CeBiTec Colloquium


Monday, June 28th 2010, 17 c.t.


G2-104, CeBiTec Building


Prof. Dr. Claire Remacle

Department of Life Sciences, Institute of Botany, University of Liege, Belgium


Mitochondrial complex I in Chlamydomonas reinhardtii: a forward genetic screen allows to isolate mutants deficient for the activity and assembly of the assembly

  With more than 40 subunits, one FMN molecule and 8 Fe-S clusters, mitochondrial complex I is the largest multimeric enzyme of the respiratory chain. Using Chlamydomonas reinhardtii as an experimental system to screen for complex I defects, we isolated amc1 to amc7 nuclear mutants (for assembly of mitochondrial complex I) that result in no or reduced complex I activity. BN-PAGE and immunoblot analyses reveal that amc3 and amc4 accumulate reduced levels of whole complex I (950 kDa) while all other amc mutants fail to accumulate a mature complex. In amc1, amc2, amc5, amc6 and amc7, the detection of a subcomplex of about 700 kDa that retains NADH dehydrogenase activity indicates an arrest in the assembly process. All amc mutants also showed an increase in the electron transfer through complexes II and III. Genetic analyses established that amc5 and amc7 are alleles of the same locus while amc1, amc2, amc3, amc4 and amc6 define distinct complementation groups. The locus corresponding to amc5 and amc7 alleles was cloned and shown to correspond to the NUOB10 gene that encodes PDSW, a subunit of the membrane arm of complex I. This is the first report of a forward genetic screening yielding the isolation of complex I mutants.

Prof. Dr. Olaf Kruse