Mdj2p, a novel DnaJ homolog in the mitochondrial inner membrane of the yeast Saccharomyces cerevisiae.
Members of the heat shock protein 70 (Hsp70) family mediate import, folding, assembly and degradation of proteins in mitochondria. The function of Hsp70 proteins is dependent on their interaction with cofactors, including members of the DnaJ protein family. The mitochondrial DnaJ homolog, Mdj1p, has been shown to cooperate with the major mitochondrial Hsp70, mt-Hsp70. We describe the identification of a second mitochondrial DnaJ homolog, Mdj2p, in the yeast Saccharomyces cerevisiae. The protein possesses an N-terminal transmembrane domain that anchors it in the mitochondrial inner membrane. The C-terminal J-domain shares 30% amino acid identity with the J-domain of Escherichia coli DnaJ and is exposed to the mitochondrial matrix. Mdj2p carries a putative internal mitochondrial targeting signal and is imported into mitochondria in a membrane potential-dependent manner. Deletion of the MDJ2 gene did not result in a detectable growth defect. Double mutants of mdj1 and mdj2 showed severe growth defects at elevated temperature, indicating a distinct overlap of the functions of Mdj1p and Mdj2p.
Westermann
B
B
Institut für Physiologische Chemie der Universität München, Goethestrasse 33, München, D-80336, Germany.
Neupert
W
W
D000595:Amino Acid Sequence; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000737:chemistry*; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000737:chemistry*; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry*; D008928:Mitochondria / Q000737:chemistry*; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D015398:Signal Transduction
C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C087041:MDJ1 protein, S cerevisiae; C108930:MDJ2 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins