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Copper economy in Chlamydomonas: prioritized allocation and reallocation of copper to respiration vs. photosynthesis.

ABSTRACT: Inorganic elements, although required only in trace amounts, permit life and primary productivity because of their functions in catalysis. Every organism has a minimal requirement of each metal based on the intracellular abundance of proteins that use inorganic cofactors, but elemental sparing mechanisms can reduce this quota. A well-studied copper-sparing mechanism that operates in microalgae faced with copper deficiency is the replacement of the abundant copper protein plastocyanin with a heme-containing substitute, cytochrome (Cyt) c6. This switch, which is dependent on a copper-sensing transcription factor, copper response regulator 1 (CRR1), dramatically reduces the copper quota. We show here that in a situation of marginal copper availability, copper is preferentially allocated from plastocyanin, whose function is dispensable, to other more critical copper-dependent enzymes like Cyt oxidase and a ferroxidase. In the absence of an extracellular source, copper allocation to Cyt oxidase includes CRR1-dependent proteolysis of plastocyanin and quantitative recycling of the copper cofactor from plastocyanin to Cyt oxidase. Transcriptome profiling identifies a gene encoding a Zn-metalloprotease, as a candidate effecting copper recycling. One reason for the retention of genes encoding both plastocyanin and Cyt c6 in algal and cyanobacterial genomes might be because plastocyanin provides a competitive advantage in copper-depleted environments as a ready source of copper.

SUBMITTER: Kropat J

PROVIDER: S-EPMC4352834 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Copper economy in Chlamydomonas: prioritized allocation and reallocation of copper to respiration vs. photosynthesis.

Kropat Janette J Gallaher Sean D SD Urzica Eugen I EI Nakamoto Stacie S SS Strenkert Daniela D Tottey Stephen S Mason Andrew Z AZ Merchant Sabeeha S SS

Proceedings of the National Academy of Sciences of the United States of America 20150202 9

Inorganic elements, although required only in trace amounts, permit life and primary productivity because of their functions in catalysis. Every organism has a minimal requirement of each metal based on the intracellular abundance of proteins that use inorganic cofactors, but elemental sparing mechanisms can reduce this quota. A well-studied copper-sparing mechanism that operates in microalgae faced with copper deficiency is the replacement of the abundant copper protein plastocyanin with a heme ...[more]

PMID: 25646490

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Dataset Information

Copper economy in Chlamydomonas: prioritized allocation and reallocation of copper to respiration vs. photosynthesis.

Publications

Copper economy in Chlamydomonas: prioritized allocation and reallocation of copper to respiration vs. photosynthesis.

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