RPM2, independently of its mitochondrial RNase P function, suppresses an ISP42 mutant defective in mitochondrial import and is essential for normal growth.
RPM2 is identified here as a high-copy suppressor of isp42-3, a temperature-sensitive mutant allele of the mitochondrial protein import channel component, Isp42p. RPM2 already has an established role as a protein component of yeast mitochondrial RNase P, a ribonucleoprotein enzyme required for the 5' processing of mitochondrial precursor tRNAs. A relationship between mitochondrial tRNA processing and protein import is not readily apparent, and, indeed, the two functions can be separated. Truncation mutants lacking detectable RNase P activity still suppress the isp42-3 growth defect. Moreover, RPM2 is required for normal fermentative yeast growth, even though mitochondrial RNase P activity is not. The portion of RPM2 required for normal growth and suppression of isp42-3 is the same. We conclude that RPM2 is a multifunctional gene. We find Rpm2p to be a soluble protein of the mitochondrial matrix and discuss models to explain its suppression of isp42-3.
Kassenbrock
C K
CK
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, USA.
Gao
G J
GJ
Groom
K R
KR
Sulo
P
P
Douglas
M G
MG
Martin
N C
NC
D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002451:Cell Compartmentation; D004252:DNA Mutational Analysis; D004722:Endoribonucleases / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D005800:Genes, Fungal / Q000235:genetics; D005804:Genes, Lethal; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D012313:RNA / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016337:RNA, Catalytic / Q000378:metabolism; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000378:metabolism; D043262:Ribonuclease P; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic
D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D016337:RNA, Catalytic; D000077278:RNA, Mitochondrial; D029701:Saccharomyces cerevisiae Proteins; C066555:Tom40 protein, S cerevisiae; D012313:RNA; D012343:RNA, Transfer; D004722:Endoribonucleases; D043262:Ribonuclease P