Use of a lacZ fusion to study transcriptional regulation of the Rhodobacter capsulatus hemA gene

Abstract

An EcoRI fragment containing the Rhodobacter capsulatus hamA promoter has been cloned into a lacZ translational fusion vector. The resulting plasmid produced a hemA-lacZ fusion protein with a molecular mass of 147 000. Expression of the hemA-lacZ fusion, as measured by production of β-galactosidase, was regulated 2- to 3-fold by oxygen tension. The unexpectedly small change in β-galactosidase levels suggests that transcriptional regulation of the hemA gene is not the major factor in oxygen-mediated control of porphyrin synthesis.