Immunological Identification of the Alternative Oxidase in Chlamydomonas Reinhardtii (Chlorophyta)1

Using a monoclonal antibody to the alternative oxidase from voodoo lily, we provide evidence that the green alga Chlamydomonas reinhardtii Dang, possesses a protein that is immunologically related to the higher plant alternative oxidase. Mitochondria were isolated from a cell wall‐less mutant strain (CW‐15), and the presence of cyanide‐resistant oxygen consumption was confirmed in these mitochondria. The voodoo lily antibody was used as a probe for immunoblotting of sodium dodecyl sulphate‐polyacrylamide gel electrophoresis gels of mitochondrial proteins of C. reinhardtii. The antibody reacted with a protein from C. reinhardtii with the same molecular mass (36 kDa) as the alternative oxidase from voodoo lily and tobacco mitochondria. These results suggest that cyanide‐resistant respiration in C. reinhardtii is mediated by a higher plant‐type alternative oxidase.