|MARTY, NAOMI - University Of Guelph|
|HWANG, YEEN - University Of Guelph|
|ZHANG, DAIYUAN - University Of North Texas|
|MULLEN, ROBERT - University Of Guelph|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2010
Publication Date: 7/31/2010
Citation: Marty, N.J., Hwang, Y.T., Zhang, D., Dyer, J.M., and Mullen, R.T. (2010). Distinct Pathways Mediate the Sorting of Tail-anchored Mitochondrial Outer Membrane Proteins. Joint Meeting of the American Society of Plant Biologists and the Canadian Society of Plant Physiologists, July 31 - August 4, 2010, Montreal, Canada.
Technical Abstract: Little is known about the biogenesis of tail-anchored (TA) proteins localized to the mitochondrial outer membrane in plant cells. To address this issue, we screened all of the (>600) known and predicted TA proteins in Arabidopsis thaliana for those annotated, based on Gene Ontology, to possess mitochondrial-related function(s) and/or contain a C-terminal sequence resembling the targeting signal motif characterized previously for mitochondrial isoforms of the TA protein cytochrome b5 (Cb5). Surprisingly, only two of the ~35 TA proteins functionally annotated as mitochondrial possessed a Cb5-like targeting signal. Using tobacco BY-2 cells as a model in vivo targeting system we confirmed the mitochondrial localization and TA topology for several novel members of each group of proteins, and subsequent mutagenic analyses revealed that their C termini, while distinctly different at the primary sequence level, were both necessary and sufficient for mitochondrial targeting. We also employed split-YFP assays to show that while both groups of TA proteins interact with certain components of the mitochondrial outer membrane translocase (TOM), only a few TA proteins interact also with the sorting and assembly machinery (SAM). Collectively, these results in combination with other findings suggest that plant mitochondrial TA proteins, like TA proteins that are localized to other organelles (e.g., chloroplasts and ER), rely on several different and possibly parallel sorting pathways.