%0 Journal Article
%T Cadmium triggers an integrated reprogramming of the metabolism of Synechocystis PCC6803, under the control of the Slr1738 regulator
%A Laetitia Houot
%A Martin Floutier
%A Benoit Marteyn
%A Magali Michaut
%A Antoine Picciocchi
%A Pierre Legrain
%A Jean-Christophe Aude
%A Corinne Cassier-Chauvat
%A Franck Chauvat
%J BMC Genomics
%D 2007
%I BioMed Central
%R 10.1186/1471-2164-8-350
%X We found that cells respond to the Cd stress in a two main temporal phases process. In the "early" phase cells mainly limit Cd entry through the negative and positive regulation of numerous genes operating in metal uptake and export, respectively. As time proceeds, the number of responsive genes increases. In this "massive" phase, Cd downregulates most genes operating in (i) photosynthesis (PS) that normally provides ATP and NADPH; (ii) assimilation of carbon, nitrogen and sulfur that requires ATP and NAD(P)H; and (iii) translation machinery, a major consumer of ATP and nutrients. Simultaneously, many genes are upregulated, such as those involved in Fe acquisition, stress tolerance, and protein degradation (crucial to nutrients recycling). The most striking common effect of Cd and H2O2 is the disturbance of both light tolerance and Fe homeostasis, which appeared to be interdependent. Our results indicate that cells challenged with H2O2 or Cd use different strategies for the same purpose of supplying Fe atoms to Fe-requiring metalloenzymes and the SUF machinery, which synthesizes or repairs Fe-S centers. Cd-stressed cells preferentially breakdown their Fe-rich PS machinery, whereas H2O2-challenged cells preferentially accelerate the intake of Fe atoms from the medium.We view the responses to Cd as an integrated "Yin Yang" reprogramming of the whole metabolism, we found to be controlled by the Slr1738 regulator. As the Yin process, the ATP- and nutrients-sparing downregulation of anabolism limits the poisoning incorporation of Cd into metalloenzymes. As the compensatory Yang process, the PS breakdown liberates nutrient assimilates for the synthesis of Cd-tolerance proteins, among which we found the Slr0946 arsenate reductase enzyme.Photosynthetic organisms that support much of the life on Earth, in using solar energy to renew the oxygenic atmosphere and make up organic assimilates essential to the food chain [1,2] are frequently challenged with toxic reactive oxygen s
%U http://www.biomedcentral.com/1471-2164/8/350