KIYOTA, E.

KOCH, K. E.

SOUSA, S. M. de

YUNES, J. A.

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nMisine apoli.s # AU9uAt 6-10Abstract Center . Session List . Itinerary. Search: GoPoster: Gene Regulation & Molecular BiologyAdd this abstract to my ItineraryAbs # P14019: A role in sugar and redox handling for maize aldose reductasePresenter: de Sousa, Sylvia M Contact PresenterAuthors de Sousa, Sylvia M (A) (8) Kiyota, Eduardo (C) Yunes, Jose A (C) (D)Koch, Karen E (A)Affiliations: (A): University of Florida(B): Embrapa Maize and Sorghum(C): State University of Campinas(D): Boldrini Children's CenterOur initial interest in aldose reductase (AR) rose from its possible role in sorbitolmetabolism by maize kernels. AR is the only known enzyme in maize, other thansorbitol dehydrogenase, with capacity to synthesize or use the sorbitol soprominent in developing kernels (sorbitol + NADP êl~glucose + NADPH). Thereaction is reversible and could allow sorbitol use by embryos. Howeve r, ARs cancatalyze diverse reactions and may have multiple roles in sugar- and redox-handling. Aldo-keto reductases (AKRs) are widely distributed in nature and playnumerous roles in metabolism. In this study, we present eight putative AKRs inmaize and characterize one of them, AKR4C13, due to its embryo specificity.Each of these eight genes show differential expression in maize tissues duringdevelopment at mRNA and protein levels. Polyclonal antibodies raised against arecombinant maize AKR, reacted with severa I polypeptides that varied in amountamong tissues. Results were consistent with different roles for the AR-likeproteins. Data from western blots also agreed with predicted molecular weightsof the AR family members as well as their expression patterns. The AKR4C13was embryo-specific, with a MW of 35,659 Da and was temporally correlated withseed maturation and lipid biosynthesis in scutellum. The recombinant AKR4C13enzyme could reduce DL-glyceraldehyde (standard) and oxidize sorbitol, but notreduce D-glucose. One possibility is that the maize sorbitol pathway, and AR invivo, has similarities to roles in humans, where their primary effect is that ofbalancing sugar pools and redox levels under high-sugar conditions. Such ascenario could be especially valuable given the predicted gradients of sugarsand reducing power within the maize kernel.Abstract Center . Session List . Itinerary . Search: Gode 2 30/08/2(

A role in sugar and redox handling of maize aldose reductase.

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