Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an effort towards understanding the biochemical properties and physiological functions of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase homologues, we have isolated three ACC oxidase clones from sunflower (Helianthus annuus) seedlings. ACCO1 is a cDNA clone while ACCO2 and ACCO3 and reverse transcriptase-polymerase chain reaction clones. Southern analysis indicated the existence of at least three members in the sunflower ACC oxidase gene family. Expression studies showed that ACCO3 was equally expressed in leaves, hypocotyl, and roots of sunflower seedlings, but it constituted only a small amount of the total ACC oxidase transcripts. In contrast, ACCO1 and ACCO2 were differentially expressed in these organs. ACCO1 mRNA was most abundant in roots, whereas ACCO2 was the major homologue in leaves and in hypocotyl. The levels of total ACC oxidase transcripts in these organs were also determined. High ACC oxidase transcript levels were associated with tissue containing rapidly dividing cells. Wounding and silver ion treatments of hypocotyls increased ACC oxidase mRNA levels and ACC oxidase activity; these events being consistent with the increases in ethylene production. In contrast, ACC oxidase protein levels were not affected by these treatments, suggesting that either a translational regulation and/or a rapid turn-over of the protein is involved in both wound- and silver ion-induced gene expression. Contrary to data in the literature, we found that auxins, ethephon and ACC did not affect ACC oxidase mRNA levels in sunflower hypocotyls. The complexity of ACC oxidase regulation and the significance of organ differential expression of ACC oxidase genes are discussed.
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PMID:Differential and wound-inducible expression of 1-aminocylopropane-1-carboxylate oxidase genes in sunflower seedlings. 929 Jun 44

During gravitropism, the accumulation of auxin in the lower side of the stem causes increased growth and the subsequent curvature, while the gaseous hormone ethylene plays a modulating role in regulating the kinetics of growth asymmetries. Light also contributes to the control of gravitropic curvature, potentially through its interaction with ethylene biosynthesis. In this study, red-light pulse treatment of etiolated pea epicotyls was evaluated for its effect on ethylene biosynthesis during gravitropic curvature. Ethylene biosynthesis analysis included measurements of ethylene; the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC); malonyl-conjugated ACC (MACC); and expression levels of pea ACC oxidase (Ps-ACO1) and ACC synthase (Ps-ACS1, Ps-ACS2) genes by reverse transcriptase-polymerase chain reaction analysis. Red-pulsed seedlings were given a 6 min pulse of 11 micromoles m-2 s-1 red-light 15 h prior to horizontal reorientation for consistency with the timeline of red-light inhibition of ethylene production. Red-pulse treatment significantly reduced ethylene production and MACC levels in epicotyl tissue. However, there was no effect of red-pulse treatment on ACC level, or expression of ACS or ACO genes. During gravitropic curvature, ethylene production increased from 60 to 120 min after horizontal placement in both control and red-pulsed epicotyls. In red-pulsed tissues, ACC levels increased by 120 min after horizontal reorientation, accompanied by decreased MACC levels in the lower portion of the epicotyl. Overall, our results demonstrate that ethylene production in etiolated epicotyls increases after the initiation of curvature. This ethylene increase may inhibit cell growth in the lower portion of the epicotyl and contribute to tip straightening and reduced overall curvature observed after the initial 60 min of curvature in etiolated pea epicotyls.
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PMID:Red light regulation of ethylene biosynthesis and gravitropism in etiolated pea stems. 1576 63