The NAM8 gene in Saccharomyces cerevisiae encodes a protein with putative RNA binding motifs and acts as a suppressor of mitochondrial splicing deficiencies when overexpressed.
We have characterized the nuclear gene NAM8 in Saccharomyces cerevisiae. It acts as a suppressor of mitochondrial splicing deficiencies when present on a multicopy plasmid. The suppressed mutations affect RNA folding and are located in both group I and group II introns. The gene is weakly transcribed in wild-type strains, its overexpression is a prerequisite for the suppressor action. Inactivation of the NAM8 gene does not affect cell viability, mitochondrial function or mitochondrial genome stability. The NAM8 gene encodes a protein of 523 amino acids which includes two conserved (RNP) motifs common to RNA-binding proteins from widely different organisms. This homology with RNA-binding proteins, together with the intronic location of the suppressed mitochondrial mutations, suggests that the NAM8 protein could be a non-essential component of the mitochondrial splicing machinery and, when present in increased amounts, it could convert a deficient intron RNA folding pattern into a productive one.
Ekwall
K
K
Centre de Génétique Moléculaire, Laboratoire propre du C.N.R.S. associé à l'Université P. et M. Curie, Gif-sur-Yvette, France.
Kermorgant
M
M
Dujardin
G
G
Groudinsky
O
O
Slonimski
P P
PP
D000595:Amino Acid Sequence; D001483:Base Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005784:Gene Amplification; D005800:Genes, Fungal; D016153:Genes, Suppressor; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids; D012326:RNA Splicing / Q000235:genetics*; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic
D005656:Fungal Proteins; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C075023:NAM8 protein, S cerevisiae