Category: Publications

COP1, AN ARABIDOPSIS REGULATORY GENE, ENCODES A PROTEIN WITH BOTH A ZINC-BINDING MOTIF AND A G BETA HOMOLOGOUS DOMAIN

Citation:

Deng, XW, Matsui M, Wei N, Wagner D, Chu AM, Feldmann KA, Quail PH.  1992.  COP1, an Arabidopsis regulatory gene, encodes a protein with both a zinc-binding motif and a G beta homologous domain, Nov 27. Cell. 71:791-801., Number 5

Abstract:

Plant seedling development is capable of following 1 of 2 distinct morphogenic pathways: skotomorphogenesis in darkness and photomorphogenesis in light. Dark-grown Arabidopsis seedlings with recessive mutations at the constitutively photomorphogenic (COP1) locus indicate that the wild-type COP1 protein represses photomorphogenesis in darkness and that light reverses this repressive activity. Using a T-DNA-tagged mutant, we have cloned the COP1 locus. The amino-terminal half of the encoded protein contains a conserved zinc-binding motif, whereas the carboxyl-terminal half contains a domain homologous to the WD-40 repeat motif of G beta proteins. The presence of both a putative DNA-binding motif and a G protein-related domain in a single polypeptide suggests that COP1 may be the first of a new class of regulatory molecules. This novel structure could endow COP1 with the capacity to function as a negative transcriptional regulator capable of direct interaction with components of the G protein signaling pathway.

Notes:

Deng, X WMatsui, MWei, NWagner, DChu, A MFeldmann, K AQuail, P H1-R29-GM47850-01/GM/NIGMS NIH HHS/Cell. 1992 Nov 27;71(5):791-801.

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OVEREXPRESSION OF PHYTOCHROME B INDUCES A SHORT HYPOCOTYL PHENOTYPE IN TRANSGENIC ARABIDOPSIS

Citation:

Wagner, D, Tepperman JM, Quail PH.  1991.  Overexpression of Phytochrome B Induces a Short Hypocotyl Phenotype in Transgenic Arabidopsis, Dec. The Plant cell. 3:1275-1288., Number 12

Abstract:

The photoreceptor phytochrome is encoded by a small multigene family in higher plants. phyA encodes the well-characterized etiolated-tissue phytochrome. The product of the phyB gene, which has properties resembling those of “green tissue” phytochrome, is as yet poorly characterized. We have developed a phytochrome B overexpression system for analysis of the structure and function of this protein. Using newly generated polyclonal and monoclonal antibodies that are selective for phytochrome B, we have demonstrated high levels of expression of full-length rice and Arabidopsis phytochrome B under the control of the cauliflower mosaic virus 35S promoter in transgenic Arabidopsis. The overexpressed phytochrome is spectrally active, undergoes red/far-red-light-dependent conformational changes, is synthesized in its inactive red light-absorbing form, and is stable in the light. Overexpression of phytochrome B is tightly correlated with a short hypocotyl phenotype in transgenic seedlings. This phenotype is strictly light dependent, thus providing direct evidence that phytochrome B is a biologically functional photoreceptor. Based on similarities to phenotypes obtained by overexpression of phytochrome A, it appears that phytochromes A and B can control similar responses in the plant.

Notes:

Wagner, D.Tepperman, J. M.Quail, P. H.Plant Cell. 1991 Dec;3(12):1275-1288.

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THE CALCIUM REQUIREMENT FOR STABILITY AND ENZYMATIC ACTIVITY OF TWO ISOFORMS OF BARLEY ALEURONE ALPHA-AMYLASE

Citation:

Bush, DS, Sticher L, van Huystee R, Wagner D, Jones RL.  1989.  The calcium requirement for stability and enzymatic activity of two isoforms of barley aleurone alpha-amylase, Nov 15. The Journal of biological chemistry. 264:19392-8., Number 32

Abstract:

alpha-Amylases (EC 3.2.1.1) secreted by the aleurone layer of barley grains are Ca2+-containing metalloenzymes. We studied the effect of Ca2+ on the activity and structure of the two major groups of aleurone alpha-amylase by incubating affinity purified enzyme in solutions containing Ca2+ from pCa 4 to 7. Both groups of isoforms required one atom of Ca2+/molecule of enzyme as determined by isotope exchange, but the two groups differed by more than 10-fold in their affinity for Ca2+. Both groups of alpha-amylase were irreversibly inactivated by incubation in low Ca2+ (pCa 7). This inactivation was not due to changes in primary structure, as measured by molecular weight, but appeared to be the result of changes in secondary and tertiary structure as indicated by circular dichroism spectra, serology, lability in the presence of protease, and fluorescence spectra. Analysis of the predicted secondary structure of barley aleurone alpha-amylase indicates that the Ca2+-binding region of barley amylases is structurally similar to that of mammalian alpha-amylases. Our data indicate that micromolar levels of Ca2+ are required to stabilize the structure of barley alpha-amylases in the endoplasmic reticulum of the aleurone layer where these enzymes are synthesized.

Notes:

Bush, D SSticher, Lvan Huystee, RWagner, DJones, R LJ Biol Chem. 1989 Nov 15;264(32):19392-8.

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