Molecular Basis of Bacterial Cyanide Assimilation

University Of North Texas, Denton TX

Investigators

Abstract

Cyanide occurs as a natural biological poison in the environment. Over 2000 plants produce cyanide as a means of protecting against invading predators. Cyanide is also produced by certain fungi and bacteria, and its production by certain root-colonizing bacteria is believed to stimulate plant growth. Despite its occurrence in diverse biological settings, biochemical processes for cyanide metabolism are poorly understood. This project seeks to shed light on these processes leading to a better understanding of pathogenesis, plant-microbe interactions, and cyanide recycling in nature. The discovery that the initial steps in cyanide oxidation are mediated by a previously undescribed enzyme, cyanide oxygenase, and that this enzyme shares properties with another important enzyme having diverse roles in biology, namely, nitric oxide synthase, raises the prospect that new information on the properties and physiological roles of nitrogen-metabolizing enzymes in biology will be uncovered. A two-tiered research plan involving a collaborative effort with a senior faculty associate will be undertaken, with the objective being to characterize the proteins and genes constituting the ability of the bacterium, P. fluorescens (strain NCIMB 11764), to assimilate cyanide as a nitrogen source for growth. The biochemical pathway of cyanide breakdown in this organism will be determined, the enzymes and genes isolated and characterized at the amino acid/DNA sequence level, and the occurrence of related genes in other cyanide-metabolizing bacteria determined. The long-range goal of this work is to understand the molecular basis of cyanide breakdown making it possible to better predict the ecological role of cyanide producing and metabolizing bacteria, and the agricultural significance of cyanide in plant-microbe interactions. The proposed research will stress the multi-disciplinary training of students and post-doctorals impacting significantly the research and teaching atmosphere of the sponsoring institution.