A Klebsiella pneumoniae DedA family membrane protein is required for colistin resistance and for virulence in wax moth larvae

Abstract

Ineffectiveness of carbapenems against multidrug resistant pathogens led to the increased use of colistin (polymyxin E) as a last resort antibiotic. A gene belonging to the DedA family encoding conserved membrane proteins was previously identified by screening a transposon library of K. pneumoniae ST258 for sensitivity to colistin. We have renamed this gene dkcA (dedA of Klebsiella required for colistin resistance). DedA family proteins are likely membrane transporters required for viability of Escherichia coli and Burkholderia spp. at alkaline pH and for resistance to colistin in a number of bacterial species. Colistin resistance is often conferred via modification of the lipid A component of bacterial lipopolysaccharide with aminoarabinose (Ara4N) and/or phosphoethanolamine. Mass spectrometry analysis of lipid A of the ∆dkcA mutant shows a near absence of Ara4N in the lipid A, suggesting a requirement for DkcA for lipid A modification with Ara4N. Mutation of K. pneumoniae dkcA resulted in a reduction of the colistin minimal inhibitory concentration to approximately what is found with a ΔarnT strain. We also identify a requirement of DkcA for colistin resistance that is independent of lipid A modification, instead requiring maintenance of optimal membrane potential. K. pneumoniae ΔdkcA displays reduced virulence in Galleria mellonella suggesting colistin sensitivity can cause loss of virulence.

Exploring Cluster-Dependent Antibacterial Activities and Resistance Pathways of NOSO-502 and Colistin against Enterobacter cloacae Complex Species

“…These results seem different from those observed in K. pneumoniae by Cheng et al who demonstrated that CrrC, an ortholog gene of ECL_01760, regulated the pmrHFIJKLM operon, also called arnBCADTEF , and pmrC through the PmrAB TCS ( 25 ). Interestingly, in K. pneumoniae , the small protein DkcA, displays similarity to membrane transporter and is required for CST resistance in a lipid A-dependent and-independent manner ( 39 ). DkcA is required for lipid A modification with Ara4N by a yet unidentified mechanism, but authors hypothesized that it would play a role in the arn pathway or by maintaining an inner membrane potential necessary for the CST antibacterial activity.…”

Identification of potential novel membrane drug targets of Acinetobacter baumannii ATCC 19606 using subtractive proteomics approach

“…The DedA family proteins are highly conserved membrane proteins, but they are poorly characterized and their functions still remain unknown. However, there are some hypotheses that the DedA family proteins can function as the proton-dependent transporters, provide colistin resistance and take part in the normal cell division [23,24].…”

Three bacterial DedA subfamilies with distinct functions and phylogenetic distribution

“…It is found in all major bacterial clades except for the peptidoglycan-less Tenericutes and the Thermotogota (Table 1). Almost all experimentally studied bacterial DedAs are in this family, including the sole (and essential) DedA of Borrelia burgdoferi (11), the target of the antibiotic halicyclamine A in Mycobacterium smegmatis (12), as well as DedAs implicated in colistin resistance through 4-amino-4-deoxy-Larabinose modification of Lipid A in Klebsiella pneumoniae (13), Enterobacter cloacae (14), Burkholderia thailandensis (15), and Burkholderia glumae (16), and others (17)(18)(19).…”