The Neurospora crassa TOB complex: analysis of the topology and function of Tob38 and Tob37

The TOB or SAM complex is responsible for assembling several proteins into the mitochondrial outer membrane, including all β-barrel proteins. We have identified several forms of the complex in Neurospora crassa. One form contains Tob55, Tob38, and Tob37; another contains these three subunits plus th...

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Bibliographic Details
Published in:PloS one 2011-09, Vol.6 (9), p.e25650-e25650
Main Authors: Lackey, Sebastian W K, Wideman, Jeremy G, Kennedy, Erin K, Go, Nancy E, Nargang, Frank E
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Analysis
Animals
Biology
Biosynthesis
Cell Membrane - metabolism
Cell Nucleus - metabolism
Fungal Proteins - chemistry
Fungal Proteins - genetics
Fungal Proteins - metabolism
Gene Knockout Techniques
Humans
Hydrophobic and Hydrophilic Interactions
Hydrophobicity
Mammals
Mitochondria
Mitochondria - metabolism
Molecular Sequence Data
Morphology
Neurospora
Neurospora crassa
Neurospora crassa - cytology
Neurospora crassa - metabolism
Protein Structure, Tertiary
Proteins
Saccharomyces cerevisiae
Topology
Viability
Yeast
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Summary:The TOB or SAM complex is responsible for assembling several proteins into the mitochondrial outer membrane, including all β-barrel proteins. We have identified several forms of the complex in Neurospora crassa. One form contains Tob55, Tob38, and Tob37; another contains these three subunits plus the Mdm10 protein; while additional complexes contain only Tob55. As previously shown for Tob55, both Tob37 and Tob38 are essential for viability of the organism. Mitochondria deficient in Tob37 or Tob38 have reduced ability to assemble β-barrel proteins. The function of two hydrophobic domains in the C-terminal region of the Tob37 protein was investigated. Mutant Tob37 proteins lacking either or both of these regions are able to restore viability to cells lacking the protein. One of the domains was found to anchor the protein to the outer mitochondrial membrane but was not necessary for targeting or association of the protein with mitochondria. Examination of the import properties of mitochondria containing Tob37 with deletions of the hydrophobic domains reveals that the topology of Tob37 may be important for interactions between specific classes of β-barrel precursors and the TOB complex.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0025650