Plant biology

Copper and Oxygen Converge

Science's STKE  26 Feb 2002:
Vol. 2002, Issue 121, pp. tw87
DOI: 10.1126/stke.2002.121.tw87

Plants must survive under many stressful environmental conditions. Quinn et al. studied the signaling pathway activated by hypoxic conditions in the algae Chlamydomonas reinhardtti. Hypoxia activates a set of genes also responsive to copper deficiency: Cpx1 (encoding coprogen oxidase), Cyc6 (encoding cytochrome c), and Crd1 (encoding a di-iron enzyme). Although the kinetics and sensitivity of the increases in gene expression in response to oxygen or copper deficiency were not identical, the stimulation of these genes had many similarities. Both required a copper response element (CRE) in the promoter of the target genes, although the hypoxia response required a second cis element of identical sequence to the CRE. Both responses required the trans-acting factor Crr1, and increases in the expression of three genes were blocked in crr1 mutants. Both oxygen- and copper-deficient gene activation were inhibited by the addition of nontoxic concentrations of mercury. Thus, for the regulation of certain genes, there is an apparent convergence of the pathways that sense and respond to changes in copper and oxygen concentrations. The common copper and oxygen regulatory pathway is not the only one activated in response to hypoxia, because the stimulation of expression of another gene regulated by oxygen deprivation, Hyd1, was not affected by mercury or in the crr1 mutants.

J. M. Quinn, M. Ericksson, J. L. Moseley, S. Merchant, Oxygen deficiency responsive gene expression in Chlamydomonas reinhardtti through a copper-sensing signal transduction pathway. Plant Physiol. 128, 463-471 (2002). [Abstract] [Full Text]