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Wilfrid Laurier University Leaf
December 1, 2015

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Biology Research Seminar

Oct 15/15

Date: Oct 15/15
Time: 14:30 - 15:30
Location: N1044
Cost: Free

Integrative Biology Session Thursday Oct 15, 2015
Room: N1044
Time: 2:30 - 3:30pm

Title: Evolution of essential proteins in the chloroplast outer envelope membrane.

The chloroplast is an organelle unique to photosynthetic eukaryotes and essential for their viability. It originated from an ancestral cyanobacterium via endosymbiosis and is still surrounded by a double-membrane envelope, although a peptidoglycan layer has been lost in most lineages. The successful conversion of the endosymbiont to the organelle requires transfer of many genes from its genome to the host nucleus. This process depended on the establishment of molecular machinery that mediates import of nuclear-encoded proteins across the double-membrane envelope. Among components of such a machine is a member of the Omp85 family called Toc75, which forms a protein conducting channel at the outer envelope membrane. The Omp85 family includes BamA in Gram-negative bacteria and Sam50 in mitochondria, both of which play essential roles in cell viability by catalyzing folding and integration of beta-barrel proteins in the outer membranes, but not in protein import. Besides Toc75, the chloroplast in green lineages contains another Omp85 called OEP80. Phylogenetic studies have demonstrated that the two chloroplast Omp85 diverged early in the evolution of chloroplasts. Genetic studies have demonstrated that both Toc75 and OEP80 are essential for plant viability from the embryonic stage although the exact function of OEP80 remains elusive. We hypothesize that the duplication of the Omp85 gene that gave rise to Toc75 and OEP80 must have been a critical step in chloroplast evolution, and are determined to elucidate its molecular details. This talk will include our findings about their targeting mechanisms and progress towards defining the function of OEP80. Supported by the Division of Molecular and Cellular Biosciences at the US National Science Foundation 1050602.

All are welcome.


Contact: Jennifer Baltzer
Phone: 519-884-0710 x4188

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