Pam17 is required for architecture and translocation activity of the mitochondrial protein import motor.
Import of mitochondrial matrix proteins involves the general translocase of the outer membrane and the presequence translocase of the inner membrane. The presequence translocase-associated motor (PAM) drives the completion of preprotein translocation into the matrix. Five subunits of PAM are known: the preprotein-binding matrix heat shock protein 70 (mtHsp70), the nucleotide exchange factor Mge1, Tim44 that directs mtHsp70 to the inner membrane, and the membrane-bound complex of Pam16-Pam18 that regulates the ATPase activity of mtHsp70. We have identified a sixth motor subunit. Pam17 (encoded by the open reading frame YKR065c) is anchored in the inner membrane and exposed to the matrix. Mitochondria lacking Pam17 are selectively impaired in the import of matrix proteins and the generation of an import-driving activity of PAM. Pam17 is required for formation of a stable complex between the cochaperones Pam16 and Pam18 and promotes the association of Pam16-Pam18 with the presequence translocase. Our findings suggest that Pam17 is required for the correct organization of the Pam16-Pam18 complex and thus contributes to regulation of mtHsp70 activity at the inner membrane translocation site.
van der Laan
Martin
M
Institut für Biochemie und Molekularbiologie, Universität Freiburg, Germany.
Chacinska
Agnieszka
A
Lind
Maria
M
Perschil
Inge
I
Sickmann
Albert
A
Meyer
Helmut E
HE
Guiard
Bernard
B
Meisinger
Chris
C
Pfanner
Nikolaus
N
Rehling
Peter
P
D000595:Amino Acid Sequence; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D020409:Molecular Motor Proteins; C480348:PAM18 J protein, S cerevisiae; C484526:Pam16 protein, S cerevisiae; C503873:Pam17 protein, S cerevisiae; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae