Anti-Restriction Protein, KlcAHS, Promotes Dissemination of Carbapenem Resistance

Abstract

Carbapenemase-producing Klebsiella pneumoniae (KPC) has emerged and spread throughout the world. A retrospective analysis was performed on carbapenem-resistant K. pneumoniae isolated at our teaching hospital during the period 2009–2010, when the initial outbreak occurred. To determine the mechanism(s) that underlies the increased infectivity exhibited by KPC, Multilocus Sequence Typing (MLST) was conducted. A series of plasmids was also extracted, sequenced and analyzed. Concurrently, the complete sequences of blaKPC−2-harboring plasmids deposited in GenBank were summarized and aligned. The blaKPC−2 and KlcAHS genes in the carbapenem-resistant K. pneumoniae isolates were examined. E. coli strains, carrying different Type I Restriction and Modification (RM) systems, were selected to study the interaction between RM systems, anti-RM systems and horizontal gene transfer (HGT). The ST11 clone predominated among 102 carbapenem-resistant K. pneumoniae isolates, all harbored the blaKPC−2 gene; 98% contained the KlcAHS gene. KlcAHS was one of the core genes in the backbone region of most blaKPC−2 carrying plasmids. Type I RM systems in the host bacteria reduced the rate of pHS10842 plasmid transformation by 30- to 40-fold. Presence of the anti-restriction protein, KlcAHS, on the other hand, increased transformation efficiency by 3- to 6-fold. These results indicate that RM systems can significantly restrict HGT. In contrast, KlcAHS can disrupt the RM systems and promote HGT by transformation. These findings suggest that the anti-restriction protein, KlcAHS, represents a novel mechanism that facilitates the increased transfer of blaKPC-2 and KlcAHS-carrying plasmids among K. pneumoniae strains.

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.…”

Emergence and establishment of KPC-2-producing ST11 Klebsiella pneumoniae in a general hospital in Shanghai, China

“…The transmission of bla KPC-2 can be mediated by different molecular mechanisms, but the factors contributing to the epidemiological success of KPC-producing K. pneumoniae clonal complex (CC) 258 is unclear [ 13 ]. Recently, Liang et al [ 14 ] found that the KPC-2-producing ST11 K. pneumoniae can code an anti-restriction protein KlcA HS , which may help prevent the host bacteria from recognizing and incising foreign DNA by disrupting the restriction modification (RM) systems. The strains in this study also have bla KPC-2 and KlcA HS simultaneously (data not shown).…”

Genomic epidemiology of a complex, multi-species plasmid-borne blaKPC carbapenemase outbreak in Enterobacterales in the UK, 2009-2014

“…In addition to their plasticity, part of the success of these bla KPC plasmids may also be attributable to the presence of toxin-antitoxin plasmid addiction systems ( ccdA / ccdB n=4 bla KPC plasmids; higA n=6; vapB/vapC n=11); anti-restriction mechanisms ( klcA n=16, previously shown to promote bla KPC dissemination(22)); and heavy metal resistance ( terB [tellurite] n=3; ars operon [arsenicals] n=3; chromate resistance n=1; cop operon/ pcoC / pcoE [copper] n=7; mer operon [mercury] n=10).…”