Structural implication of substrate binding by peptidoglycan remodeling enzyme MepS.

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Bacterial cell growth and morphogenesis rely on constant peptidoglycan (PG) remodeling.
• Murein DD-endopeptidase (MepS) is a key enzyme that cleaves PG, essential for cell viability.
• MepS activity is tightly regulated, making it a potential antibiotic target.

Purpose of the Study:

• To elucidate the structural basis of MepS substrate recognition and degradation.
• To understand how MepS interacts with peptidoglycan.
• To provide insights for designing novel MepS-targeting antibiotics.

Main Methods:

• High-resolution structural determination of MepS (MepS-C68S mutant).
• Biochemical analysis of MepS-C68S interactions with organic acids and peptide models.
• Molecular modeling of MepS bound to a peptidoglycan peptide.

Main Results:

• Citrate and L-malate were observed to bind to the MepS-C68S active site.
• Conserved surface residues indicated potential peptide binding sites.
• A model showed a cross-linked peptidoglycan peptide (meso-DAP-D-Ala-meso-DAP) bound to MepS-C68S.
• Tyrosine residues Tyr56 and Tyr147 were identified as crucial for peptide recognition.

Conclusions:

• Structural insights into MepS function and substrate binding have been obtained.
• The study highlights MepS as a promising target for novel antibiotic development.
• Understanding MepS-PG interactions can guide the design of specific inhibitors.