Proteins in Response to Environmental Stress

Abstract

Last decade, remarkable progress was achieved in the field of environmental sciences, especially those related to biological functions against environmental stress. Recent progress has been focused on the transcriptional control of proteins, such as cytochrome P450, UDP-glucronosyltransferase, and metallothionein. Along with these studies, entirely new functions of some proteins were identified; for example heme oxygenase-1, originally isolated by the catalytic activity of heme, is nowadays recognized as one of the stress proteins. We are, therefore, interested in the relationship among proteins of body defense mechanisms; i. e., co-regulation of two (or more) distinct proteins, and why they should be under the same regulation.
One possible idea is that they are members of the defense system against active oxygen, which will be described by Drs. Sato and Inoue in a future review. Alternatively, they might have evolved from an ancestor of the defense system that originally protected from oxygen toxicity. Findings on AhR/Arnt and HIF1 systems demonstrating that they are members of the same PAS family seem to support this hypothesis. One of the missing links of the hypothesis is the so called oxygen sensor, suggesting (a) hemoprotein in 1988⁴⁾. A review by Dr. Ogawa on Bach1, the first vertebrate transcription factor controlled by heme, will provide on answers to the missing links.
Through this series of reviews, we have a rough map of the biological system against environmental stress to explore the new frontier of environmental science.