Chloramphenicol acetyltransferase (or CAT) is a bacterialenzyme (EC 2.3.1.28)[1] that detoxifies the antibioticchloramphenicol and is responsible for chloramphenicol resistance in bacteria.[2] This enzyme covalently attaches an acetyl group from acetyl-CoA to chloramphenicol, which prevents chloramphenicol from binding to ribosomes. A histidine residue, located in the C-terminal section of the enzyme, plays a central role in its catalytic mechanism.
Chloramphenicol acetyltransferase
Ribbon diagram of the chloramphenicol acetyltransferase trimer with chloramphenicol bound. From PDB: 3CLA.
The crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined. CAT is a trimer of identical subunits (monomer Mr 25,000) and the trimeric structure is stabilised by a number of hydrogen bonds, some of which result in the extension of a beta-sheet across the subunit interface. Chloramphenicol binds in a deep pocket located at the boundary between adjacent subunits of the trimer, such that the majority of residues forming the binding pocket belong to one subunit while the catalytically essential histidine belongs to the adjacent subunit. His195 is appropriately positioned to act as a general base catalyst in the reaction, and the required tautomeric stabilisation is provided by an unusual interaction with a main-chain carbonyl oxygen.[3]
Applicationedit
CAT is used as a reporter system to measure the level of a promoter or its tissue-specific expression. The CAT assay involves monitoring acetylation of radioactively labeled chloramphenicol on a TLC plate; CAT activity is determined by looking for the acetylated forms of chloramphenicol, which have a significantly increased migration rate as compared to the unacetylated form.[4]
Referencesedit
^Engel J, Prockop DJ (1991). "The zipper-like folding of collagen triple helices and the effects of mutations that disrupt the zipper". Annu. Rev. Biophys. Biophys. Chem. 20 (1): 137–152. doi:10.1146/annurev.bb.20.060191.001033. PMID 1867713.
^Shaw WV, Packman LC, Burleigh BD, Dell A, Morris HR, Hartley BS (1979). "Primary structure of a chloramphenicol acetyltransferase specified by R plasmids". Nature. 282 (5741): 870–2. Bibcode:1979Natur.282..870S. doi:10.1038/282870a0. PMID 390404. S2CID 2038024.
^Leslie AG (1990). "Refined crystal structure of type III chloramphenicol acetyltransferase at 1.75 A resolution". J. Mol. Biol. 213 (1): 167–186. doi:10.1016/S0022-2836(05)80129-9. PMID 2187098.
^Gorman, CM; Moffat LF; Howard BH (1982). "Recombinant genomes which express chloramphenicol acetyltransferase in mammalian cells". Mol. Cell. Biol. 2 (9): 1044–1051. doi:10.1128/MCB.2.9.1044. PMC369897. PMID 6960240.
This article incorporates text from the public domain Pfam and InterPro: IPR001707
April 14, 2024
chloramphenicol, acetyltransferase, bacterial, enzyme, that, detoxifies, antibiotic, chloramphenicol, responsible, chloramphenicol, resistance, bacteria, this, enzyme, covalently, attaches, acetyl, group, from, acetyl, chloramphenicol, which, prevents, chloram. Chloramphenicol acetyltransferase or CAT is a bacterial enzyme EC 2 3 1 28 1 that detoxifies the antibiotic chloramphenicol and is responsible for chloramphenicol resistance in bacteria 2 This enzyme covalently attaches an acetyl group from acetyl CoA to chloramphenicol which prevents chloramphenicol from binding to ribosomes A histidine residue located in the C terminal section of the enzyme plays a central role in its catalytic mechanism Chloramphenicol acetyltransferaseRibbon diagram of the chloramphenicol acetyltransferase trimer with chloramphenicol bound From PDB 3CLA IdentifiersSymbolCATPfamPF00302InterProIPR001707PROSITEPDOC00093SCOP23cla SCOPe SUPFAMAvailable protein structures Pfam structures ECOD PDBRCSB PDB PDBe PDBjPDBsumstructure summaryPDB1q23 G 6 209 1pd5 A 6 209 1noc B 6 209 1qca 1 205 3cla 1 205 4cla 1 205 1cia 1 205 1cla 1 205 2cla 1 205Chloramphenicol acetyltransferaseIdentifiersEC no 2 3 1 28CAS no 9040 07 7DatabasesIntEnzIntEnz viewBRENDABRENDA entryExPASyNiceZyme viewKEGGKEGG entryMetaCycmetabolic pathwayPRIAMprofilePDB structuresRCSB PDB PDBe PDBsumGene OntologyAmiGO QuickGOSearchPMCarticlesPubMedarticlesNCBIproteinsThe crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined CAT is a trimer of identical subunits monomer Mr 25 000 and the trimeric structure is stabilised by a number of hydrogen bonds some of which result in the extension of a beta sheet across the subunit interface Chloramphenicol binds in a deep pocket located at the boundary between adjacent subunits of the trimer such that the majority of residues forming the binding pocket belong to one subunit while the catalytically essential histidine belongs to the adjacent subunit His195 is appropriately positioned to act as a general base catalyst in the reaction and the required tautomeric stabilisation is provided by an unusual interaction with a main chain carbonyl oxygen 3 Application editCAT is used as a reporter system to measure the level of a promoter or its tissue specific expression The CAT assay involves monitoring acetylation of radioactively labeled chloramphenicol on a TLC plate CAT activity is determined by looking for the acetylated forms of chloramphenicol which have a significantly increased migration rate as compared to the unacetylated form 4 References edit Engel J Prockop DJ 1991 The zipper like folding of collagen triple helices and the effects of mutations that disrupt the zipper Annu Rev Biophys Biophys Chem 20 1 137 152 doi 10 1146 annurev bb 20 060191 001033 PMID 1867713 Shaw WV Packman LC Burleigh BD Dell A Morris HR Hartley BS 1979 Primary structure of a chloramphenicol acetyltransferase specified by R plasmids Nature 282 5741 870 2 Bibcode 1979Natur 282 870S doi 10 1038 282870a0 PMID 390404 S2CID 2038024 Leslie AG 1990 Refined crystal structure of type III chloramphenicol acetyltransferase at 1 75 A resolution J Mol Biol 213 1 167 186 doi 10 1016 S0022 2836 05 80129 9 PMID 2187098 Gorman CM Moffat LF Howard BH 1982 Recombinant genomes which express chloramphenicol acetyltransferase in mammalian cells Mol Cell Biol 2 9 1044 1051 doi 10 1128 MCB 2 9 1044 PMC 369897 PMID 6960240 Portal nbsp Biology This article incorporates text from the public domain Pfam and InterPro IPR001707 Retrieved from https en wikipedia org w index php title Chloramphenicol acetyltransferase amp oldid 1082000934, wikipedia, wiki, book, books, library,
