Donohue Lab Home Page

Home of Rhodobacter sphaeroides at the University of Wisconsin-Madison

Rhodobacter sphaeroides cytochrome c₂ crystal structure coordinates determined by Herb Axelrod, UCSD

On the shores of beautiful Lake Mendota

Research Interests

Our lab is interested in energy generation by the purple, non-sulfur bacterium Rhodobacter sphaeroides. Specifically we focus on five topics:

The transcriptional regulation of cycA, the gene that encodes cytochrome c₂, a well studied protein with important functions in both aerobic and photosynthetic electron transport. This includes defining cycA promoters that are recognized by individual forms of RNA polymerase holoenzyme, determining how function of a major promoter is increased under anaerobic conditions and indentifying how an alternative sigma factor (RpoE) alters cycA transcription in response to metabolic cues that effect heme availability.

Assembly of cytochrome c₂ as an electron carrier, including functions required for covalent attachment of heme, signal peptide cleavage, and the role of ccm gene products in c-type cytochrome maturation.

The function of isocytochrome c₂, both as an alternate electron donor to the photosynthetic reaction center and in pathways that generate formaldehyde as an intermediate.

How this bacterium senses formaldehyde, assimilates it into cellular carbon and controls genes required for its oxidation.

The function and regulation of aerobically expressed cytochrome genes. This includes analysis of the cycFG operon which encodes cytochrome c₅₅₄ and a diheme cytochrome (CycG), plus the coxII and ctaD genes which encode two subunits of the cytochrome c oxidase complex.