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..74 microM), and non-time-dependent manner. The potent enzyme inhibition would be caused by specific binding to the enzyme, and by scavenging reactive oxygen species required for the monooxygenase reaction...

..Manipulation of the functionally divergent type III PKSs by a nonphysiological substrate thus provides an efficient method for production of pharmaceutically important quinolone alkaloids...

..These aromatic residues are likely to be located at the substrate-binding domain of the active-site, and control the stereochemical course of the enzyme reaction...

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..126 References are cited...

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..This provided new insights into the catalytic functions and specificities of the CHS-superfamily type III PKS enzymes...

..This provided novel strategies for the engineered biosynthesis of pharmaceutically important plant polyketides...

..Finally, Ser338 in proximity of the catalytic Cys164 guides the linear polyketide intermediate to extend into the pocket, thus leading to formation of the hepataketide in Rheum palmatum ALS...

..The functional conversion is based on the simple steric modulation of a chemically inert residue lining the active-site cavity...

..A homology model predicted that the active-site cavity volume of the triple mutant is increased to 4 times that of the wild-type PCS...

..The regulation of the level of the glucocorticoid-induced gene expression by the antioxidative gallates is of great interest from a therapeutic point of view...

..Isoprenyl gallates (4-6) showed good inhibition (IC50 = 1.5 5.1 microM), as potent as previously reported substrate analogues, while phenylalkyl gallates (7-10) were moderate inhibitors of the enzyme (IC50 = 12-61 microM)...

..83 microM) showed potent enzyme inhibition at the submicromolar concentration range, while esters with shorter chain lengths (C(1)-C(4)) and a C(18) ester exhibited moderate inhibition (IC(50) = 8-47 microM)...

..cerevisiae OSLC), were chosen for site-directed mutagenesis experiments; H234E, H234Y, H234F, D456E, D456N, and D456H mutants were inactive, while H234W and H234K mutants retained lanosterol-forming activity...

..Molecular modeling predicted that EGCG binds to the enzyme in the proximity of the FAD binding site via formation of three hydrogen bonds...

..In contrast, succinyl-CoA was not accepted as a substrate by the enzymes...

..033 microM) and no-time-dependent manner. The potent inhibition of the flavin monooxygenase would be caused by specific binding to the enzyme, and by scavenging reactive oxygen species required for the epoxidation reaction...

..The substrate should be folded in chair-chair-chair-chair-boat-boat conformation to achieve the stereochemistry of the cyclization product...

..On the other hand, the enzyme also accepted hexanoyl-CoA and methylmalonyl-CoA as substrates to produce an unnatural novel triketide, 4-hydroxy-3,5-dimethyl-6-pentyl-pyran-2-one...

..Finally, besides the phenylbutanones in rhubarb, BAS has been proposed to play a crucial role for the construction of the C6-C4 moiety of a variety of natural products such as medicinally important gingerols in ginger plant...

..Manipulation of the biosynthesis of polyketides by synthetic analogs could lead to the development of a chemical library of pharmaceutically interesting novel polyketides...

..Furthermore, by co-action of the CHS and the PKR, the NAC-thioesters were converted to 6'-deoxychalcone in the presence of NADPH and malonyl-CoA...

..Instead, homology modeling suggested a possibility that, unlike the case of CHS, BAS utilizes an alternative pocket to lock the coumaroyl moiety for the diketide formation reaction...

..This provides new insights into the catalytic functions of type III PKSs, and suggests further involvement in the biosynthesis of plant polyketides...

..These results confirmed the critical role of Phe-215 in the polyketide formation reactions and provided structural basis for understanding the structure-function relationship of the plant type III PKSs...

..Site-directed mutagenesis demonstrated that the A207G mutant dominantly produced the octaketides SEK4/SEK4b, whereas the A207M mutant yielded a pentaketide 5,7-dihydroxy-2-methylchromone...

..Interestingly, Hu. serrata polyketide synthase 1 lacks most of the consensus active site sequences with acridone synthase from Ruta graveolens (Rutaceae)...

..The findings suggested further strategies for production of unnatural polyketides by combination of the precursor-directed biosynthesis and the structure-guided engineering of type III PKS...

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..Interestingly, despite the low sequence identity, homology modeling revealed that the active-site architecture of PKS-A and PKS-B showed similarity to that of a bacterial type III PKS from Mycobacterium tuberculosis...

..Structure-based engineering of the type III PKS superfamily enzymes would thus lead to further production of chemically and structurally divergent unnatural novel polyketides...

..reaction: see text]..

..It is remarkable that the formation of the anti-Markovnikov six-membered D-ring did not depend on the participation of the terminal pi-electrons...

..Interestingly, 3-(geranylgeranyl)indole was not a substrate for the bacterial squalene cyclase, while 3-(farnesyldimethylallyl)indole was efficiently converted to a 2:1 mixture of unnatural novel products...

..Site-directed mutagenesis of a conserved Asp62, located right after the ATP/GTP binding motif, with Ala resulted in complete loss of enzyme activity...

..Taken together, the results indicate that UGT1A1 was induced in response to flavonoids and xenobiotics through the transactivation of the 290-bp reporter gene, that was a multi-component enhancer containing CAR, PXR and AhR motifs...

..These findings not only provided insight into the polyketide formation reaction, but they also suggested strategies for the engineered biosynthesis of polyketides...

..6, b = 89.6, c = 81.1 A, alpha = gamma = 90.0, beta = 100.5 degrees . Diffraction data were collected to 1.8 A resolution using synchrotron radiation at BL24XU of SPring-8...

..Finally, a homology model on the basis of the crystal structure of Hordeum vulgare AKR predicted the active-site architecture of the enzyme...

..The crystals belonged to space group I422, with unit-cell parameters a = b = 110.2, c = 281.4 A, alpha = beta = gamma = 90.0 degrees . Diffraction data were collected to 2.6 A resolution using synchrotron radiation at BL24XU of SPring-8...

..3, b = 85.0, c = 137.7 A, alpha = beta = gamma = 90.0 degrees. Diffraction data were collected to 2.0 A resolution using synchrotron radiation at BL24XU of SPring-8...

..2, b = 88.4, c = 70.0 A, alpha = gamma = 90.0, beta = 95.6 degrees . Diffraction data were collected to 1.6 A resolution using synchrotron radiation at BL24XU of SPring-8...

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..Narigenin-chalcone production by VPS was much lower than by CHS_H1. Therefore, it is highly possible that flavonoid depends mainly on CHS_H1, while bitter acid biosynthesis depends mainly on VPS and CHS_H1...

..These findings may have some relevance to other types of cataracts, inborn defects of cholesterol synthesis, and the effects of cholesterol-lowering medication...

..These results indicate that this analytical method for quantifying agaritine could help to evaluate the risk of mushroom hydrazines to humans...

..The results indicate that this specific and sensitive analytical method for detecting and quantifying agaritine and its derivatives could help evaluate the risk of mushroom hydrazines to humans...