Mitochondrial DNA of Chlamydomonas reinhardtii: The gene for apocytochrome b and the complete functional map of the 15.8 kb DNA

Abstract

We have sequenced the termini of the mitochondrial genome of Chlamydomonas reinhardtii and now present the DNA sequence of the gene for apocytochrome b. This gene is the thirteenth gene of the linear 15.8 kb DNA and appears to be the last one of the mt genome. The deduced protein sequence of 381 amino acid residues shows 56%, 48.6% and 48% identity with the apocytochrome b proteins of maize, Drosophila yakuba and mouse, respectively. RNA analysis reveals a transcript of about 1250 nucleotides. It is now possible to present the complete protein-coding capacity, the pattern of codon utilization for all eight protein genes, and the complete functional map of the mitochondrial 15.8 kb DNA of C. reinhardtii. One surprising feature is the absence of mitochondrial genes for ATPase and subunits II and III of cytochrome oxidase. No more than three tRNA genes appear to be present on the 15.8 kb mitochondrial DNA.

Phylogeny and Molecular Evolution of the Green Algae

“…The most diminutive mtDNAs from the Viridiplantae are currently found in the Chlorophyceae. For example, the mtDNAs of Polytomella species range from 13-16 kb (Smith et al, 2010a) and that of C. reinhardtii varies from 16-19 kb (depending on the presence of optional introns) Michaelis et al, 1990;Vahrenholz et al, 1993). Though small, chlorophycean mtDNAs can be quite bloated; both the D. salina and V. carteri mtDNAs are ~60% noncoding (Smith et al, 2010b).…”

Ferritin is required for rapid remodeling of the photosynthetic apparatus and minimizes photo‐oxidative stress in response to iron availability in Chlamydomonas reinhardtii

“…Its ability to grow photo-heterotrophically or photo-autotrophically, the possibility of transforming all three genomes (Rochaix, 1995), all of which are sequenced (Maul et al, 2002;Merchant et al, 2007;Michaelis et al, 1990), and numerous molecular tools such as RNAi (Rohr et al, 2004) as well as proteomic approaches (Hippler et al, 2001) make Chlamydomonas a versatile model organism. Numerous studies have been published with respect to its iron homeostasis and consequences of iron deficiency (Allen et al, 2007;La Fontaine et al, 2002;Moseley et al, 2002;Naumann et al, 2005Naumann et al, , 2007, showing that Chlamydomonas reacts in a fine-tuned manner to changing iron availability.…”

Unusual Location of a Mitochondrial Gene

“…This compact and highly diverged mitochondrial genome has been entirely sequenced (5). Several genes that encode essential components of oxidative phosphorylation that are usually found in mitochondrial genomes are absent in this mtDNA: nad3 and nad4L (encoding subunits 3 and 4L of NADH-ubiquinol oxidoreductase), cox2 and cox3 (encoding COX II and COX III), and atp6 and atp8 (encoding subunits a and A6L of the F 0 portion of ATP synthase).…”