A distinctive family of L,D-transpeptidases catalyzing L-Ala-mDAP crosslinks in Alpha- and Betaproteobacteria.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38351082.
- Also identified by DOI 10.1038/s41467-024-45620-5 and PMC identifier 10864386.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The bacterial cell-wall peptidoglycan is made of glycan strands crosslinked by short peptide stems. Crosslinks are catalyzed by DD-transpeptidases (4,3-crosslinks) and LD-transpeptidases (3,3-crosslinks). However, recent research on non-model species has revealed novel crosslink types, suggesting the existence of uncharacterized enzymes. Here, we identify an LD-transpeptidase, LDT<sub>Go</sub>, that generates 1,3-crosslinks in the acetic-acid bacterium Gluconobacter oxydans. LDT<sub>Go</sub>-like proteins are found in Alpha- and Betaproteobacteria lacking LD3,3-transpeptidases. In contrast with the strict specificity of typical LD- and DD-transpeptidases, LDT<sub>Go</sub> can use non-terminal amino acid moieties for crosslinking. A high-resolution crystal structure of LDT<sub>Go</sub> reveals unique features when compared to LD3,3-transpeptidases, including a proline-rich region that appears to limit substrate access, and a cavity accommodating both glycan chain and peptide stem from donor muropeptides. Finally, we show that DD-crosslink turnover is involved in supplying the necessary substrate for LD1,3-transpeptidation. This phenomenon underscores the interplay between distinct crosslinking mechanisms in maintaining cell wall integrity in G. oxydans.
Medical subject headings
- Peptidyl Transferases