Witnessing the evolution of transcription in mitochondria: the mitochondrial genome of the primitive brown alga Pylaiella littoralis (L.) Kjellm. Encodes a T7-like RNA polymerase.
A region of the mitochondrial genome of the primitive brown alga Pylaiella littoralis containing a plasmid-like insert which contains a transcribed T7-phage-type RNA polymerase gene is described. This is a first report of a phage-type RNA polymerase gene integrated in a mitochondrial genome. As the mitochondrial genome of this alga also contains sigma-70 proteobacterial promoter regions, i.e. traces of the ancestral alpha2betabeta'sigma-70 proteobacterial RNA polymerase, this genome witnesses two types of RNA polymerases. As such the mitochondrial genome of P. littoralis represents a unique stage in the evolution of transcription in mitochondria, which contrasts with that of the primitive protist Reclinomonas americana, which still retains the ancestral alpha2betabeta'sigma-70 proteobacterial RNA polymerase genes, and with animals, land plants and fungi, which use phage-type polymerases.
Rousvoal
S
S
Station Biologique de Roscoff, CNRS (UPR 9042), UPMC B.P. 74, Roscoff, Cedex, 29682, France.
Oudot
M
M
Fontaine
J
J
Kloareg
B
B
Goër
S L
SL
D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004272:DNA, Mitochondrial / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry*; D056890:Eukaryota / Q000201:enzymology*; D019143:Evolution, Molecular; D008928:Mitochondria / Q000235:genetics*; D008957:Models, Genetic; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000235:genetics
D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D012321:DNA-Directed RNA Polymerases