Role of mitochondrial inner membrane organizing system in protein biogenesis of the mitochondrial outer membrane.
Mitochondria contain two membranes, the outer membrane and the inner membrane with folded cristae. The mitochondrial inner membrane organizing system (MINOS) is a large protein complex required for maintaining inner membrane architecture. MINOS interacts with both preprotein transport machineries of the outer membrane, the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It is unknown, however, whether MINOS plays a role in the biogenesis of outer membrane proteins. We have dissected the interaction of MINOS with TOM and SAM and report that MINOS binds to both translocases independently. MINOS binds to the SAM complex via the conserved polypeptide transport-associated domain of Sam50. Mitochondria lacking mitofilin, the large core subunit of MINOS, are impaired in the biogenesis of β-barrel proteins of the outer membrane, whereas mutant mitochondria lacking any of the other five MINOS subunits import β-barrel proteins in a manner similar to wild-type mitochondria. We show that mitofilin is required at an early stage of β-barrel biogenesis that includes the initial translocation through the TOM complex. We conclude that MINOS interacts with TOM and SAM independently and that the core subunit mitofilin is involved in biogenesis of outer membrane β-barrel proteins.
Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany.
Maria
M
Bohnert
Lena-Sophie
LS
Wenz
Ralf M
RM
Zerbes
Susanne E
SE
Horvath
David A
DA
Stroud
Karina
K
von der Malsburg
Judith M
JM
Müller
Silke
S
Oeljeklaus
Inge
I
Perschil
Bettina
B
Warscheid
Agnieszka
A
Chacinska
Marten
M
Veenhuis
Ida J
IJ
van der Klei
Günther
G
Daum
Nils
N
Wiedemann
Thomas
T
Becker
Nikolaus
N
Pfanner
Martin
M
van der Laan
D017353:Gene Deletion; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000096:biosynthesis* / Q000737:chemistry; D046912:Multiprotein Complexes / Q000302:isolation & purification / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000302:isolation & purification / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000737:chemistry
D024101:Mitochondrial Proteins; D046912:Multiprotein Complexes; D010455:Peptides; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins