Display Settings:

Format

Send to:

Choose Destination
Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6902-7.

An acyltransferase catalyzing the formation of diacylglucose is a serine carboxypeptidase-like protein.

Author information

  • 1Department of Plant Breeding, 252 Emerson Hall, Cornell University, Ithaca, NY 14853, USA.

Abstract

1-O-beta-acyl acetals serve as activated donors in group transfer reactions involved in plant natural product biosynthesis and hormone metabolism. However, the acyltransferases that mediate transacylation from 1-O-beta-acyl acetals have not been identified. We report the identification of a cDNA encoding a 1-O-beta-acylglucose-dependent acyltransferase functioning in glucose polyester biosynthesis by Lycopersicon pennellii. The acyltransferase cDNA encodes a serine carboxypeptidase-like protein, with a conserved Ser-His-Asp catalytic triad. Expression of the acyltransferase cDNA in Saccharomyces cerevisiae conferred the ability to disproportionate 1-O-beta-acylglucose to diacylglucose. The disproportionation reaction is regiospecific, catalyzing the conversion of two equivalents of 1-O-beta-acylglucose to 1, 2-di-O-acylglucose and glucose. Diisopropyl fluorophosphate, a transition-state analog inhibitor of serine carboxypeptidases, inhibited acyltransferase activity and covalently labeled the purified acyltransferase, suggesting the involvement of an active serine in the mechanism of the transacylation. The acyltransferase exhibits no carboxypeptidase activity; conversely, the serine carboxypeptidases we have tested show no ability to transacylate using 1-O-acyl-beta-glucoses. This acyltransferase may represent one member of a broader class of enzymes recruited from proteases that have adapted a common catalytic mechanism of catabolism and modified it to accommodate a wide range of group transfer reactions used in biosynthetic reactions of secondary metabolism. The abundance of serine carboxypeptidase-like proteins in plants suggests that this motif has been used widely for metabolic functions.

PMID:
10829071
[PubMed - indexed for MEDLINE]
PMCID:
PMC18773
Free PMC Article

Images from this publication.See all images (8)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk