Publications by authors named "Stephanie Dingwall"

3 Publications

  • Page 1 of 1

AcDCXR Is a Cowpea Aphid Effector With Putative Roles in Altering Host Immunity and Physiology.

Front Plant Sci 2020 15;11:605. Epub 2020 May 15.

Graduate Program in Biochemistry and Molecular Biology, University of California, Riverside, Riverside, CA, United States.

Cowpea, , is a crop that is essential to semiarid areas of the world like Sub-Sahara Africa. Cowpea is highly susceptible to cowpea aphid, , infestation that can lead to major yield losses. Aphids feed on their host plant by inserting their hypodermal needlelike flexible stylets into the plant to reach the phloem sap. During feeding, aphids secrete saliva, containing effector proteins, into the plant to disrupt plant immune responses and alter the physiology of the plant to their own advantage. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to identify the salivary proteome of the cowpea aphid. About 150 candidate proteins were identified including diacetyl/L-xylulose reductase (DCXR), a novel enzyme previously unidentified in aphid saliva. DCXR is a member of short-chain dehydrogenases/reductases with dual enzymatic functions in carbohydrate and dicarbonyl metabolism. To assess whether cowpea aphid DCXR (AcDCXR) has similar functions, recombinant AcDCXR was purified and assayed enzymatically. For carbohydrate metabolism, the oxidation of xylitol to xylulose was tested. The dicarbonyl reaction involved the reduction of methylglyoxal, an α-β-dicarbonyl ketoaldehyde, known as an abiotic and biotic stress response molecule causing cytotoxicity at high concentrations. To assess whether cowpea aphids induce methylglyoxal in plants, we measured methylglyoxal levels in both cowpea and pea () plants and found them elevated transiently after aphid infestation. Agrobacterium-mediated transient overexpression of AcDCXR in pea resulted in an increase of cowpea aphid fecundity. Taken together, our results indicate that AcDCXR is an effector with a putative ability to generate additional sources of energy to the aphid and to alter plant defense responses. In addition, this work identified methylglyoxal as a potential novel aphid defense metabolite adding to the known repertoire of plant defenses against aphid pests.
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http://dx.doi.org/10.3389/fpls.2020.00605DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7243947PMC
May 2020

The oxidation-reduction and electrocatalytic properties of CO dehydrogenase from Oligotropha carboxidovorans.

Biochim Biophys Acta Bioenerg 2020 01 14;1861(1):148118. Epub 2019 Nov 14.

School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia. Electronic address:

CO dehydrogenase (CODH) from the Gram-negative bacterium Oligotropha carboxidovorans is a complex metalloenzyme from the xanthine oxidase family of molybdenum-containing enzymes, bearing a unique binuclear Mo-S-Cu active site in addition to two [2Fe-2S] clusters (FeSI and FeSII) and one equivalent of FAD. CODH catalyzes the oxidation of CO to CO with the concomitant introduction of reducing equivalents into the quinone pool, thus enabling the organism to utilize CO as sole source of both carbon and energy. Using a variety of EPR monitored redox titrations and spectroelectrochemistry, we report the redox potentials of CO dehydrogenase at pH 7.2 namely Mo, Mo, FeSI, FeSII, FAD/FADH and FADH/FADH. These potentials are systematically higher than the corresponding potentials seen for other members of the xanthine oxidase family of Mo enzymes, and are in line with CODH utilising the higher potential quinone pool as an electron acceptor instead of pyridine nucleotides. CODH is also active when immobilised on a modified Au working electrode as demonstrated by cyclic voltammetry in the presence of CO.
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http://dx.doi.org/10.1016/j.bbabio.2019.148118DOI Listing
January 2020

The aerobic CO dehydrogenase from Oligotropha carboxidovorans.

J Biol Inorg Chem 2015 Mar 26;20(2):243-51. Epub 2014 Aug 26.

Department of Biochemistry, University of California, Riverside, CA, 92521, USA,

We review here the recent literature dealing with the molybdenum- and copper-dependent CO dehydrogenase, with particular emphasis on the structure of the enzyme and recent advances in our understanding of the reaction mechanism of the enzyme.
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http://dx.doi.org/10.1007/s00775-014-1188-4DOI Listing
March 2015
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