Heavy metal-activated synthesis of peptides in Chlamydomonas reinhardtii

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Plant Physiology; (United States)

DOI:https://doi.org/10.1104/pp.98.1.127· OSTI ID:7044721

Howe, G; Merchant, S ^[1]

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1. Univ. of California, Los Angeles (United States)

In this study, the authors have addressed the capacity of the green alga Chlamydomonas reinhardtii to produce metal-binding peptides in response to stress induced by the heavy metals Cd{sup 2+}, Hg{sup 2+}, and Ag{sup +}. Cells cultured in the presence of sublethal concentrations of Cd{sup 2+} synthesized and accumulated oligopeptides consisting solely of glutamic acid, cysteine, and glycine in an average ratio of 3:3:1. Cadmium-induced peptides were isolated in their native form as higher molecular weight peptide-metal complexes with an apparent molecular weight of approximately 6.5 {times} 10{sup 3}. The isolated complex bound cadmium (as evidenced by absorption spectroscopy) and sequestered (with a stoichiometry of 0.7 moles of cadmium per mole of cysteine) up to 70% of the total cadmium found in extracts of cadmium-treated cells. In Hg{sup 2+}-treated cells, the principal thiol-containing compound induced by Hg{sup 2+} ion was glutathione. It is possible that glutathione functions in plant cells (as it does in animal cells) to detoxify heavy metals. Cells treated with Ag{sup +} ions also synthesized a sulfur-containing component with a charge to mass ratio similar to Cd{sup 2+}-induced peptides. But, in contrast to the results obtained using Cd{sup 2+} as an inducer, these molecules did not accumulate to significant levels in Ag{sup +}-treated cells. The presence of physiological concentrations of Cu{sup 2+} in the growth medium blocked the synthesis of the Ag{sup +}-inducible component(s) and rendered cells resistant to the toxic effects of Ag{sup +}, suggesting competition between Cu{sup 2+} and Ag{sup +} ions, possibly at the level of metal uptake.

• OSTI ID: 7044721
• Journal Information: Plant Physiology; (United States), Vol. 98:1; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CHLAMYDOMONAS
PHYSIOLOGY
METALS
TOXICITY
PEPTIDES
BIOSYNTHESIS
AMINO ACIDS
CADMIUM COMPOUNDS
CATIONS
COPPER COMPOUNDS
GLUTATHIONE
MERCURY COMPOUNDS
PLANT CELLS
SILVER COMPOUNDS
UPTAKE
ALGAE
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHLOROPHYCOTA
DRUGS
ELEMENTS
IONS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
POLYPEPTIDES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
UNICELLULAR ALGAE
560300* - Chemicals Metabolism & Toxicology