9507509 Staben The goal of this research is to determine the molecular basis of the mating type-specific responses in the Ascomycete fungus, Neurospora crassa. The N. crassa mating type locus regulates critical aspects of fungal development and sexual reproduction that are widely conserved in fungi. This research focuses upon the biochemical and biological functions of the mating type polypeptides, particularly the MT a-l polypeptide encoded by the mt a idiomorph of the mating type locus. The MT a-1 polypeptide appears to be the only product of the mt a idiomorph essential to determine a mating type. This polypeptide binds specific DNA sequences. It is proposed that MT a-l regulates the transcriptional activity of the DNA segments that it binds. In addition, MT a-l has separable properties essential for its vegetative incompatibility function. The biochemical functions of MT a-1 in both mating and vegetative incompatibility are likely to be modulated after mating or after heterokaryon formation by interaction with A-specific products. At least one of these polypeptides, MT A-3, binds to DNA fragments that also bind MT a-1 in vitro. The proposed research will determine whether MT a-l directly interacts with products of the mt A idiomorph, whether these interactions affect DNA binding by MT a-l, and whether such interactions have biological consequences. This research will involve molecular genetic and biochemical characterization of the functions of MT a-l and its interactions with other developmental regulators in vegetative incompatibility and mating responses. The research will involve the creation of novel genetic tools including libraries of Neurospora genomic or cDNA suitable for yeast-based two-hybrid screens for interacting gene products. MT a-1 is a member of an important class of DNA binding proteins and developmental regulators, the HMG box proteins. MT a-l, unlike many members of this family, is amenable to genetic analysis. These studies will also yield valuable insi ghts into fundamental aspects of developmental biology of filamentous fungi like Neurospora. %%% The filamentous ascomycetes include important animal and plant pathogenic fungi. In this project the investigator will study the mating system of one such fungus, Neurospora crassa. His work will further our understanding of what signals control certain mating proteins and how these proteins, in turn, lead to the developmental consequences of mating. The insights into mating may be crucial in applied concerns such as control of infection as well as to understanding basic biological phenomena, such as how control of mating may relate to species barriers and to speciation mechanisms within the ascomycetes. *** ??
