Novel class of nuclear genes involved in both mRNA splicing and protein synthesis in Saccharomyces cerevisiae mitochondria.
We have cloned three distinct nuclear genes, NAM1, NAM7, and NAM8, which alleviate mitochondrial intron mutations of the cytochrome b and COXI (subunit I of cytochrome oxidase) genes when present on multicopy plasmids. These nuclear genes show no sequence homology to each other and are localized on different chromosomes: NAM1 on chromosome IV, NAM7 on chromosome XIII and NAM8 on chromosome VIII. Sequence analysis of the NAM1 gene shows that it encodes a protein of 440 amino acids with a typical presequence that would target the protein to the mitochondrial matrix. Inactivation of the NAM1 gene by gene transplacement leads to a dramatic reduction of the overall synthesis of mitochondrial protein, and a complete absence of the COXI protein which is the result of a specific block in COXI pre-mRNA splicing. The possible mechanisms by which the NAM1 gene product may function are discussed.
Asher
E B
EB
Centre de Génétique Moléculaire du C.N.R.S., Laboratoire propre associé à l'Université P. et M. Curie, Gif-sur-Yvette, France.
Groudinsky
O
O
Dujardin
G
G
Altamura
N
N
Kermorgant
M
M
Slonimski
P P
PP
D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D005800:Genes, Fungal; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013489:Suppression, Genetic; D014158:Transcription, Genetic
D004271:DNA, Fungal; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger