Induction of extracellular (ECM) localized osmotin and other antifungal proteins in salt adapted cells and a salt regulated brain protein homologue associated with the promoter element of osmotin
Abstract
Tobacco (Nicotiana tabacum L. var Wisconsin 38) cells adapted to 428 mM NaCl (designated S-25) secreted three major proteins with molecular weight of 26, 29 and 40 kDa. These proteins have antifungal activities. The twenty six kilodalton protein was identified as osmotin whereas the identity of the 40 kDa protein has not been determined yet. The 29 kDa was purified to homogeneity. The protein composition analysis and partial internal amino acid sequence indicated that the 29 kDa protein was a member of class II chitinases. The purified 29 kDa protein has chitinase activity. Osmotin and chitinase are two of the five major groups of pythogenesis-related (PR) proteins. We propose that pathogen infection and salt adaptation may share a common signal pathway. A cDNA clone pCZ1, with a 1.1 kb insert, was isolated from a NaCl-adapted tobacco cell cDNA library that encodes a peptide which has a high amino acid sequence identity with bovine 14-3-3 protein, which was originally found as an abundant protein in the animal central nervous system. Recently, proteins with sequence identity to 14-3-3 protein have also been found in plants, insects and yeast, and appear to have diverse physiological functions. Similar to the bovine brain 14-3-3 protein, the recombinant pCZ1 protein stimulated ADP-ribosylation of protein substrate by the ADP-ribosyltransferase from the plant and animal pathogenic bacterium Pseudomonas aeruginosa. This recombinant protein also inhibited protein kinase C activity. The level of this mRNA transcript in tobacco cells was down-regulated upon adaptation to NaCl.
Degree
Ph.D.
Advisors
Bressan, Purdue University.
Subject Area
Molecular biology
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