Natural Transformation of Myxococcus xanthus

Abstract

Myxococcus xanthus belongs to the delta class of the proteobacteria and is notable for its complex life-style with social behaviors and relatively large genome. Although previous observations have suggested the existence of horizontal gene transfer in M. xanthus, its ability to take up exogenous DNA via natural transformation has not been experimentally demonstrated. In this study, we achieved natural transformation in M. xanthus using the autonomously replicating myxobacterial plasmid pZJY41 as donor DNA. M. xanthus exopolysaccharide (EPS) was shown to be an extracellular barrier for transformation. Cells deficient in EPS production, e.g., mutant strains carrying ⌬difA or ⌬epsA, became naturally transformable. Among the inner barriers to transformation were restriction-modification systems in M. xanthus, which could be partially overcome by methylating DNA in vitro using cell extracts of M. xanthus prior to transformation. In addition, the incubation time of DNA with cells and the presence of divalent magnesium ion affected transformation frequency of M. xanthus. Furthermore, we also observed a potential involvement of the type IV pilus system in the DNA uptake machinery of M. xanthus. The natural transformation was totally eliminated in the ⌬pilQ/epsA and ⌬tgl/epsA mutants, and null mutation of pilB or pilC in an ⌬epsA background diminished the transformation rate. Our study, to the best of our knowledge, provides the first example of a naturally transformable species among deltaproteobacteria.

Allopatric integrations selectively change host transcriptomes, leading to varied expression efficiencies of exotic genes in Myxococcus xanthus

“…A further transformation performance of p15A-Tp-CF in M. xanthus DK1622 strain yielded 30 correct transformants from 59 antibiotics-resistant colonies. We also performed transformations in SW504, a difA mutant of M. xanthus DK1622 [ 22 , 23 ], from which 4 correct transformants were obtained. Figure 2 c demonstrates some PCR amplification results.…”

A barrier to homologous recombination between sympatric strains of the cooperative soil bacterium Myxococcus xanthus

“…Our population-genomic approach did not allow us to distinguish between the latter two hypotheses, especially as the mechanisms by which recombination in M. xanthus occurs are largely unknown. Natural transformation has been achieved under artificial conditions ( Wang et al , 2011 ) and M. xanthus- specific transducing phages have been isolated ( Martin et al , 1978 ) but no conjugation-mediated recombination has been found. However, it is unclear what mechanisms primarily drive recombination in nature.…”

DNA Builds and Strengthens the Extracellular Matrix in Myxococcus xanthus Biofilms by Interacting with Exopolysaccharides

“…6A), suggesting that the presence of eDNA and its interaction with EPS is highly relevant to strength of biofilm ECM and survival under adverse environments. In addition, EPS has been shown to be an extracellular barrier and able to block the plasmid transformation in M. xanthus [50]. This may occur through the EPS interaction with eDNA which would lower DNA local effective concentration, thus allowing only cells deficient in EPS production to be naturally transformable.…”