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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-7-4
pubmed:databankReference
pubmed:abstractText
Three polyketide synthase genes (PKS1, PKS2, PKS3) from cell suspension cultures of raspberry (Rubus idaeus L. cv. Royalty) were characterized. They showed high similarity in both their nucleotide and deduced amino acid sequences. All three proteins contain the amino acid residues identified in previous work as essential for chalcone synthase (CHS) function. Enzyme activities were investigated after heterologous expression in Escherichia coli. RiPKS1 is a typical naringenin CHS that synthesizes the chalcone as the main reaction product, and p-coumaryltriacetic acid lactone (CTAL) as a minor by-product. RiPKS3 differed from RiPKS1 in four positions (K49R, M64R, P120L, V188A), and the products in vitro were predominantly CTAL and low levels of chalcone. RiPKS2 had the same four differences from RiPKS1 as RiPKS3, but in addition two further exchanges (R259H, F344L), and the protein had no detectable enzyme activity. Experiments with RiPKS1 containing either 259H or 344L showed that each of the exchanges was sufficient to completely eliminate enzyme activity. These experiments identify amino acid residues in CHS which are important for folding of the tetraketide intermediate to the chalcone (PKS3) and which are in general essential for CHS activity (PKS2). The possible functions of these residues are discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0167-4412
pubmed:author
pubmed:issnType
Print
pubmed:volume
46
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1-15
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:11437245-Amino Acid Sequence, pubmed-meshheading:11437245-Cloning, Molecular, pubmed-meshheading:11437245-DNA, Plant, pubmed-meshheading:11437245-Escherichia coli, pubmed-meshheading:11437245-Exons, pubmed-meshheading:11437245-Fruit, pubmed-meshheading:11437245-Gene Expression Regulation, Enzymologic, pubmed-meshheading:11437245-Gene Expression Regulation, Plant, pubmed-meshheading:11437245-Introns, pubmed-meshheading:11437245-Isoenzymes, pubmed-meshheading:11437245-Molecular Sequence Data, pubmed-meshheading:11437245-Multienzyme Complexes, pubmed-meshheading:11437245-Phylogeny, pubmed-meshheading:11437245-Recombinant Proteins, pubmed-meshheading:11437245-Sequence Alignment, pubmed-meshheading:11437245-Sequence Analysis, DNA, pubmed-meshheading:11437245-Sequence Homology, Amino Acid
pubmed:year
2001
pubmed:articleTitle
Molecular and biochemical characterization of three aromatic polyketide synthase genes from Rubus idaeus.
pubmed:affiliation
Institute of Food Science, Cornell University, Geneva, NY 14456, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't