ArdA proteins from different mobile genetic elements can bind to the EcoKI Type I DNA methyltransferase of E. coli K12

Abstract

Anti-restriction and anti-modification (anti-RM) is the ability to prevent cleavage by DNA restriction–modification (RM) systems of foreign DNA entering a new bacterial host. The evolutionary consequence of anti-RM is the enhanced dissemination of mobile genetic elements. Homologues of ArdA anti-RM proteins are encoded by genes present in many mobile genetic elements such as conjugative plasmids and transposons within bacterial genomes. The ArdA proteins cause anti-RM by mimicking the DNA structure bound by Type I RM enzymes. We have investigated ArdA proteins from the genomes of Enterococcus faecalis V583, Staphylococcus aureus Mu50 and Bacteroides fragilis NCTC 9343, and compared them to the ArdA protein expressed by the conjugative transposon Tn916. We find that despite having very different structural stability and secondary structure content, they can all bind to the EcoKI methyltransferase, a core component of the EcoKI Type I RM system. This finding indicates that the less structured ArdA proteins become fully folded upon binding. The ability of ArdA from diverse mobile elements to inhibit Type I RM systems from other bacteria suggests that they are an advantage for transfer not only between closely-related bacteria but also between more distantly related bacterial species.

Genome-wide correlation analysis suggests different roles of CRISPR-Cas systems in the acquisition of antibiotic resistance genes in diverse species

“…While anti-CRISPRs may reduce CRISPR-Cas defence against phages, this may enable the benefits of acquisition of ARGs. Previous studies on other MGE counter defence proteins, such as anti-restriction proteins, or ArdA from conjugative plasmids and transposons, also demonstrated a similar inhibition of the dissemination of antibiotic resistance in different species [73,74]. In P. aeruginosa, we observed a significant influence of anti-CRISPRs on the prevalence of antibiotic resistance (figure 4).…”

High genomic variability in the plant pathogenic bacterium Pectobacterium parmentieri deciphered from de novo assembled complete genomes

“…The here described pPAR01 plasmid retains other exciting features, which could be related to its possible transmissibility. For instance, anti-restriction proteins ArdA and KlcA, which may allow for the associated MGE to evade the ubiquitous Type I DNA restriction systems in the recipient bacterium [ 62 ] resulting in the acquisition of cognate modification. Also, the presence of the gene coding for N6 DNA methylase suggests that maintaining this plasmid may affect histone methylation pattern within the host DNA to avoid further invasion by foreign nucleic acids [ 63 ].…”

Comparison between complete genomes of an isolate of Pseudomonas syringae pv. actinidiae from Japan and a New Zealand isolate of the pandemic lineage

“…The Pac_ICEs and plasmids may be able to evade restriction, in part because they are transferred as single stranded molecules. In addition, horizontally transferred mobile elements such as ICE or plasmids may avoid restriction through the presence of anti-restriction proteins 37 , 38 . In numerous cases of the acquisition of the R-M systems, it is possible to determine a potential probable source of the horizontal transfer.…”