Sucrose synthase and RuBisCo expression is similarly regulated by the nitrogen source in the nitrogen-fixing cyanobacterium Anabaena sp. |
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Authors: | Leonardo Curatti Laura Giarrocco Graciela L Salerno |
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Institution: | (1) Centro de Investigaciones Biológicas, Fundación para Investigaciones Biológicas Aplicadas (FIBA), CC 1348, 7600 Mar del Plata, Argentina;(2) Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102, USA |
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Abstract: | In higher plants and cyanobacteria, sucrose (Suc) metabolism is carried out by a similar set of enzymes. The function and
regulation of Suc metabolism in cyanobacteria has begun to be elucidated. In strains of Anabaena sp., filamentous nitrogen-fixing cyanobacteria, Suc synthase (SuS, EC 2.4.1.13) controls Suc cell level through the cleavage
of the disaccharide. The present work shows that there are two sus genes in Anabaena (Nostoc) sp. that are co-regulated regarding the nitrogen source; however, only susA accounts for the extractable SuS activity and for the control of the Suc level. Primer extension analysis has uncovered the
sequence of the Anabaena
susA and susB ammonium-activated putative promoters, which share a high sequence similarity with that of rbcLS encoding ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39) and other ammonium up-regulated genes. Moreover, susA and rbcLS expression is developmentally co-localized to the vegetative cells of the nitrogen-fixing cyanobacterial filaments. Our results
strongly suggest the existence of a regulatory network that would coordinate the expression of key genes for Suc and nitrogen
metabolism, carbon fixation, and development in Anabaena sp. |
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Keywords: | Anabaena sp Ammonium regulation Cyanobacteria Ribulose bisphosphate carboxylase/oxygenase Sucrose metabolism Sucrose synthase |
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