title: Accumulation of D1 polypeptide in tobacco plastids is regulated via the untranslated region of the psbA mRNA.
abstract: The plastid psbA mRNA is present in all tissues, while the encoded 32 kDa D1 protein of photosystem II accumulates tissue-specifically and in response to light. To study the regulation of D1 accumulation, a chimeric uidA gene encoding beta-glucuronidase (GUS) under control of the psbA 5'- and 3'-regulatory regions (224 and 393 bp, respectively), was integrated into the tobacco plastid genome. A high level of GUS accumulation in leaves and the lack of GUS in roots, with uidA mRNA present in both tissues, indicated tissue-specific accumulation of the chimeric gene product. Light-regulated accumulation of GUS in seedlings was shown. (i) Light-induced accumulation (100-fold) of GUS in etiolated cotyledons was accompanied by only a modest increase in mRNA levels. (ii) Inhibition of GUS synthesis was observed in cotyledons when light-grown seedlings were transferred to the dark, with no reduction in mRNA levels. Tissue-specific and light-regulated accumulation of GUS indicates that D1 accumulation is controlled via cis-acting regulatory elements in the untranslated region of the psbA mRNA. We propose that in tobacco, control of translation initiation is the primary mechanism regulating D1 protein accumulation.
authors.affiliation: Waksman Institute, Rutgers, State University of New Jersey, Piscataway 08855-0759.
authors.forename: J M
authors.initials: JM
authors.lastname: Staub
authors.forename: P
authors.initials: P
authors.lastname: Maliga
mesh_terms: D001426:Bacterial Proteins; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006651:Histocytochemistry; D008027:Light; D015388:Organelles / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010947:Plants, Toxic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D014018:Tissue Distribution; D014026:Nicotiana / Q000201:enzymology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D005966:Glucuronidase