Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.2.13 (aldolase)
 3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Escherichia coli, L-fucose is dissimilated via an inducible pathway mediated by L-fucose permease, L-fucose isomerase, L-fucose kinase, and L-fuculose 1-phosphate aldolase. The last enzyme cleaves the six-carbon substrate into dihydroxyacetone phosphate and L-lactaldehyde. Aerobically, lactaldehyde is oxidized to L-lactate by a nicotinamide adenine dinucleotide (NAD)-linked dehydrogenase. Anaerobically, lactaldehyde is reduced by an NADH-COUPLED REDUCTASE TO L-1,2-propanediol, which is lost into the medium irretrievably, even when oxygen is subsequently introduced. Propanediol excretion is thus the end result of a dismutation that permits further anaerobic metabolism of dihydroxy-acetone phosphate. A mutant selected for its ability to grow aerobically on propanediol as a carbon and energy source was reported to produce lactaldehyde reductase constitutively and at high levels, even aerobically. Under the new situation, this enzyme serves as a propanediol dehydrogenase. It was also reported that the mutant had lost the ability to grow on fucose. In the present study, it is shown that in wild-type cells the full synthesis of lactaldehyde dehydrogenase requires the presence of both molecular oxygen and a small molecule effector, and the full synthesis of lactaldehyde reductase requires anaerobiosis and the presence of a small molecule effector. The failure of mutant cells to grow on fucose reflects the impairment of a regulatory element in the fucose system that prevents the induction of the permease, the isomerase, and the kinase. The aldolase, on the other hand, is constitutively synthesized. Three independent fucose-utilizing revertants of the mutant all produce the permease, the isomerase, the kinase, as well as the aldolase, constitutively. These strains grow less well than the parental mutant on propanediol.
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PMID:Disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in Escherichia coli. 18 64

Wild-type Escherichia coli cannot grow on L-1,2-propanediol; mutants that can do so have increased basal activity of an NAD-linked L-1,2-propanediol oxidoreductase. This enzyme belongs to the L-fucose system and functions normally as L-lactaldehyde reductase during fermentation of the methylpentose. In wild-type cells, the activity of this enzyme is fully induced only anaerobically. Continued aerobic selection for mutants with an improved growth rate on L-1,2-propanediol inevitably leads to full constitutive expression of the oxidoreductase activity. When this occurs, L-fuculose 1-phosphate aldolase concomitantly becomes constitutive, whereas L-fucose permease, L-fucose isomerase, and L-fuculose kinase become noninducible. It is shown in this study that the noninducibility of the three proteins can be changed by two different kinds of suppressor mutations: one mapping external to and the other within the fuc gene cluster. Both mutations result in constitutive synthesis of the permease, the isomerase, and the kinase, without affecting synthesis of the oxidoreductase and the aldolase. Since expression of the fuc structural genes is activated by a protein specified by the regulator gene fucR, and since all the known genes of the fuc system are clustered at minute 60.2 of the chromosome, the external gene in which the suppressor mutation can occur probably has an unrelated function in the wild-type strain. The internal suppressor mutation might be either in fucR or in the promoter region of the genes encoding the permease, the isomerase, and the kinase, if these genes belong to the same operon.
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PMID:Constitutive activation of L-fucose genes by an unlinked mutation in Escherichia coli. 637 90

Dihydroxyacetone variants have been explored as donors in organocatalytic aldol reactions with various aldehyde and ketone acceptors. The protected form of dihydroxyacetone that was chosen for in-depth study was 2,2-dimethyl-1,3-dioxan-5-one, 1. Among the catalysts surveyed here, proline proved to be superior in terms of yield and stereoselectivities in the construction of various carbohydrate scaffolds. In a fashion analogous to aldolase enzymes, the de novo preparation of L-ribulose, L-lyxose, D-ribose, D-tagatose, 1-amino-1-deoxy-D-lyxitol, and other carbohydrates was accomplished via the use of 1 and proline. In reactions using 2,2-dimethyl-1,3-dioxan-5-one 1 as a donor, (S)-proline can be used as a functional mimic of tagatose aldolase, whereas (R)-proline can be regarded as an organocatalytic mimic of fuculose aldolase.
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PMID:Dihydroxyacetone variants in the organocatalytic construction of carbohydrates: mimicking tagatose and fuculose aldolases. 1667 55

In this paper, we report that fluoride ion is converted to the amino acid/antibiotic 4-fluorothreonine 2 in a biotransformation involving five (steps a-e) overexpressed enzymes. The biotransformation validates the biosynthetic pathway to 4-fluorothreonine in the bacterium Streptomyces cattleya (Schaffrath et al., 2002). To achieve an in vitro biotransformation, the fluorinase and the purine nucleoside phosphorylase (PNP) enzymes (steps a and b), which are coded for by the flA and flB genes of the fluorometabolite gene cluster in S. cattleya, were overexpressed. Also, an isomerase gene product that can convert 5-FDRP 6 to 5-FDRibulP 7 (step c) was identified in S. cattleya, and the enzyme was overexpressed for the biotransformation. A fuculose aldolase gene from S. coelicolor was overexpressed in E. coli and was used as a surrogate aldolase (step d) in these experiments. To complete the complement of enzymes, an ORF coding the PLP-dependent transaldolase, the final enzyme of the fluorometabolite pathway, was identified in genomic DNA by a reverse genetics approach, and the S. cattleya gene/enzyme was then overexpressed in S. lividans. This latter enzyme is an unusual PLP-dependent catalyst with some homology to both bacterial serine hydroxymethyl transferases (SHMT) and C5 sugar isomerases/epimerases. The biotransformation demonstrates the power of the fluorinase to initiate C-F bond formation for organo-fluorine synthesis.
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PMID:In vitro reconstituted biotransformation of 4-fluorothreonine from fluoride ion: application of the fluorinase. 1910 71

Fuculose phosphate aldolase catalyzes the reversible cleavage of fuculose-1-phosphate to dihydroxyacetone phosphate and L-lactaldehyde. A tetramer by nature, this enzyme from Thermus thermophilus HB8 represents the group of Class II aldolases. The structure was solved in two different space groups using the crystals obtained from slow evaporation vapour-diffusion and microbatch techniques. The detailed crystallization description has been reported previously. In this study, the structural features of fuculose phosphate aldolase from T. thermophilus have been explored extensively through sequence and structure comparisons with fuculose phosphate aldolases of different species. Finally, an in silico analysis using induced fit docking was attempted to deduce the binding mode of fuculose phosphate aldolase with its natural substrate fuculose-1-phosphate along with a substrate analog dihydroxyacetone phosphate and phosphoglycolohydroxymate--a potential aldolase inhibitor. The results show the mechanism of action may be similar to that of Escherichia coli fuculose aldolase.
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PMID:Crystal structure analysis of L-fuculose-1-phosphate aldolase from Thermus thermophilus HB8 and its catalytic action: as explained through in silico. 2374 84