Absence of a putative mannose-specific phosphotransferase system enzyme IIAB component in a leucocin A-resistant strain of Listeria monocytogenes, as shown by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Leucocin A is a class IIa bacteriocin produced by Leuconostoc spp. that has previously been shown to inhibit the growth of Listeria monocytogenes. A spontaneous resistant mutant of L. monocytogenes was isolated and found to be resistant to leucocin A at levels in excess of 2 mg/ml. The mutant showed no significant cross-resistance to nontype IIa bacteriocins including nisaplin and ESF1-7GR. However, there were no inhibition zones found on a lawn of the mutant when challenged with an extract containing 51,200 AU of pediocin PA-2 per ml as determined by a simultaneous assay on the sensitive wild-type strain. DNA and protein analysis of the resistant and susceptible strains were carried out using silver-stained amplified fragment length polymorphism (ssAFLP) and one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. Two-dimensional SDS-PAGE clearly showed a 35-kDa protein which was present in the sensitive but absent from the resistant strain. The N-terminal end of the 35-kDa protein was sequenced and found to have an 83% homology to the mannose-specific phosphotransferase system enzyme IIAB of Streptococcus salivarius.
Ramnath
M
M
School of Molecular and Cellular Biosciences, University of Natal, Scottsville, Pietermaritzburg, South Africa.
Beukes
M
M
Tamura
K
K
Hastings
J W
JW
D001430:Bacteriocins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D015180:Electrophoresis, Gel, Two-Dimensional; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D008358:Mannose / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D012150:Polymorphism, Restriction Fragment Length
D001430:Bacteriocins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C037992:phosphoenolpyruvate-mannose phosphotransferase; D008358:Mannose