Streptomyces scabies, a gram positive soil bacterium, is the causative organism for scab disease on a variety of underground vegetables. The pathogen produces an extracellular esterase which may be involved in the breakdown of suberin, a waxy polyester compound that covers the surface of the tuber and thus protect the plant against moisture and possibly pathogen invasion. This esterase has been purified and characterized. Its production is induced by zinc which was found to be a component of suberin. The goal of the research is to elucidate the mechanism by which zinc effects this induction. The esterase gene will be cloned and its sequence determined. Transcription of the gene, the stability and translation of the esterase mRNA, and processing/secretion of the esterase will be tested for zinc dependence. Secretion of this esterase by the pathogen will also be studied. This research will provide important basic information of the mechanisms of gene expression and protein secretion in Streptomyces scabies, an agriculturally important pathogen. The results will enhance our understanding of the mechanisms of gene regulation and the molecular biology of host-pathogen interactions. They may also be applied to the protection of economic crops against infection by pathogenic organisms.
