当前位置： SCI文献检索 > PHYTOCHEMISTRY期刊下所有文献 > Sinapoyltransferases in the light of molecular evolution.

Sinapoyltransferases in the light of molecular evolution.

Abstract：

:Acylation is a prevalent chemical modification that to a significant extent accounts for the tremendous diversity of plant metabolites. To catalyze acyl transfer reactions, higher plants have evolved acyltransferases that accept beta-acetal esters, typically 1-O-glucose esters, as an alternative to the ubiquitously occurring CoA-thioester-dependent enzymes. Shared homology indicates that the beta-acetal ester-dependent acyltransferases are derived from a common hydrolytic ancestor of the Serine CarboxyPeptidase (SCP) type, giving rise to the name Serine CarboxyPeptidase-Like (SCPL) acyltransferases. We have analyzed structure-function relationships, reaction mechanism and sequence evolution of Arabidopsis 1-O-sinapoyl-beta-glucose:L-malate sinapoyltransferase (AtSMT) and related enzymes to investigate molecular changes required to impart acyltransferase activity to hydrolytic enzymes. AtSMT has maintained the catalytic triad of the hydrolytic ancestor as well as part of the H-bond network for substrate recognition to bind the acyl acceptor L-malate. A Glu/Asp substitution at the amino acid position preceding the catalytic Ser supports binding of the acyl donor 1-O-sinapoyl-beta-glucose and was found highly conserved among SCPL acyltransferases. The AtSMT-catalyzed acyl transfer reaction follows a random sequential bi-bi mechanism that requires both substrates 1-O-sinapoyl-beta-glucose and L-malate bound in an enzyme donor-acceptor complex to initiate acyl transfer. Together with the strong fixation of the acyl acceptor L-malate, the acquisition of this reaction mechanism favours transacylation over hydrolysis in AtSMT catalysis. The model structure and enzymatic side activities reveal that the AtSMT-mediated acyl transfer proceeds via a short-lived acyl enzyme complex. With regard to evolution, the SCPL acyltransferase clade most likely represents a recent development. The encoding genes are organized in a tandem-arranged cluster with partly overlapping functions. With other enzymes encoded by the respective gene cluster on Arabidopsis chromosome 2, AtSMT shares the enzymatic side activity to disproportionate 1-O-sinapoyl-beta-glucoses to produce 1,2-di-O-sinapoyl-beta-glucose. In the absence of the acyl acceptor L-malate, a residual esterase activity became obvious as a remnant of the hydrolytic ancestor. With regard to the evolution of Arabidopsis SCPL acyltransferases, our results suggest early neofunctionalization of the hydrolytic ancestor toward acyltransferase activity and acyl donor specificity for 1-O-sinapoyl-beta-glucose followed by subfunctionalization to recognize different acyl acceptors.

journal_name

Phytochemistry

journal_title

Phytochemistry

authors

Stehle F,Brandt W,Stubbs MT,Milkowski C,Strack D

doi

10.1016/j.phytochem.2009.07.023

subject

Has Abstract

pub_date

2009-10-01 00:00:00

pages

1652-62

issue

15-16

eissn

0031-9422

issn

1873-3700

pii

S0031-9422(09)00297-0

journal_volume

pub_type

杂志文章,评审

在线工具

Sinapoyltransferases in the light of molecular evolution.