2c7y
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PLANT ENZYME
OverviewOverview
Crystal structures of peroxisomal Arabidopsis thaliana 3-ketoacyl-CoA, thiolase (AtKAT), an enzyme of fatty acid beta-oxidation, are reported., The subunit, a typical thiolase, is a combination of two similar, alpha/beta domains capped with a loop domain. The comparison of AtKAT with, the Saccharomyces cerevisiae homologue (ScKAT) structure reveals a, different placement of subunits within the functional dimers and that a, polypeptide segment forming an extended loop around the open catalytic, pocket of ScKAT converts to alpha-helix in AtKAT, and occludes the active, site. A disulfide is formed between Cys192, on this helix, and Cys138, a, catalytic residue. Access to Cys138 is determined by the structure of this, polypeptide segment. AtKAT represents an oxidized, previously unknown, inactive form, whilst ScKAT is the reduced and active enzyme. A high level, of sequence conservation is observed, including Cys192, in eukaryotic, peroxisomal, but not mitochondrial or prokaryotic KAT sequences, for this, labile loop/helix segment. This indicates that KAT activity in peroxisomes, is influenced by a disulfide/dithiol change linking fatty acid, beta-oxidation with redox regulation.
About this StructureAbout this Structure
2C7Y is a Single protein structure of sequence from Arabidopsis thaliana. Active as Acetyl-CoA C-acyltransferase, with EC number 2.3.1.16 Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of a plant 3-ketoacyl-CoA thiolase reveals the potential for redox control of peroxisomal fatty acid beta-oxidation., Sundaramoorthy R, Micossi E, Alphey MS, Germain V, Bryce JH, Smith SM, Leonard GA, Hunter WN, J Mol Biol. 2006 Jun 2;359(2):347-57. Epub 2006 Mar 29. PMID:16630629
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