title: cDNA and deduced amino acid sequences of cytochrome c from Chlamydomonas reinhardtii: unexpected functional and phylogenetic implications.
abstract: We have isolated complementary DNA (cDNA) clones for apocytochrome c from the green alga Chlamydomonas reinhardtii and shown that they are encoded by a single nuclear gene termed cyc. Cyc mRNA levels are found to depend primarily on the presence of acetate as a reduced carbon source in the culture medium. The deduced amino acid sequence shows that, apart from the probable removal of the initiating methionine, C. reinhardtii apocytochrome c is synthesized in its mature form. Its structure is generally similar to that of cytochromes c from higher plants. Several punctual deviations from the general pattern of cytochrome c sequences that is found in other organisms have interesting structural and functional implications. These include, in particular, valines 19 and 39, asparagine 78, and alanine 83. A phylogenetic tree was constructed by the matrix method from cytochrome c data for a representative range of species. The results suggest that C. reinhardtii diverged from higher plants approximately 700-750 million years ago; they also are not easy to reconcile with the current attribution of Chlamydomonas reinhardtii and Enteromorpha intestinalis to a unique phylum, because these two species probably diverged from one another at about the same time as they diverged from the line leading to higher plants.
authors.affiliation: Department of Molecular Biology, University of Geneva, Switzerland.
authors.forename: B B
authors.initials: BB
authors.lastname: Amati
authors.forename: M
authors.initials: M
authors.lastname: Goldschmidt-Clermont
authors.forename: C J
authors.initials: CJ
authors.lastname: Wallace
authors.forename: J D
authors.initials: JD
authors.lastname: Rochaix
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002696:Chlamydomonas / Q000201:enzymology / Q000235:genetics*; D003574:Cytochrome c Group / Q000235:genetics*; D004247:DNA / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012689:Sequence Homology, Nucleic Acid
chemical_list: D003574:Cytochrome c Group; D004247:DNA