Localization and Conditional Redundancy of Regulatory Elements in rbcS-3A, a Pea Gene Encoding the Small Subunit of Ribulose-bisphosphate Carboxylase

• Published in: Proceedings of the National Academy of Sciences - PNAS 1988-07, Vol.85 (13), p.4662-4666
• Main Authors: Kuhlemeier, Cris, Cuozzo, Maria, Green, Pamela J., Goyvaerts, Elisabeth, Ward, Kathy, Chua, Nam-Hai
• Format: Article
• Language: English
• Subjects: Base Sequence; Biological and medical sciences; DNA; Fabaceae - enzymology; Fabaceae - genetics; Fundamental and applied biological sciences. Psychology; Genes; Genes - radiation effects; Genetic mutation; Leaves; Light; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Nucleotides; Organ Specificity; Peas; Pisum sativum; Plant Proteins - genetics; Plants, Medicinal; Regulatory Sequences, Nucleic Acid - radiation effects; Reporter genes; Ribulose-Bisphosphate Carboxylase - genetics; RNA; Seedlings; Transcription. Transcription factor. Splicing. Rna processing; Transgenic plants
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.13.4662

Expression of the pea rbcS-3A gene, one of a family of genes encoding the small subunit of ribulose-bisphosphate carboxylase [EC 4.1.1.39], is regulated by light and is restricted to chloroplast-containing cells. We analyzed the effects of light and development on rbcS-3A expression in transgenic plants. Two highly conserved sequences (``boxes'' II and III) around nucleotide position -150 (relative to the transcription initiation site, +1) are required for rbcS-3A expression. The so-defined positive elements overlap with previously identified negative light-regulatory elements. In the case of box II, which has sequence similarity to the core enhancer motif of simian virus 40, a GG→ CC transversion is sufficient to abolish expression. The effect of mutations in boxes II and III can only be measured when sequences upstream of -170 are removed, because sequences both 5′ and 3′ of -170 can direct light-regulated and organ-specific expression. This implies that there is a redundancy of cis-acting elements in the 5′ noncoding region of rbcS-3A. However, we show that the sequences upstream of -170 are dispensable only in the mature leaves of a green plant. In contrast, in the young, expanding leaves at the top of a green plant, as well as in seedlings, the distal elements are required for high-level expression. Therefore, redundancy is not absolute, and the requirements for rbcS-3A expression change during plant development.