Abstract
Production of active hydrogenase by Escherichia coli requires several gene products. One of the essential genes, hydB, is encoded by a DNA fragment of approximately 1.0 kilobase. The hydB gene produced a protein with an apparent molecular weight of 32,000. The hydB gene was transcribed only under anaerobic conditions. Oxygen and nitrate repressed transcription of this gene. hydB gene transcription also required sigma 60, the product of the rpoN gene.