Reference "A gibberellin responsive wheat gene has homology to yeast carboxypeptidase Y"

Reference ID

9078

Title

A gibberellin responsive wheat gene has homology to yeast carboxypeptidase Y

Source

The Journal of biological chemistry, 1987, vol. 262, pp. 13726-13735

Authors (3)

Baulcombe-D-C	Barker-R-F
Jarvis-M-G

Abstract

An earlier report (Baulcombe, D. C., and Buffard, D. (1983) Planta 157, 493-501)
described the isolation of cDNA clones from mRNAs which are produced in
increased amounts when aleurone layers of wheat are treated with gibberellic
acid. It is shown here that for one of those cDNAs (2473) the change in level of
mRNA in aleurone parallels the change in level of alpha-amylase mRNA. This
result was obtained in experiments where the level of gibberellic acid was
varied and also when the mRNA was isolated from wheat genotypes which varied in
ability to respond to gibberellic acid. In contrast to this, the pattern of 2437
mRNA accumulation in immature grains and in leaf tissue was quite distinct from
the pattern of alpha-amylase mRNA accumulation. Analysis of wheat DNA showed
that the 2437 mRNA is encoded by a small family of genes located on the short
arm of the group 6 chromosomes. One member of this gene family was cloned and
sequenced. The coding sequence is interrupted by eight introns and encodes a
protein of Mr 55,433. By using hybridization probes from the 5' exon in an S1
nuclease protection assay it was shown that the 2437 mRNA was produced in
aleurones (coordinately with alpha-amylase) and in immature grains (not
coordinately with alpha-amylase). However, sequence comparison of 1 kilobase of
the 5'-flanking region with the sequence of alpha-amylase genes provided no
indication of the regulatory elements which would be active in aleurone cells.
The protein sequence deduced from the gene sequence has extensive homology with
the yeast carboxypeptidase Y, especially in the active site and substrate
binding regions. This homology is greater than with the carboxypeptidase I from
barley. It is suggested therefore that there are several types of
carboxypeptidase encoded in the cereal genome. The sequence of the 2437 protein
would represent one of these types and the barley carboxypeptidase I, another.