From copper economy to copper overload in the green lineage

Title:

From copper economy to copper overload in the green lineage 

Schedule:

Date: 14 July 2023 (Friday)

Time: 10:30 am - 11:30 am (HKT)

Venue: 

Lecture theatre P1, Chong Yuet Ming Chemistry Building

Speaker:

Prof. Sabeeha Merchant 

Quantitative Biosciences Institute

University of California, Berkeley 

Abstract: 

When faced with Cu deficiency, Chlamydomonas up-regulates assimilatory copper transporters (CTR proteins) and reduces its inventory of copper-containing proteins by replacing them with copper-independent catalysts. In situations of Cu starvation or sustained deficiency, Chlamydomonas can remove Cu from an abundant cuproprotein, plastocyanin in photosynthesis, and reuse it in a different - more critical for life – protein, cytochrome oxidase. This mechanism is driven by signaling through a transcription factor, CRR1, whose activity is dependent on intracellular Cu sensing. CRR1 binds to copper response elements associated with > 60 genes in the Chlamydomonas copper regulon to activate their transcription in Cu-deficient cells. At the other end of the nutritional spectrum, Chlamydomonas cells overload with Cu when faced with Zn-deficiency. Cu overload depends on 1) CRR1 and the CTR transporters, presumably for promoting assimilation, and 2) S nutrition and cysteine accumulation, presumably for chelating Cu(I). The resulting complexes are stored in an acidic lysosome related organelle from where Cu(I) is preferentially mobilized for cuproprotein biosynthesis over extra-cellular Cu when homeostasis is restored.   

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