Pull in and Push Out: Mechanisms of Horizontal Gene Transfer in Bacteria

Abstract

Horizontal gene transfer (HGT) plays an important role in bacterial evolution. It is well accepted that DNA is pulled/pushed into recipient cells by conserved membrane-associated DNA transport systems, which allow the entry of only single-stranded DNA (ssDNA). However, recent studies have uncovered a new type of natural bacterial transformation in which double-stranded DNA (dsDNA) is taken up into the cytoplasm, thus complementing the existing methods of DNA transfer among bacteria. Regulated by the stationary-phase regulators RpoS and cAMP receptor protein (CRP), Escherichia coli establishes competence for natural transformation with dsDNA, which occurs in agar plates. To pass across the outer membrane, a putative channel, which may compete for the substrate with the porin OmpA, may mediate the transfer of exogenous dsDNA into the cell. To pass across the inner membrane, dsDNA may be bound to the periplasmic protein YdcS, which delivers it into the inner membrane channel formed by YdcV. The discovery of cell-to-cell contact-dependent plasmid transformation implies the presence of additional mechanism(s) of transformation. This review will summarize the current knowledge about mechanisms of HGT with an emphasis on recent progresses regarding non-canonical mechanisms of natural transformation. Fully understanding the mechanisms of HGT will provide a foundation for monitoring and controlling multidrug resistance.

The manifold roles of microbial ribosomal peptide–based natural products in physiology and ecology

“…In this sense, deciphering more deeply the fine-tuning regulations managing RiPP production, their effects at low doses, their pheromone function, and their roles in QS and biofilm formation as well as in interbacterial predation is expected to expand our knowledge of their native function. Furthermore, as mentioned above, elucidating the tight JBC REVIEWS: Microbial ribosomal peptide natural products relationships between the aforementioned functions and DNA acquisition by naturally competent bacteria (234,235) will afford rich perspectives. Indeed, natural transformation is a driving force for adaptation and evolution through horizontal gene transfer (236), and involvement of bacteriocins in the process has already been suggested (171,237), prefiguring a putative role that could be played by RiPPs in these processes.…”

Harvesting of Prebiotic Fructooligosaccharides by Nonbeneficial Human Gut Bacteria

“…This result indicates that the structure of the Dorea FOS locus has been altered during its evolution, which might be due to (i) the a posteriori gene acquisition of the Dorea pts gene from an existing locus or (ii) its loss within some bacterial populations over time. Both events could have been driven by horizontal gene transfer, an essential phenomenon for bacterial genome plasticity and metabolic adaptability (47). Nevertheless, when comparing gene abundance and prevalence in the microbiome of individuals of various origins and medical statuses, the pts gene presents the same relative profile as the other genes of the FOS utilization locus.…”

Bartonellagene transfer agent: Evolution, function, and proposed role in host adaptation

“…Gene transfer agents (GTAs) are commonly defined as virus‐like particles that mediate DNA transfer from the organism that encodes them into competent recipient cells (recently reviewed in Grull, Mulligan, & Lang, ; Lang, Westbye, & Beatty, ). As such, they constitute an important mechanism underlying HGT in addition to conjugation, natural competence, and bacteriophage‐mediated transduction (Sun, ; von Wintersdorff et al, ). It is generally accepted that GTAs originate from defective temperate prophages, in a process that has been conceptualised as “prophage domestication” (Bobay, Touchon, & Rocha, ; Harrison & Brockhurst, ; Olszak, Latka, Roszniowski, Valvano, & Drulis‐Kawa, ).…”