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Control of Gene Expression During Differentiation and Heat Shock in Microorganisms

Abstract

The purpose of this research project is to investigate molecular aspects related to the control of gene expression during differentiation and during heat stress in microorganisms using two model systems: the gram-negative bacterium Caulobacter crescentus and the aquatic fungus Blastocladiella emersonii. In Caulobacter crescentus, we are studying the expression and function of two operons encoding heat shock proteins: dnaKJ and groESL, which are regulated during the cell cycle of the bacterium and by temperature. Molecular analysis of these two operons will allow us to understand the mechanisms involved not only in the control of expression of these genes but also of the heat shock response in Caulobacter. Analysis of the role of these genes utilizing molecular genetics, will lead to the understanding of their functions during heat shock and throughout the cell cycle of the bacterium. The characterization of the hsp60 gene from Balstocladiella emersonii complements previous studies in our laboratory with the hsp70 gene. The purpose of these studies is to investigate the sic-acting elements, as well as the trans-acting elements, involved in the induction of heat shock genes in B. emersonii, which are apparently different from those described in yeast and Drosophila. The cAMP-dependent protein kinase, whose expression we have demonstrated to be regulated at a transcriptional level during the life cycle of the fungus, will be in this project analysed in regard to its degradation. The proteolytic system involved in the degradation of the R and C subunits of B. emersonii PKA will be characterized by the production in E. coli of R and C subunits containing site-directed mutations, which will be used as substrates for the proteolytic activity purified from zoospores. The role of the system calcium-Calmodulin during differentiation and development will be investigated through the cloning and characterization of the gene enconding Blastocladiella calmodulin and analysing the effects of various calcium antagonists in the life cycle of the fungus. Two genes enconding isoforms of a P-type ATPase from B. emersonii were recently isolated in our laboratory and are being characterized. The ions transported by these ATPases will also be investigated. (AU)

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VEICULO: TITULO (DATA)
VEICULO: TITULO (DATA)