1nrf
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(New page: 200px<br /><applet load="1nrf" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nrf, resolution 2.50Å" /> '''C-terminal domain of...)
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Revision as of 20:23, 20 November 2007
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C-terminal domain of the Bacillus licheniformis BlaR penicillin-receptor
Overview
As in several staphylococci, the synthesis of the Bacillus licheniformis, 749/I beta-lactamase is an inducible phenomenon regulated by a, signal-transducing membrane protein BlaR. The C-terminal domain of this, multimodular protein is an extracellular domain which specifically, recognizes beta-lactam antibiotics. When it binds a beta-lactam, a signal, is transmitted by the transmembrane region to the intracellular loops. In, response, the hydrolytic activity of the BlaR large cytoplasmic L3 loop is, induced, and a cascade of reactions is generated, leading to the, transcription of the beta-lactamase gene. Here, we describe the crystal, structure of the extracellular penicillin-receptor domain of BlaR, (residues 346-601) at 2.5 A resolution in order to understand why this, domain, whose folding is very similar to that of class D beta-lactamases, behaves as a highly sensitive penicillin-binding protein rather than a, beta-lactamase. Two residues of the BlaR C-terminal domain, Thr452 and, Thr542, modify the hydrophobic characteristic of the class D, beta-lactamase active site. Both residues seem to be in part responsible, for the lack of beta-lactamase activity of the BlaR protein due to the, stability of the acyl-enzyme. Although further experimental data are, needed to fully understand the transmembrane induction process, the, comparison of the BlaR sensor domain structure with those of class D, beta-lactamase complexes and penicillin-binding proteins provides, interesting elements to hypothesize on possible signal transmission, mechanisms.
About this Structure
1NRF is a Single protein structure of sequence from Bacillus licheniformis. Full crystallographic information is available from OCA.
Reference
Crystal structure of the sensor domain of the BlaR penicillin receptor from Bacillus licheniformis., Kerff F, Charlier P, Colombo ML, Sauvage E, Brans A, Frere JM, Joris B, Fonze E, Biochemistry. 2003 Nov 11;42(44):12835-43. PMID:14596597
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