Functional genomic studies of aldo–keto reductases

Petrash, J. Mark; Murthy, B. S.; Young, Michael; Morris, Kent; Rikimaru, Loryn; Griest, Terry A.; Harter, Theresa

doi:10.1016/s0009-2797(00)00258-1

Cited by 33 publications

(37 citation statements)

References 23 publications

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“…Intriguingly, Saccharomyces cerevisiae possesses an enzyme, Gre3p (AKR2B6), that is over 60% related to the xylose reductases, even though it is unable to utilize xylose and would therefore be expected to have no need for such an enzyme. In fact, the Gre3p enzyme has good activity towards Dxylose as well as other substrates [20,21], so its presence in the cell remains a mystery. Studies that have examined the substrate speci¢city pro¢les of the xylose reductases from other yeast have shown that they too are capable of reducing other substrates.…”

Section: Enzyme Activities Of Microbial Akrmentioning

confidence: 99%

“…Ypr1p is a very poor glycerol dehydrogenase, but it does have high reductase activity towards 2-methylbutyraldehyde, which may represent an endogenous substrate in vivo [21,25,26]. Gcy1p has been shown to be able to reduce D,L-glyceraldehyde and 4-nitrobenzaldehyde (4-NBA) [12], but awaits further characterization in terms of its substrate speci¢city.…”

Section: Enzyme Activities Of Microbial Akrmentioning

confidence: 99%

“…This strain showed little phenotypic di¡erences from the wild-type, under the conditions tested [35,36]. Deletion of genes encoding three other AKR from S. cerevisiae (AKR5F, AKR5E, and AKR3A1 (Gcy1p)) have similarly shown little e¡ect [21]. Disruption of the norA gene encoding norsolorinic acid dehydrogenase from Aspergillus parasiticus has also proved unsuccessful in demonstrating its role in a£atoxin biosynthesis, but this may be because of a gene duplication event [37].…”

Section: Evidence Of Function From Null Mutantsmentioning

confidence: 99%

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Microbial aldo-keto reductases

Ellis

2002

FEMS Microbiology Letters

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The aldo-keto reductases (AKR) are a superfamily of enzymes with diverse functions in the reduction of aldehydes and ketones. AKR enzymes are found in a wide range of microorganisms, and many open reading frames encoding related putative enzymes have been identified through genome sequencing projects. Established microbial members of the superfamily include the xylose reductases, 2,5-diketo-D-gluconic acid reductases and L-keto ester reductases. The AKR enzymes share a common (K/L) 8 structure, and conserved catalytic mechanism, although there is considerable variation in the substrate-binding pocket. The physiological function of many of these enzymes is unknown, but a variety of methods including gene disruptions, heterologous expression systems and expression profiling are being employed to deduce the roles of these enzymes in cell metabolism. Several microbial AKR are already being exploited in biotransformation reactions and there is potential for other novel members of this important superfamily to be identified, studied and utilized in this way. ß 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.Keywords : Aldo-keto reductase; Aldehyde ; Ketone Reduction of aldehydes and ketones in the microbial cellAldehydes and ketones are important intermediates in many metabolic pathways, including sugar metabolism, steroid biosynthesis, amino acid metabolism, and biosynthesis of secondary metabolites. In addition, microbial cells encounter aldehydic products of lipid peroxidation after exposure to oxidants and heavy metals [1], as well as directly from exogenous sources, including plant phytoallexins, toxins and synthetically derived chemicals in the environment. Because of the reactivity of the carbonyl group, many aldehydes and ketones are mutagenic representing a potential danger to microbial cells [2]. The ability to metabolize these compounds gives a selective advantage to any microorganisms that are exposed to them.Aldehydes and ketones can be metabolized by several enzyme systems including aldehyde dehydrogenases that can oxidize aldehydes to acids, and the well-characterized alcohol dehydrogenases, which include the short-chain dehydrogenase/reductase and medium-chain dehydrogenase/ reductase families (reviewed in [3,4]). The number and structural diversity of these latter enzyme families might be considered su⁄cient to account for the capacity of the cell to reduce aldehydes and ketones. However, members of another superfamily of enzymes, the aldo-keto reductases (AKR), are present in many microbial cells [5], suggesting an evolutionary convergence of function between the superfamilies. Knowledge of the AKR family has grown rapidly over the last decade, and it now contains over 60 members from across all species [6]. It is the intention of this minireview to present the current state of knowledge of the microbial members of the AKR superfamily, focussing in particular on the structural features and biochemical activities of the enzymes, how...

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Section: Enzyme Activities Of Microbial Akrmentioning

confidence: 99%

Section: Enzyme Activities Of Microbial Akrmentioning

confidence: 99%

Section: Evidence Of Function From Null Mutantsmentioning

confidence: 99%

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Microbial aldo-keto reductases

Ellis

2002

FEMS Microbiology Letters

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“…The K m for xylose suggests that this protein is a xylose reductase with the ability to reduce several other compounds, including arabinose, glyceraldehydes, methylglyoxal and β-keto esters (Kuhn et al, 1995;Rodríguez et al, 2000;Ford and Ellis, 2001;Petrash et al, 2001). The GRE3 gene has been shown to be induced by stress (Aguilera and Prieto, 2001) and to be regulated by the HOG pathway (Garay-Arroyo and Covarrubias, 1999).…”

Section: Introductionmentioning

confidence: 99%

Endogenous NADPH‐dependent aldose reductase activity influences product formation during xylose consumption in recombinant Saccharomyces cerevisiae

Bjerre

Jeppsson

Hahn‐Hägerdal

et al. 2003

Yeast

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Introduction of the xylose pathway from Pichia stipitis into Saccharomyces cerevisiae enables xylose utilization in recombinant S. cerevisiae. However, xylitol is a major by-product. An endogenous aldo-keto reductase, encoded by the GRE3 gene, was expressed at different levels in recombinant S. cerevisiae strains to investigate its effect on xylose utilization. In a recombinant S. cerevisiae strain producing only xylitol dehydrogenase (XDH) from P. stipitis and an extra copy of the endogenous xylulokinase (XK), ethanol formation from xylose was mediated by Gre3p, capable of reducing xylose to xylitol. When the GRE3 gene was overexpressed in this strain, the xylose consumption and ethanol formation increased by 29% and 116%, respectively. When the GRE3 gene was deleted in the recombinant xylose-fermenting S. cerevisiae strain TMB3001 (which possesses xylose reductase and XDH from P. stipitis, and an extra copy of endogenous XK), the xylitol yield decreased by 49% and the ethanol yield increased by 19% in anaerobic continuous culture with a glucose/xylose mixture. Biomass was reduced by 31% in strains where GRE3 was deleted, suggesting that fine-tuning of GRE3 expression is the preferred choice rather than deletion.

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“…Under some conditions, deletion of GRE3 can decrease xylitol production (42). Two other aldose reductase gene homologs, YPR1 and YJR096w, also encode enzymes requiring NADPH and can utilize xylose as a substrate, but they have much higher K m values for xylose than does Gre3p (29,41). Thus, several genes encoding aldose reductases that could utilize xylose are expressed in S. cerevisiae.…”

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confidence: 99%

Endogenous Xylose Pathway in Saccharomyces cerevisiae

Toivari

Salusjärvi

Ruohonen

et al. 2004

Appl Environ Microbiol

117

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The baker's yeast Saccharomyces cerevisiae is generally classified as a non-xylose-utilizing organism. We found that S. cerevisiae can grow on D-xylose when only the endogenous genes GRE3 (YHR104w), coding for a nonspecific aldose reductase, and XYL2 (YLR070c, ScXYL2), coding for a xylitol dehydrogenase (XDH), are overexpressed under endogenous promoters. In nontransformed S. cerevisiae strains, XDH activity was significantly higher in the presence of xylose, but xylose reductase (XR) activity was not affected by the choice of carbon source. The expression of SOR1, encoding a sorbitol dehydrogenase, was elevated in the presence of xylose as were the genes encoding transketolase and transaldolase. An S. cerevisiae strain carrying the XR and XDH enzymes from the xylose-utilizing yeast Pichia stipitis grew more quickly and accumulated less xylitol than did the strain overexpressing the endogenous enzymes. Overexpression of the GRE3 and ScXYL2 genes in the S. cerevisiae CEN.PK2 strain resulted in a growth rate of 0.01 g of cell dry mass liter ؊1 h ؊1 and a xylitol yield of 55% when xylose was the main carbon source.The pentose sugar xylose is a major constituent of lignocellulose. Saccharomyces cerevisiae cannot use xylose, instead converting it primarily to xylitol with only a small fraction going into biomass or ethanol (44,45). Recombinant xylose-metabolizing S. cerevisiae strains contain genes from the xylose-utilizing yeast Pichia stipitis coding enzymes for the first two steps in xylose conversion (23,38,46). However, the potential of S. cerevisiae's own enzymes, if they are overexpressed, has not been evaluated.In xylose-utilizing fungi, xylose reductase (XR) reduces xylose to xylitol, which is oxidized to xylulose by xylitol dehydrogenase (XDH). Xylulose is subsequently phosphorylated to xylulose 5-phosphate by xylulokinase and metabolized through the pentose phosphate pathway. S. cerevisiae cannot utilize xylose but can grow on xylulose (15, 43). Thus, the inability of S. cerevisiae to utilize xylose was attributed to its inability to convert xylose to xylulose (15), even though low XR and XDH activities are known in S. cerevisiae (4). A nonspecific aldose reductase, converting xylose to xylitol, was purified and characterized from S. cerevisiae (24); however, the genes coding for the putative XR and XDH enzymes remained unknown. The third enzyme in the xylose pathway, xylulokinase, is encoded by XKS1, a gene that has been cloned from, and probably is functional in, S. cerevisiae (19). Moderate increases in xylulokinase activity are beneficial in recombinant xylose-metabolizing S. cerevisiae strains (9,18,20,21,40).Based on the S. cerevisiae genome sequence (14), the Nterminal amino acid sequence of the previously purified aldoketo reductase corresponds to the open reading frame YHR104w (GRE3), which has 72% amino acid similarity to the XR enzyme of P. stipitis. This enzyme can reduce a wide variety of ketose substrates and requires a NADPH cofactor (24). The XR of P. stipitis can use either NADH or NADPH i...

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Functional genomic studies of aldo–keto reductases

Cited by 33 publications

References 23 publications

Microbial aldo-keto reductases

Microbial aldo-keto reductases

Endogenous NADPH‐dependent aldose reductase activity influences product formation during xylose consumption in recombinant Saccharomyces cerevisiae

Endogenous Xylose Pathway in Saccharomyces cerevisiae

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