The mitochondrial porin, VDAC, has retained the ability to be assembled in the bacterial outer membrane.
Beta-barrel proteins are present in the outer membranes (OMs) of Gram-negative bacteria, mitochondria, and chloroplasts. Their assembly requires a machinery of which the central component, called Omp85 (BamA) in bacteria and Tob55 (Sam50) in mitochondria, is evolutionarily conserved. An open question is whether the signals in beta-barrel OM proteins required for assembly via this multicomponent machinery are also conserved. To address this question, we have expressed in Escherichia coli the mitochondrial porin voltage-dependent anion channel (VDAC) from Neurospora crassa fused to a bacterial signal sequence for transport across the bacterial inner membrane. The protein was assembled in the bacterial OM where it formed pores. Assembly of VDAC was dependent on its beta-signal, which is required for assembly in the mitochondrial OM, and on the bacterial Omp85 assembly machinery. These results demonstrate that the basic mechanism of beta-barrel assembly in the OMs of bacteria and mitochondria is conserved.
Walther
Dirk M
DM
Interfaculty Institute for Biochemistry, University of Tübingen, Tübingen, Germany.
Bos
Martine P
MP
Rapaport
Doron
D
Tommassen
Jan
J
D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D009492:Neurospora crassa / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D050994:Voltage-Dependent Anion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D005656:Fungal Proteins; D011994:Recombinant Proteins; D050994:Voltage-Dependent Anion Channels