Linked Life Data

16087700

Source:http://linkedlifedata.com/resource/pubmed/id/16087700

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
419
pubmed:dateCreated
2005-8-15
pubmed:abstractText
Dihydroflavonol 4-reductase (DFR) is the first committed enzyme of the anthocyanin and condensed tannin pathways. Several DFR cDNAs have been cloned, and different specificities of DFR isozymes in the substrate hydroxylation patterns have been reported, but only fragmentary knowledge of DFR gene organization is available. Reported here is a comprehensive analysis of DFRs of a model legume, Lotus japonicus. A total of five DFR genes were found to form a cluster within a 38 kb region in the L. japonicus genome, whereas six cDNAs, including two splicing variants resulting from a transversion at a splicing acceptor site, were cloned. All the genes were expressed, with different organ specificities, in the mature plant. Three of the DFR proteins heterologously expressed in Escherichia coli showed catalytic activity, and their substrate preferences agreed with the variation of a specific active site residue (Asp or Asn) reported to control the specificity. The hydroxylation patterns of anthocyanidins and condensed tannin units in the stems did not reflect the substrate specificity of the expressed isozymes, implying complex regulation mechanisms in the biosynthesis. The two splicing variants and one DFR with Ser at the specificity-controlling position failed to show the activity, but a revertant protein replacing the unusual splicing restored the activity. The phylogenetic tree, constructed with known DFR sequences, showed evolutionary divergence of some of the DFR genes prior to the plant speciation. This work affords the basis for genetic and biochemical studies on the diversity of DFR and the flavonoid products.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-0957
pubmed:author
pubmed:issnType
Print
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2573-85
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
A comprehensive analysis of six dihydroflavonol 4-reductases encoded by a gene cluster of the Lotus japonicus genome.
pubmed:affiliation
Department of Applied Biological Sciences, Nihon University, Fujisawa, Kanagawa 252-8510, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't