Isolation and characterisation of a LEA-like protein from yeast (Saccharomyces cerevisiae)
type: CreativeWork
description: LEA proteins are plant proteins that are characteristically hydrophilic and soluble at elevated temperature. The consistent correlation between desiccation tolerance in orthodox seed tissue and an accumulation of LEA proteins suggests that these proteins play an important role in protecting cells from desiccation induced damage. Yeast (Saccharomyces cerevisiae) has been known to desiccate as part of its normal growth cycle and to remain viable after long periods in the desiccated state. As a result of these properties this project was designed to investigate the presence of LEA-like proteins in yeast. A protein was isolated from baker’s yeast that fulﬁls the requirements for being a LEA protein. This protein, with a molecular mass of 11 kDa, was found to be the most prevalent heat soluble protein in the yeast extract. Antibodies raised against LEA group I proteins recognised this 11 kDa yeast protein in the total extract but failed to recognise the protein after heat treatment at 80°C for 10 min. Amino acid analysis showed that the ll kDa protein was highly hydrophilic - a characteristic of LEA proteins. The protein was partially sequenced (10 cycles) after CNBr digestion and the sequence obtained was compared with the sequence of known proteins in the Stanford databank. Only one protein, HSP 12, was identiﬁed to be 100 % homologous to the obtained sequence without the introduction of gaps. Despite a previous report that HSP 12 is a heat shock protein, HSP 12 was present in a reduced concentration in yeast grown at 37 °C compared with yeast grown at 30 °C. HSP 12 was found to increase in concentration after entry into stationary phase - a time when nutrients are limiting and the yeast is preparing to reduce its water content and sporulate. This might be considered equivalent to plant seed maturation - the stage when LEA proteins are synthesised. Moreover, growth conditions that have been reported to stimulate LEA protein biosynthesis in plants also stimulated HSP 12…
abstract: LEA proteins are plant proteins that are characteristically hydrophilic and soluble at elevated temperature. The consistent correlation between desiccation tolerance in orthodox seed tissue and an accumulation of LEA proteins suggests that these proteins play an important role in protecting cells from desiccation induced damage. Yeast (Saccharomyces cerevisiae) has been known to desiccate as part of its normal growth cycle and to remain viable after long periods in the desiccated state. As a result of these properties this project was designed to investigate the presence of LEA-like proteins in yeast. A protein was isolated from baker’s yeast that fulﬁls the requirements for being a LEA protein. This protein, with a molecular mass of 11 kDa, was found to be the most prevalent heat soluble protein in the yeast extract. Antibodies raised against LEA group I proteins recognised this 11 kDa yeast protein in the total extract but failed to recognise the protein after heat treatment at 80°C for 10 min. Amino acid analysis showed that the ll kDa protein was highly hydrophilic - a characteristic of LEA proteins. The protein was partially sequenced (10 cycles) after CNBr digestion and the sequence obtained was compared with the sequence of known proteins in the Stanford databank. Only one protein, HSP 12, was identiﬁed to be 100 % homologous to the obtained sequence without the introduction of gaps. Despite a previous report that HSP 12 is a heat shock protein, HSP 12 was present in a reduced concentration in yeast grown at 37 °C compared with yeast grown at 30 °C. HSP 12 was found to increase in concentration after entry into stationary phase - a time when nutrients are limiting and the yeast is preparing to reduce its water content and sporulate. This might be considered equivalent to plant seed maturation - the stage when LEA proteins are synthesised. Moreover, growth conditions that have been reported to stimulate LEA protein biosynthesis in plants also stimulated HSP 12…
author: Mtwisha, Linda
language: eng
date published: 1998
date modified: 2026-07-22T22:22:50Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Molecular and Cell Biology

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/9685