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Functional characterization of an N-terminally-truncated mitochondrial porin expressed in Neurospora crassa.

Authors
  • Shuvo, Sabbir R1, 1
  • Kovaltchouk, Uliana1, 1
  • Zubaer, Abdullah1, 1
  • Kumar, Ayush1, 1
  • Summers, William A T1, 1
  • Donald, Lynda J1, 1
  • Hausner, Georg1, 1
  • Court, Deborah A1, 1
  • 1 Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. , (Canada)
Type
Published Article
Journal
Canadian Journal of Microbiology
Publisher
Canadian Science Publishing
Publication Date
Aug 01, 2017
Volume
63
Issue
8
Pages
730–738
Identifiers
DOI: 10.1139/cjm-2016-0764
PMID: 28414919
Source
Medline
Keywords
License
Unknown

Abstract

Mitochondrial porin, which forms voltage-dependent anion-selective channels (VDAC) in the outer membrane, can be folded into a 19-β-stranded barrel. The N terminus of the protein is external to the barrel and contains α-helical structure. Targeted modifications of the N-terminal region have been assessed in artificial membranes, leading to different models for gating in vitro. However, the in vivo requirements for gating and the N-terminal segment of porin are less well-understood. Using Neurospora crassa porin as a model, the effects of a partial deletion of the N-terminal segment were investigated. The protein, ΔN2-12porin, is assembled into the outer membrane, albeit at lower levels than the wild-type protein. The resulting strain displays electron transport chain deficiencies, concomitant expression of alternative oxidase, and decreased growth rates. Nonetheless, its mitochondrial genome does not contain any significant mutations. Most of the genes that are expressed in high levels in porin-less N. crassa are expressed at levels similar to that of wild type or are slightly increased in ΔN2-12porin strains. Thus, although the N-terminal segment of VDAC is required for complete function in vivo, low levels of a protein lacking part of the N terminus are able to rescue some of the defects associated with the absence of porin.

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