RUI: Genetic and Biochemical Analysis of Extracellular Complementation in Streptomyces coelicolor

Hofstra University, Hempstead NY

Investigators

Abstract

The goal of this research is to elucidate the structure of a detergent-like molecule, SapB, required for morphological differentiation in the bacterium Streptomyces coelicolor. The developmental cycle of this microbe begins with the germination of exospores resulting in the extension of multinucleate vegetative hyphae into a solid substrate. These form a dense network of filaments until signaled to differentiate into upwardly growing hydrophobic aerial hyphae, which then septate into spores to begin the cycle anew. Aerial hyphae formation is dependent on the products of the bald (bld) genes, which in turn regulate the production of SapB; bld mutants produce smooth colonies consisting only of vegetative substrate hyphae and are blocked in SapB biosynthesis. Extracellular complementation is observed when purified SapB is added to any bld mutant during growth on rich medium. SapB has a structural role in differentiation, functioning as a surfactant to facilitate upward growth of aerial filaments by releasing the surface tension at the colony/air interface. The gene(s) for SapB and its structure remain elusive. This program of research will use a biochemical approach to purify and elucidate the structure of SapB. Structural studies will begin with SapB purification. Its structure will then be determined by mass spectrometry and nuclear magnetic resonance studies to be performed in the laboratories of Drs. Charles Iden and Francis Picard, respectively at the State University of New York, Stony Brook. The resolution of the structure of SapB will advance the understanding of the role of extracellular communication in the morphological differentiation in this filamentous bacterium. In addition, this research will increase our appreciation of the role of intercellular communication in developmental processes in general. Undergraduate students will be involved in the project and trained in Molecular and Cell Biology.