Linked Life Data

15531764

Source:http://linkedlifedata.com/resource/pubmed/id/15531764

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2005-1-24
pubmed:databankReference
pubmed:abstractText
Fatty acid catabolism by beta-oxidation mainly occurs in mitochondria and to a lesser degree in peroxisomes. Poly-unsaturated fatty acids are problematic for beta-oxidation, because the enzymes directly involved are unable to process all the different double bond conformations and combinations that occur naturally. In mammals, three accessory proteins circumvent this problem by catalyzing specific isomerization and reduction reactions. Central to this process is the NADPH-dependent 2,4-dienoyl-CoA reductase. We present high resolution crystal structures of human mitochondrial 2,4-dienoyl-CoA reductase in binary complex with cofactor, and the ternary complex with NADP(+) and substrate trans-2,trans-4-dienoyl-CoA at 2.1 and 1.75 A resolution, respectively. The enzyme, a homotetramer, is a short-chain dehydrogenase/reductase with a distinctive catalytic center. Close structural similarity between the binary and ternary complexes suggests an absence of large conformational changes during binding and processing of substrate. The site of catalysis is relatively open and placed beside a flexible loop thereby allowing the enzyme to accommodate and process a wide range of fatty acids. Seven single mutants were constructed, by site-directed mutagenesis, to investigate the function of selected residues in the active site thought likely to either contribute to the architecture of the active site or to catalysis. The mutant proteins were overexpressed, purified to homogeneity, and then characterized. The structural and kinetic data are consistent and support a mechanism that derives one reducing equivalent from the cofactor, and one from solvent. Key to the acquisition of a solvent-derived proton is the orientation of substrate and stabilization of a dienolate intermediate by Tyr-199, Asn-148, and the oxidized nicotinamide.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3068-77
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Structure and reactivity of human mitochondrial 2,4-dienoyl-CoA reductase: enzyme-ligand interactions in a distinctive short-chain reductase active site.
pubmed:affiliation
Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't