Abstract
The expression of the various members of the zein multigene family in maize endosperm is controlled by different regulatory loci. One of these loci, Opaque-2, coding for a bZIP transcriptional factor, controls the expression of a subset of zein genes. Analysis of genomic DNA from plants carrying wild-type (O2) or mutant o2 alleles shows specific DNA restriction patterns that correlate with transcript types and their various gene products. Northern and western analyses show the presence in different wild types of a 1.7 kb transcript coding for different sizes of normal O2 proteins that migrate as doublets in the 68–72 kDa range. Among the various o2 mutants analysed we showed the occurrence of various null-transcript alleles, the presence of alleles with a normal size transcript which, however, produce a different-sized o2 protein, and a mutant producing both a normal size transcript and a longer transcript, but generating only a single o2 product migrating around 40 kDa. Analysis of other mutations (o7, fl2) known to affect zien polypeptide synthesis shows no interference of these mutations in the expression of the O2 gene products. The overall results indicate the occurrence of micro heterogeneity in the O2 wild-type genes and a broad spectrum of o2 mutations, both producing different sizes of O2 or o2 proteins. A nomenclature of the O2 and o2 genes based on the RFLP, transcripts and products of the various alleles is presented.
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References
Aukerman MJ, Schmidt RJ, Burr B, Burr FA: An arginine to lysine substitution in the bZIP domain of an opaque-2 mutant in maize abolishes specific DNA binding. Genes Devel 5: 310–320 (1991).
Bianchi MW, Viotti A: DNA methylation and tissue-specific transcription of the storage protein genes of maize. Plant Mol Biol 11: 203–214 (1988).
Dolfini SF, Landoni M, Tonelli C, Bernard L, Viotti A: Spatial regulation in the expression of structural and regulatory storage-protein genes in Zea mays endosperm. Devel Genet 13: 264–276 (1992).
Faust PL, Wall DA, Perara E, Lingappa VR, Kornfeld S: Expression of human cathepsin D in Xenopus Oocytes: phosphorylation and intracellular targeting. J Cell Biol 105: 1937–1945 (1987).
Hartings H, Maddaloni M, Di Fonzo N, Motto M, Salamini F, Thompson R: The O2 gene which regulates zein deposition in maize endosperm encodes a protein with structural homologies to transcriptional activators. EMBO J 8: 2795–2801 (1989).
Hunter T, Karin M: The regulation of transcription by phosphorylation. Cell 70: 375–387 (1992).
Jackson SP, Tjian R: O-Glycosylation of eukaryotic transcription factors: implications for mechanisms of transcriptional regulation. Cell 5: 125–133 (1988).
Kodrzycki R, Boston RS, Larkins BA: The opaque-2 mutation of maize differentially reduces zein gene transcription. Plant Cell 1: 105–114 (1989).
Liang CP, Lee YC, Liu YC: Deletion studies to reveal the basis for size discrepancy in proliferating cell nuclear antigen. Electrophoresis 13: 346–353 (1992).
Lohmer S, Maddaloni M, Motto M, Salamini F, Thompson RD: Translation of the mRNA of the maize transcriptional activator Opaque-2 is inhibited by upstream open reading frames present in the leader sequence. Plant Cell 5: 65–73 (1993).
MacConnell WP, Verma IM: Expression of FBJ-MSV oncogene (fos) product in bacteria. Virology 131: 367–374 (1983).
Maddaloni M, Di Fonzo N, Hartings H, Lazzaroni N, Salamini F, Thompson R, Motto M: The sequence of the zein regulatory gene Opaque-2 (O2) of Zea mays. Nucl Acids Res 17: 7532 (1989).
Marks MD, Lindell JS, Larkins BA: Nucleotide sequence analysis of zein mRNAs from maize endosperm. J Biol Chem 260: 16451–16459 (1985).
Motto M, Di Fonzo N, Hartings H, Maddaloni M, Salamini F, Soave C, Thompson RD: Regulatory genes affecting fecting maize storage protein synthesis. Oxford Surv Plant Mol Biol Cell Biol 6: 87–114 (1989).
Nelson OE: Un gene mutante che influenza la sintesi delle proteine nell'endosperma di mais. Maydica 12: 81–96 (1967).
Peterson GL: A simplification of the protein assay method of Lowry et al. which is more generally applicable. Anal Biochem 83: 346–356 (1977).
Salamini F: Controlling elements at the Opaque-2 locus of maize: Their involvement in the origin of spontaneous mutation. Cold Spring Harbor Symp Quant Biol 45: 467–476 (1980).
Schmidt RJ, Burr FA, Burr B: Transposon tagging and molecular analysis of the maize regulatory locus Opaque-2. Science 238: 960–963 (1987).
Schmidt RJ, Burr FA, Aukerman MJ, Burr B: Maize regulatory gene Opaque-2 encodes a protein with a ‘leucine-zipper’ motif that binds to zein DNA. Proc Natl Acad Sci 87: 46–50 (1990).
Schmidt RJ, Ketudat M, Aukerman MJ, Hoschek G: Opaque-2 is a transcriptional activator that recognizes a specific target site in 22-kD zein genes. Plant Cell 4: 689–700 (1992).
Schmidt RJ: Opaque-2 and zein gene expression. In: Verma DPS (ed.) Control of Plant Gene Expression, pp. 337–355. CRC Press, Boca Raton (1993).
Steele JCH, Nielsen TB: Evaluation of cross-linked polypeptides in SDS gel electrophoresis. Anal Biochem 84: 218–224 (1978).
Varagona MJ, Schmidt RJ, Raikhel NV: Monocot regulatory protein Opaque-2 is localized in the nucleus of maize endosperm and transformed tobacco plants. Plant Cell 3: 105–113 (1991).
Vitale A, Soave C, Galante E: Peptide mapping of IEF zein components from maize. Plant Sci Lett 18: 57–64 (1980).
Viotti A, Sala E, Marotta E, Alberi P, Balducci C, Soave C: Genes and mRNAs coding for zein polypeptides in Zea mays. Eur J Biochem 102: 211–222 (1979).
Viotti A, Abildsten D, Pogna N, Sala E, Pirrotta V: Multiplicity and diversity of cloned zein cDNA sequences and their chromosomal localisation. EMBO J 1: 53–58 (1982).
Viotti A, Cairo G, Vitale A, Sala E: Each zein gene class can produce polypeptides of different sizes. EMBO J 4: 1103–1110 (1985).
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Bernard, L., Ciceri, P. & Viotti, A. Molecular analysis of wild-type and mutant alleles at the Opaque-2 regulatory locus of maize reveals different mutations and types of O2 products. Plant Mol Biol 24, 949–959 (1994). https://doi.org/10.1007/BF00014448
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DOI: https://doi.org/10.1007/BF00014448