NSF Award
9723565
9723565 Lowry The adaptation to the lack of oxygen from a regulatory point of view is the inverse of the adaptation to the presence of oxygen. The family of anaerobic genes is composed of at least three subsets, two of which are negatively regulated by heme, and another which is negatively regulated by unsaturated fatty acid (both heme and UFA can only be synthesized in the presence of oxygen). This project will focus on the DAN1 anaerobic gene in yeast which is regulated in parallel with the members of a fairly well studied anaerobic regulon known as the hypoxic genes. DAN1 and the members of hypoxic regulon are all negatively regulated by heme, which serves as a signal for the presence of oxygen in yeast. Preliminary evidence indicates that regulation of DAN1 is governed by a different set of proteins than those which control the hypoxic genes. In particular the ROX1 repressor, which controls the hypoxic genes is not involved in DAN1 regulation. In this project three factors, encoded by genes designated ROX7, ROX8, and ROX9, which have been identified genetically as regulators of DAN1 will be cloned and characterized. The objective will be to discover the mechanism by which heme regulates DAN1. It is apparent that there are at least three different pathways sensitive to heme regulation. Two are well known, involving the regulators HAP1 and HAP2/3/4. Two more have been inferred recently, one which is involved (along with HAP1 ) in heme induction of ROX1, and another which regulates DAN1. A significant objective of this project will be to place DAN1 in the context of the three pathways, with a particular emphasis on the mechanism(s) by which heme is sensed at the molecular level. The mechanism of regulation of DAN1 will be studied in terms of the interactions of the identified regulatory factors with each other and with the regulatory sites which have been identified in the regulatory region of DANI. The limited objective of this project is to get a broad outline of the mechanism with a view to deeper inquiry in the future. %%% This project will focus on the DAN1 anaerobic gene in yeast, which is negatively regulated by heme in parallel with a fairly well studied family of anaeroic genes known as the hypoxic genes. Heme functions as a ligand in many different contexts in biology, both catalytically and also as a regulator. The mechanism of regulation of DAN1 will be studied in terms of the interactions of the identified regulatory factors with each other and with the regulatory region of DAN1. The limited objective of this project is to get a broad outline of the regulatory mechanism with a view to deeper inquiry in the future. ***
