title: Heterologous expression of an uncharacterized universal stress protein gene (SbUSP) from the extreme halophyte, Salicornia brachiata, which confers salt and osmotic tolerance to E. coli.
abstract: Salicornia brachiata is an extreme halophyte considered to be a rich source of stress responsive genes and an EST database revealed that 30% of its genes are uncharacterized. In order to ascertain its function, a gene (Sal-E-56) of unknown function was made full length using RACE, cloned and characterized. The full length gene (873 bp; accession no. KF164282) contained an open reading frame (ORF) of 486 bp encoding for a protein that belongs to the universal stress protein (USP) family that was named SbUSP. The SbUSP interacted with adenosine monophosphate and exhibited characteristic motifs, phosphorylation, glycosylation and ATP binding sites. Further, in-silico analyses suggested a probable role in metabolic process of phosphate-containing compounds including signal transduction. In planta transcript profiling exhibited a significant expression response (7.8-fold) to salt stress, additionally abundant of SbUSP transcripts were observed during drought, heat and cold stress, reaching a maximum increase of 3.66-, 2.64- and 2.14-fold, respectively, at 12 or 24h. The heterologous expression of this gene in Escherichia coli provided enhanced stress tolerance and recombinant cells have higher growth rate compared to vector alone and showed growth at up to a 10(-5) dilution in the spot assay. It was predicted that SbUSP may be directly involved in tolerance mechanisms or function as a molecular switch (signaling molecule) to activate the stress adaptive mechanisms. However, further investigation will be required to determine its role as a molecular switch and mode of action during stress.
authors.affiliation: Discipline of Marine Biotechnology and Ecology, CSIR-Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar, Gujarat 364002, India.
authors.forename: Pushpika
authors.initials: P
authors.lastname: Udawat
authors.affiliation: Discipline of Marine Biotechnology and Ecology, CSIR-Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar, Gujarat 364002, India. Electronic address: avinash@csmcri.org.
authors.forename: Avinash
authors.initials: A
authors.lastname: Mishra
authors.affiliation: Discipline of Marine Biotechnology and Ecology, CSIR-Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar, Gujarat 364002, India. Electronic address: bjha@csmcri.org.
authors.forename: Bhavanath
authors.initials: B
authors.lastname: Jha
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019663:Chenopodiaceae / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D018506:Gene Expression Regulation, Plant; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D030781:Organisms, Genetically Modified; D064587:Osmoregulation / Q000235:genetics*; D055049:Salt Tolerance / Q000235:genetics*; D055051:Salt-Tolerant Plants / Q000235:genetics*; D014161:Transduction, Genetic
chemical_list: D006360:Heat-Shock Proteins
keywords: Abiotic stress; EST; GST; Halophytes; ICP; Osmotic tolerance; RACE; Salt stress; Salt tolerance; USP; expressed sequence tag; glutathione S-transferase; inductive coupled plasma; qRT PCR; quantitative real time PCR; rapid amplification of cDNA ends; universal stress protein