Prof. Sabeeha Merchant, UCLA

Trace metal economy in Chlamydomonas

School Colloquium

Inorganic trace elements can limit the abundance of photosynthetic organisms because of their role as cofactors in enzymes. In Chlamydomonas cultures placed in a situation of poor copper nutrition, copper is preferentially allocated to cytochrome oxidase over ferroxidase and plastocyanin. In a pathway controlled by a copper-sensing transcription factor, plastocyanin, functionally replaced by cytochrome c6, is degraded and its copper cofactor is recycled for continued synthesis of cytochrome oxidase, an essential enzyme in respiration. RNA-seq analysis of the Chlamydomonas transcriptome in batch culture of copper-deficient cells identifies a candidate protease for plastocyanin degradation. The co-occurrence of genetic information for plastocyanin as well as functionally-equivalent cytochrome c6 in algal and cyanobacterial genomes suggests a role for plastocyanin in copper sequestration, which may provide a competitive advantage in copper-deplete environments.

For more information contact Prof. Christoph Fahrni (404-385-1164).