eLife Assessment: Fine-tuning of outer membrane–peptidoglycan tethering by the redox-active lipoprotein LppB from Salmonella enterica

This important study convincingly demonstrates how bacterial cells can modulate outer membrane-peptidoglycan tethering by expressing two different Lpp homologs with distinct cross-linking efficiencies, revealing that Salmonella typhimurium LppB forms disulfide-based homodimers (or heterotrimers with Lpp when present) and is covalently attached to peptidoglycan primarily via the L,D-transpeptidase LdtB at residue K58.The evidence supporting the authors' claims is solid, including the regulatory role of LppB dimerization for its abundance in E. coli and its ability to inhibit Lpp/A crosslinking to peptidoglycan, although additional analysis and quantification of muropeptides in wildtype E. coli overexpressing LppB would further strengthen the findings.Overall, the work will be of great interest to microbiologists studying cell envelope biogenesis.