Sequence-specific interaction between S1F, a spinach nuclear factor, and a negative cis-element conserved in plastid-related genes. |
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Authors: | D X Zhou Y F Li M Rocipon R Mache |
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Institution: | Laboratoire de Biologie Moléculaire Végétale, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1178, Université J. Fourier, Grenoble, France. |
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Abstract: | The nuclear gene rps1 coding for the spinach plastid ribosomal protein CS1 exhibits both a constitutive and leaf-specific expression pattern. In contrast to other chloroplast-related genes like rbcS and cab, the leaf induction of rps1 expression is light-independent. These unique features of rps1 expression provide good models to study the mechanisms regulating plastid development and differentiation in higher plants. We report on the identification of a spinach leaf nuclear factor, designated S1F, interacting with the rps1 promoter. The S1F binding site is conserved in the promoter region of many plastid-related genes, including rbcS, cab, and rpl21. A binding activity similar to S1F was detected in nuclear extract from dark-grown de-differentiated soybean suspension cells. Through site-specific mutagenesis and transient expression in soybean cell protoplasts, we show that the S1F binding site is a negative element down-regulating the promoter activity of rps1. A ligated tetramer of S1F site was able to repress activity of the cauliflower mosaic virus 35 S promoter extending the negative function of the S1F binding site on promoter activity. |
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