1hd8: Difference between revisions
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==Overview== | ==Overview== | ||
Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as a, d-alanine carboxypeptidase, cleaving the C-terminal d-alanine residue from, cell wall peptides. Like all PBPs, PBP 5 forms a covalent acyl-enzyme, complex with beta-lactam antibiotics; however, PBP 5 is distinguished by, its high rate of deacylation of the acyl-enzyme complex (t(12), approximately 9 min). A Gly-105 --> Asp mutation in PBP 5 markedly impairs, this beta-lactamase activity (deacylation), with only minor effects on, acylation, and promotes accumulation of a covalent complex with peptide, substrates. To gain further insight into the catalytic mechanism of PBP 5, we determined the three-dimensional structure of the G105D mutant form of, soluble PBP 5 (termed sPBP 5') at 2.3 A resolution. The structure ... | Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as a, d-alanine carboxypeptidase, cleaving the C-terminal d-alanine residue from, cell wall peptides. Like all PBPs, PBP 5 forms a covalent acyl-enzyme, complex with beta-lactam antibiotics; however, PBP 5 is distinguished by, its high rate of deacylation of the acyl-enzyme complex (t(12), approximately 9 min). A Gly-105 --> Asp mutation in PBP 5 markedly impairs, this beta-lactamase activity (deacylation), with only minor effects on, acylation, and promotes accumulation of a covalent complex with peptide, substrates. To gain further insight into the catalytic mechanism of PBP 5, we determined the three-dimensional structure of the G105D mutant form of, soluble PBP 5 (termed sPBP 5') at 2.3 A resolution. The structure is, composed of two domains, a penicillin binding domain with a striking, similarity to Class A beta-lactamases (TEM-1-like) and a domain of unknown, function. In addition, the penicillin-binding domain contains an active, site loop spatially equivalent to the Omega loop of beta-lactamases. In, beta-lactamases, the Omega loop contains two amino acids involved in, catalyzing deacylation. This similarity may explain the high, beta-lactamase activity of wild-type PBP 5. Because of the low rate of, deacylation of the G105D mutant, visualization of peptide substrates bound, to the active site may be possible. | ||
==About this Structure== | ==About this Structure== | ||
1HD8 is a | 1HD8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/Serine-type_D-Ala-D-Ala_carboxypeptidase Serine-type D-Ala-D-Ala carboxypeptidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.16.4 3.4.16.4] Structure known Active Site: S44. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1HD8 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: peptidoglycan synthesis]] | [[Category: peptidoglycan synthesis]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 15:10:19 2007'' | ||
