pbp2229-Mediated Nisin Resistance Mechanism in Listeria monocytogenes Confers Cross-Protection to Class IIa Bacteriocins and Affects Virulence Gene Expression

Date
2004
Authors
Gravesen A.
Kallipolitis B.
Holmstrom K.
Hoiby P.E.
Ramnath M.
Knochel S.
Journal Title
Journal ISSN
Volume Title
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Abstract
It was previously shown that enhanced nisin resistance in some mutants was associated with increased expression of three genes, pbp2229, hpk1021, and Imo2487, encoding a penicillin-binding protein, a histidine kinase, and a protein of unknown function, respectively. In the present work, we determined the direct role of the three genes in nisin resistance. Interruption of pbp2229 and hpk1021 eliminated the nisin resistance phenotype. Interruption of hpk1021 additionally abolished the increase in pbp2229 expression. The results indicate that this nisin resistance mechanism is caused directly by the increase in pbp2229 expression, which in turn is brought about by the increase in hpk1021 expression. We also found a degree of cross-protection between nisin and class Ila bacteriocins and investigated possible mechanisms. The expression of virulence genes in one nisin-resistant mutant and two class IIa bacteriocin-resistant mutants of the same wild-type strain was analyzed, and each mutant consistently showed either an increase or a decrease in the expression of virulence genes (prfA-regulated as well as prfA-independent genes). Although the changes mostly were moderate, the consistency indicates that a mutant-specific change in virulence may occur concomitantly with bacteriocin resistance development.
Description
Keywords
Cytology, Drug products, Enzymes, Genes, Microbiology, Bacteriocins, Gene expressions, Bacteria, bacteriocin, bacteriocin 2a, histidine kinase homologue 1021, nisin, penicillin binding protein, penicillin binding protein 2229, protein, protein histidine kinase, protein lmo1021, unclassified drug, bacterium, article, bacterial gene, bacterial virulence, gene expression, Listeria monocytogenes, phenotype, protein expression, Bacteriocins, Base Sequence, DNA, Bacterial, Drug Resistance, Bacterial, Gene Expression, Genes, Bacterial, Listeria monocytogenes, Mutagenesis, Insertional, Mutation, Nisin, Oligonucleotide Array Sequence Analysis, Phenotype, Virulence, Animalia, Bacteria (microorganisms), Listeria monocytogenes, Posibacteria, Prokaryota
Citation
Applied and Environmental Microbiology
70
3