Molecular Mechanisms Influencing Bacterial Conjugation in the Intestinal Microbiota

Abstract

Bacterial conjugation is a widespread and particularly efficient strategy to horizontally disseminate genes in microbial populations. With a rich and dense population of microorganisms, the intestinal microbiota is often considered a fertile environment for conjugative transfer and a major reservoir of antibiotic resistance genes. In this mini-review, we summarize recent findings suggesting that few conjugative plasmid families present in Enterobacteriaceae transfer at high rates in the gut microbiota. We discuss the importance of mating pair stabilization as well as additional factors influencing DNA transfer efficiency and conjugative host range in this environment. Finally, we examine the potential repurposing of bacterial conjugation for microbiome editing.

Keywords: antibiotic resistance; bacterial conjugation; conjugative plasmids (CP); mating pair stabilization; microbiota.

FIGURE 1

Factors influencing bacterial conjugation. (A) Bacterial conjugation taking place on solid support provides high cell density and close proximity between donor and recipient cells that facilitate mating-pair formation to enable plasmid transfer. (B) Bacteria evolving in liquid environments or (C) in vivo benefit from mating-pair stabilization (MPS) provided either by F-pili or type IVb pili to bring cells together and keep them in close contact during plasmid transfer. (D) Venn diagram showing the factors contributing to the effective host range of a mobile genetic element. (E) Schematic representation of R64’s shufflon where the C-terminus region of the pilV gene can undergo DNA rearrangement catalyzed by the shufflase (rci) to allow expression of seven variants of PilV. For example, DNA region A could be exchanged to express A′. (F) DNA rearrangement of the shufflon in the donor strain determines recipient specificity when mating occurred in broth/in vivo conditions. Created in BioRender.com.