Reference "Purification, characterization and gene structure of (1-->3)-beta-glucanase isoenzyme GIII from barley (Hordeum vulgare)"

Reference ID

8626

Title

Purification, characterization and gene structure of (1-->3)-beta-glucanase isoenzyme GIII from barley (Hordeum vulgare)

Source

European journal of biochemistry / FEBS, 1992, vol. 209, pp. 103-109

Authors (3)

Wang-J	Xu-P
Fincher-G-B

Abstract

A new member of the barley (1-->3)-beta-glucan glucanohydrolase family of
enzymes has been purified from extracts of germinated grain and young seedlings
by fractional precipitation with ammonium sulphate, ion-exchange chromatography,
chromatofocussing and gel-filtration chromatography. The enzyme, which has been
designated (1-->3)-beta-glucanase isoenzyme GIII, is a basic protein with an
apparent molecular mass of 32 000 Da. Oligosaccharide products released by the
enzyme during hydrolysis of the (1-->3)-beta-glucan, laminarin, indicate that
the enzyme is an endohydrolase. A 2349-bp fragment of barley genomic DNA has
been isolated and identified as the gene encoding the (1-->3)-beta-glucanase
isoenzyme GIII. The open reading frame encoding the isoenzyme is interrupted by
a single intron of 180 bp that splits a codon in the putative signal-peptide
region. Northern-blot analyses with gene-specific probes indicate that the (1-->3)-beta-
glucanase isoenzyme GIII mRNA accumulates in developing leaves; no mRNA
transcripts were detected in the aleurone or scutellum of germinated grain, or
in mature vegetative tissues. Although plant (1-->3)-beta-glucanases are
generally classified as 'pathogenesis-related' proteins, the physiological
function of the barley (1-->3)-beta-glucanase isoenzyme GIII is unclear.