2006 Ohio Student Research Forum

Abstract

Contribution to the study of complex I assembly in Chlamydomonas reinhardtii
Omar Ahmed
Ohio State University
Department of Biological Sciences
Mentor: Dr. Patrice Hamel

Many mitochondrial dysfunctions in humans are due to a deficiency in complex I, a multimeric respiratory complex in the mitochondrial inner membrane. The investigation of complex I deficiencies is difficult in humans because of the strict regulations on human material. In this study we propose to explore complex I assembly in a simpler unicellular organism, Chlamydomonas reinhardtii, a green alga. Our goals are 1) Engineer a selectable marker for transformation of the mitochondrial genome by using the ARG9 gene, which encodes acetylornithine aminotransferase, an enzyme involved in arginine biosynthesis and localized in the mitochondria. The objective is to reconstruct human-disease associated mutations in Chlamydomonas in order to study their impact on the activity/assembly of complex I and 2) Isolate nuclear mutants which are deficient for complex I assembly. This will be achieved by insertional mutagenesis via transformation of C. reinhardtii by use of the hph gene, an antibiotic (hygromycin B) resistance marker. Candidate complex I mutants will be screened for the slow growth phenotype in the dark and in the light and further analyzed by biochemistry to confirm loss of complex I assembly. Novel factors that control the assembly process of complex I are expected to be discovered through this mutagenesis screen.