureus Spl proteins significantly impacts their biochemical properties and substrate interactions.
- Understanding Spl variant diversity is essential for comprehending S. aureus pathogenesis and host-pathogen dynamics.
- This study provides insights into the evolution of bacterial virulence factors through allelic diversification.
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