The penicillin resistance of Enterococcus faecalis JH2-2r results from an overproduction of the low-affinity penicillin-binding protein PBP4 and does not involve a psr-like gene

• Published in: Microbiology (Society for General Microbiology) Vol. 147; no. 9; pp. 2561 - 2569
• Main Authors: Duez, Colette, Zorzi, Willy, Sapunaric, Frederic, Amoroso, Ana, Thamm, Iris, Coyette, Jacques
• Format: Journal Article Web Resource
• Language: English
• Published: Reading Soc General Microbiol 01-09-2001; Society for General Microbiology
• Subjects: Bacterial Proteins; Bacteriology; Base Sequence; Biological and medical sciences; Carrier Proteins - biosynthesis; Carrier Proteins - genetics; Cloning, Molecular; DNA, Bacterial - genetics; Enterococcus faecalis; Enterococcus faecalis - drug effects; Enterococcus faecalis - genetics; Enterococcus faecalis - metabolism; Enterococcus faecalis - pathogenicity; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; Genes, Bacterial; Genetics; Hexosyltransferases; Humans; Life sciences; Microbiologie; Microbiology; Molecular Sequence Data; Muramoylpentapeptide Carboxypeptidase - biosynthesis; Muramoylpentapeptide Carboxypeptidase - genetics; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; PBP4 protein; Penicillin Resistance - genetics; Penicillin Resistance - physiology; Penicillin-Binding Proteins; Peptidyl Transferases; Plasmids - genetics; pénicilline; résistance; Sciences du vivant; Enterococcus faecalis; Binding; β-Lactams; Benzylpenicillin; Concentration; Plate; Penicillin binding protein; Result; Penicillin derivatives; Resistance; Streptococcaceae; Binding protein; Gene; Bacteria; Micrococcales; Affinity; Isolate; Isolation; Mutation
• ISSN: 1350-0872; 1465-2080; 1465-2080
• DOI: 10.1099/00221287-147-9-2561

Centre d’Ingénierie des Protéines, Institut de Chimie, B6, Université de Liège, (Sart Tilman), B-4000 Liège, Belgium 1
Author for correspondence: Jacques Coyette. Tel: [phone]. Fax: [phone]. e-mail: jcoyette{at}ulg.ac.be
A penicillin-resistant mutant, JH2-2r (MIC 75 µg ml -1 ), was isolated from Enterococcus faecalis JH2-2 (MIC 5 µg ml -1 ) by successive passages on plates containing increasing concentrations of benzylpenicillin. A comparison of the penicillin-binding protein (PBP) profiles in the two strains revealed a more intensely labelled PBP4 in JH2-2r. Because the sequences of the JH2-2 and JH2-2r pbp4 genes were strictly identical, even in their promoter regions, this intensive labelling could only be associated with an overproduction of the low-affinity PBP4. No psr gene analogous to that proposed to act as a regulator of PBP5 synthesis in Enterococcus hirae and Enterococcus faecium could be identified in the vicinity of pbp4 in E. faecalis JH2-2 and JH2-2r. However, a psr -like gene distant from pbp4 was identified. The cloning and sequencing of that psr -like gene from both E. faecalis strains indicated that they were identical. It is therefore postulated that the PBP4 overproduction in E. faecalis JH2-2r results from the modification of an as yet unidentified factor.
Keywords: ß-lactam resistance, low-affinity PBP, PBP-synthesis repressor ( psr ) gene Abbreviations: HMM, high molecular mass; LMM, low molecular mass; PBP, penicillin-binding protein
The GenBank accession numbers for the sequences reported in this paper are Y17797 for the 8·4 kb segment of pDML521; AJ290435 for pbp4 of E. faecalis JH2-2; AJ276231 and AJ276232 for the psr -like gene of E. faecalis JH2-2 or JH2-2r, respectively.
a Present address: Laboratory of Human Histology, Institut A. Swaen, L3, Université de Liège, rue des Pitteurs 20, B-4020 Liège, Belgium.
b Present address: Departamento de Microbiologia y Immunologia, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Junin 956, 1113 Buenos Aires, Argentina.