Work

Structural basis for TrbM-enhanced conjugation and interbacterial killing in the RP4 plasmid

Year: 2026

Type: article

Abstract: Bacterial conjugation drives horizontal gene transfer and antibiotic resistance via type IV secretion systems (T4SS) on conjugative plasmids like RP4. Previously, we found that the RP4-T4SS mediates interbacterial killing, a process enhanced by the uncharacterized gene trbM . Here, we characterize RP4-TrbM and identify structural features essential for boosting both conjugation and killing. Computational analyses reveal that the RP4-TrbM shares similarities with known bacterial adhesins in other conjugative systems. Homologs from plasmids R751, R388, and pKM101 could complement RP4-TrbM-knockout strains, restoring and enhancing conjugation (R751-TrbM and pKM101-Pep) and conjugation-associated killing (R751-TrbM, R388-KikA, and pKM101-Pep), while TivB12 from conjugative plasmid R6K could not complement the RP4-T4SS. Furthermore, we identified an essential functional domain in RP4-TrbM that retains activity even when repositioned between a different signal peptide and C terminus. These findings expand our understanding of the RP4 conjugative machinery and highlight TrbM-like proteins as promising targets for inhibiting T4SS-mediated processes.

Source: iScience

DOI: 10.1016/j.isci.2026.116436

Authors: Lois Gordils-Valentin, Jackson Belobrajdic, Xuejun Zhu

Institution: Texas A&M University

Language: English

Topic: Bacterial Genetics and Biotechnology

Subfield: Genetics

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: gold

Estimated APC paid: $3,240

Funders: Texas A and M University, National Institutes of Health, Artie McFerrin Department of Chemical Engineering, Texas A and M University, National Institute of General Medical Sciences