Solution Structural Study of BlaI: Implications for the Repression of Genes Involved in β-Lactam Antibiotic Resistance

Melckebeke, Hélène Van; Vreuls, Christelle; Gans, Pierre; Filée, Patrice; Llabrès, Gabriel; Joris, Bernard; Simorre, Jean-Pierre

doi:10.1016/j.jmb.2003.09.005

Cited by 28 publications

(50 citation statements)

References 27 publications

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“…This is in accordance with the observation during NMR studies of B. licheniformis BlaI that the C-terminal segment His 83 -Glu 128 (see Fig. 1) is poorly resolved in solution (27). The three C-terminal helices are closely juxtaposed in MecI and intimately intertwine like two surface and side chain complementary protein superhelices.…”

Section: Structure Of Methicillin Repressor Within the Complex-likesupporting

confidence: 92%

“…This structural motif is followed by one or two ␤-hairpin wings (one in MecI), mostly engaged in minor and/or major groove interactions. The structure of MecI-DBD correlates well with that of isolated B. licheniformis BlaI-DBD, encompassing the first 82 residues (27). MecI-DD starts at Glu 74 and displays a right-handed superhelical ribbon made up by three consecutive helices, ␣4 to ␣6 (Fig.…”

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 54%

“…Indeed, these two repressor systems are interchangeable as regulators of transcription of both structural and regulatory genes in S. aureus, and they even form MecI-BlaI heterodimers (30 -32). B. licheniformis BlaI also can interact with mec (27). The promoter sequences indicate that MecI can recognize both palindromes on its own mec divergon separately and those of the S. aureus bla divergon, as the identified base sequence is conserved when compared with the Z dyad used here.…”

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 79%

“…indicates predicted protein; asterisks point to MecI side chains engaged in DNA recognition. In B. licheniformis BlaI, residues Ser 25 -Asn 25 have been found to form a b-strand (27). In MecI, this regular secondary structure element is reduced to a single residue, Ala 25 .…”

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 99%

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On the Transcriptional Regulation of Methicillin Resistance

García‐Castellanos

Mallorqui-Fernandez

Marrero

et al. 2004

Journal of Biological Chemistry

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Bacterial resistance to antibiotics poses a serious worldwide public health problem due to the high morbidity and mortality caused by infectious diseases. Most hospital-onset infections are associated with methicillin-resistant Staphylococcus aureus (MRSA) strains that have acquired multiple drug resistance to ␤-lactam antibiotics. In a response to antimicrobial stress, nearly all clinical MRSA isolates produce ␤-lactamase (BlaZ) and a penicillin-binding protein with low affinity for ␤-lactam antibiotics (PBP2a, also known as PBP2 or MecA). Both effectors are regulated by homologous signal transduction systems consisting of a sensor/transducer and a transcriptional repressor. MecI (methicillin repressor) blocks mecA but also blaZ transcription and that of itself and the co-transcribed sensor/transducer. The structure of MecI in complex with a cognate operator doublestranded DNA reveals a homodimeric arrangement with a novel C-terminal spiral staircase dimerization domain responsible for dimer integrity. Each protomer interacts with the DNA major groove through a winged helix DNA-binding domain and specifically recognizes the nucleotide sequence 5-Gua-Thy-Ade-X-Thy-3. This results in an unusual convex bending of the DNA helix. The structure of this first molecular determinant of methicillin resistance in complex with its target DNA provides insights into its regulatory mechanism and paves the way for new antimicrobial strategies against MRSA.

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Section: Structure Of Methicillin Repressor Within the Complex-likesupporting

confidence: 92%

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 54%

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 79%

Section: Structure Of Methicillin Repressor Within the Complex-likementioning

confidence: 99%

See 2 more Smart Citations

On the Transcriptional Regulation of Methicillin Resistance

García‐Castellanos

Mallorqui-Fernandez

Marrero

et al. 2004

Journal of Biological Chemistry

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“…In addition, the NMR solution structure is available for the B. licheniformis BlaI DNA-binding domain (20). This study describes the crystal structures of the S. aureus BlaR1 ␤-lactam sensor domain (hereafter referred to as BlaR S ) in both its apo and penicillinacylated forms.…”

mentioning

confidence: 99%

Crystal Structures of the Apo and Penicillin-acylated Forms of the BlaR1 β-Lactam Sensor of Staphylococcus aureus

Wilke

Hills

Zhang

et al. 2004

Journal of Biological Chemistry

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Staphylococcus aureus is among the most prevalent and antibiotic-resistant of pathogenic bacteria. The resistance of S. aureus to prototypal ␤-lactam antibiotics is conferred by two mechanisms: (i) secretion of hydrolytic ␤-lactamase enzymes and (ii) production of ␤-lactam-insensitive penicillin-binding proteins (PBP2a). Despite their distinct modes of resistance, expression of these proteins is controlled by similar regulation systems, including a repressor (BlaI/MecI) and a multidomain transmembrane receptor (BlaR1/MecR1). Resistance is triggered in response to a covalent binding event between a ␤-lactam antibiotic and the extracellular sensor domain of BlaR1/MecR1 by transduction of the binding signal to an intracellular protease domain capable of repressor inactivation. This study describes the first crystal structures of the sensor domain of BlaR1 (BlaR S ) from S. aureus in both the apo and penicillin-acylated forms. The structures show that the sensor domain resembles the ␤-lactam-hydrolyzing class D ␤-lactamases, but is rendered a penicillin-binding protein due to the formation of a very stable acyl-enzyme. Surprisingly, conformational changes upon penicillin binding were not observed in our structures, supporting the hypothesis that transduction of the antibiotic-binding signal into the cytosol is mediated by additional intramolecular interactions of the sensor domain with an adjacent extracellular loop in BlaR1.The evolution and dissemination of antibiotic resistance in pathogenic bacteria are a growing concern. Many of the antimicrobial "wonder drugs" society has come to rely on for the treatment of bacterial infections have been neutralized by new strains equipped with a variety of molecular countermeasures. Methicillin-resistant Staphylococcus aureus is a prominent example of this (1-3). Although ␤-lactam antibiotics such as penicillin have long been the drugs of choice for infections of S. aureus, current therapies for methicillin-resistant S. aureus infections now depend on distinct antibiotic classes such as glycopeptides to counter the increased resistance to penicillin and its derivatives. The recent emergence of glycopeptide-resistant strains of S. aureus (4, 5) underscores the need not only for the development of novel therapeutics, but for better understanding of the molecular mechanisms involved in antibiotic resistance.␤-Lactam antibiotics kill bacteria by inhibiting the cell wall transpeptidases (also known as penicillin-binding proteins (PBPs) 1 ) that are responsible for the essential cross-linking of peptidoglycan during synthesis of the rigid bacterial cell wall. Resistance to ␤-lactam antibiotics in S. aureus can be conferred by two mechanisms. In one case, ␤-lactamase enzymes are secreted from the bacterium to hydrolytically inactivate ␤-lactam antibiotics. Resistance of this form is encoded by the blaZ gene and is carried by Ͼ95% of S. aureus isolates (3). The second resistance mechanism is expression of PBP2a, a cell wall transpeptidase with broad-spectrum insensitivity to ␤-lacta...

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