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Metal ion regulated gene expression: use of a plastocyanin‐less mutant of Chlamydomonas reinhardtii to study the Cu(II)‐dependent expression of cytochrome c‐552.
Author(s) -
Merchant S.,
Bogorad L.
Publication year - 1987
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1987.tb02540.x
Subject(s) - plastocyanin , chlamydomonas reinhardtii , biology , mutant , chlamydomonas , cytochrome , microbiology and biotechnology , gene expression , biochemistry , gene , enzyme , photosystem i , chloroplast
Ac‐208, a plastocyanin‐deficient strain of Chlamydomonas reinhardtii, lacks the mRNA for pre‐apoplastocyanin although Southern analyses indicate no gross deletion in the single gene for pre‐apoplastocyanin. The alternative electron carrier, cytochrome c‐552, is expressed only in Cu(II)‐deficient cells of the mutant. Thus, the mutant strain can grow photoautotrophically in Cu(II)‐deficient but not in Cu(II)‐sufficient medium. This indicates that the absence of plastocyanin is the only defect (with respect to photosynthesis) in ac‐208. Phenotypic revertants of ac‐208 are capable of photoautotrophic growth by virtue of constitutive [with respect to Cu(II)] synthesis of cytochrome c‐552. The revertant phenotype is attributed to a decreased internal concentration of Cu(II). This indicates that the Cu(II)‐dependent expression of cytochrome c‐552 synthesis is affected directly by the concentration of Cu(II) rather than indirectly by the level of plastocyanin in the cell.