HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 279, Issue 39, 40802-40806, September 24, 2004

This Article Full Text Full Text (PDF) All Versions of this Article: 279/39/40802    most recent M403589200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fuda, C. Articles by Mobashery, S. Search for Related Content PubMed PubMed Citation Articles by Fuda, C. Articles by Mobashery, S. Social Bookmarking                      What's this?

The Basis for Resistance to -Lactam Antibiotics by Penicillin-binding Protein 2a of Methicillin-resistant Staphylococcus aureus^*

Cosimo Fuda, Maxim Suvorov, Sergei B. Vakulenko, and Shahriar Mobashery

From the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556

Penicillin-binding protein 2a (PBP2a) of Staphylococcus aureus is refractory to inhibition by available -lactam antibiotics, resulting in resistance to these antibiotics. The strains of S. aureus that have acquired the mecA gene for PBP2a are designated as methicillin-resistant S. aureus (MRSA). The mecA gene was cloned and expressed in Escherichia coli, and PBP2a was purified to homogeneity. The kinetic parameters for interactions of several -lactam antibiotics (penicillins, cephalosporins, and a carbapenem) and PBP2a were evaluated. The enzyme manifests resistance to covalent modification by -lactam antibiotics at the active site serine residue in two ways. First, the microscopic rate constant for acylation (k₂) is attenuated by 3 to 4 orders of magnitude over the corresponding determinations for penicillin-sensitive penicillin-binding proteins. Second, the enzyme shows elevated dissociation constants (K_d) for the non-covalent pre-acylation complexes with the antibiotics, the formation of which ultimately would lead to enzyme acylation. The two factors working in concert effectively prevent enzyme acylation by the antibiotics in vivo, giving rise to drug resistance. Given the opportunity to form the acyl enzyme species in in vitro experiments, circular dichroism measurements revealed that the enzyme undergoes substantial conformational changes in the course of the process that would lead to enzyme acylation. The observed conformational changes are likely to be a hallmark for how this enzyme carries out its catalytic function in cross-linking the bacterial cell wall.

Received for publication, March 31, 2004 , and in revised form, June 1, 2004.

^* This work was supported by National Institutes of Health Grant GM61629. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed. Tel.: 574-631-2933; Fax: 574-631-6652; E-mail: mobashery{at}nd.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Chung, A. Antignac, C. Kim, and A. Tomasz Comparative Study of the Susceptibilities of Major Epidemic Clones of Methicillin-Resistant Staphylococcus aureus to Oxacillin and to the New Broad-Spectrum Cephalosporin Ceftobiprole Antimicrob. Agents Chemother., August 1, 2008; 52(8): 2709 - 2717. [Abstract] [Full Text] [PDF]

				L. R. R. Perez, C. Dias, and P. A. d'Azevedo Agar dilution and agar screen with cefoxitin and oxacillin: what is known and what is unknown in detection of meticillin-resistant Staphylococcus aureus J. Med. Microbiol., August 1, 2008; 57(8): 954 - 956. [Abstract] [Full Text] [PDF]

				S. Lemaire, C. Fuda, F. Van Bambeke, P. M. Tulkens, and S. Mobashery Restoration of Susceptibility of Methicillin-resistant Staphylococcus aureus to {beta}-Lactam Antibiotics by Acidic pH: ROLE OF PENICILLIN-BINDING PROTEIN PBP 2a J. Biol. Chem., May 9, 2008; 283(19): 12769 - 12776. [Abstract] [Full Text] [PDF]

				X. Fan, Y. Liu, D. Smith, L. Konermann, K. W. M. Siu, and D. Golemi-Kotra Diversity of Penicillin-binding Proteins: RESISTANCE FACTOR FmtA OF STAPHYLOCOCCUS AUREUS J. Biol. Chem., November 30, 2007; 282(48): 35143 - 35152. [Abstract] [Full Text] [PDF]

				D.-H. Kwon and C.-D. Lu Polyamine Effects on Antibiotic Susceptibility in Bacteria Antimicrob. Agents Chemother., June 1, 2007; 51(6): 2070 - 2077. [Abstract] [Full Text] [PDF]

				S. Lemaire, F. Van Bambeke, M.-P. Mingeot-Leclercq, Y. Glupczynski, and P. M. Tulkens Role of Acidic pH in the Susceptibility of Intraphagocytic Methicillin-Resistant Staphylococcus aureus Strains to Meropenem and Cloxacillin Antimicrob. Agents Chemother., May 1, 2007; 51(5): 1627 - 1632. [Abstract] [Full Text] [PDF]

				C. Fuda, D. Hesek, M. Lee, W. Heilmayer, R. Novak, S. B. Vakulenko, and S. Mobashery Mechanistic Basis for the Action of New Cephalosporin Antibiotics Effective against Methicillin- and Vancomycin-resistant Staphylococcus aureus J. Biol. Chem., April 14, 2006; 281(15): 10035 - 10041. [Abstract] [Full Text] [PDF]