The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Seiichi P T Matsuda - One of the best experts on this subject based on the ideXlab platform.
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Lanosterol biosynthesis in plants
Archives of Biochemistry and Biophysics, 2006Co-Authors: Mariya D Kolesnikova, Quanbo Xiong, Silvia Lodeiro, Seiichi P T MatsudaAbstract:Abstract Plants biosynthesize sterols from cycloartenol using a pathway distinct from the animal and fungal route through Lanosterol. Described herein are genome-mining experiments revealing that Arabidopsis encodes, in addition to cycloartenol synthase, an accurate Lanosterol synthase ( LSS )—the first example of Lanosterol synthases cloned from a plant. The coexistence of cycloartenol synthase and Lanosterol synthase implies specific roles for both cyclopropyl and conventional sterols in plants. Phylogenetic reconstructions reveal that Lanosterol synthases are broadly distributed in eudicots but evolved independently from those in animals and fungi. Novel catalytic motifs establish that plant Lanosterol synthases comprise a third catalytically distinct class of Lanosterol synthase.
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enzyme redesign two mutations cooperate to convert cycloartenol synthase into an accurate Lanosterol synthase
Journal of the American Chemical Society, 2005Co-Authors: Silvia Lodeiro, Tanja Schulzgasch, Seiichi P T MatsudaAbstract:Efforts to modify the catalytic specificity of enzymes consistently show that it is easier to broaden the substrate or product specificity of an accurate enzyme than to restrict the selectivity of one that is promiscuous. Described herein are experiments in which cycloartenol synthase was redesigned to become a highly accurate Lanosterol synthase. Several single mutants have been described that modify the catalytic specificity of cycloartenol to form some Lanosterol. Modeling studies were undertaken to identify combinations of mutations that cooperate to decrease the formation of products other than Lanosterol. A double mutant was constructed and characterized and was shown to cyclize oxidosqualene accurately to Lanosterol (99%). This catalytic change entailed both relocating polarity with a His477Asn mutation and modifying steric constraints with an Ile481Val mutation.
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directed evolution to generate cycloartenol synthase mutants that produce Lanosterol
Organic Letters, 2002Co-Authors: Michelle M Meyer, And Ran Xu, Seiichi P T MatsudaAbstract:Cycloartenol synthase converts oxidosqualene to cycloartenol, a pentacyclic isomer of the animal and fungal sterol precursor Lanosterol. We used directed evolution to find cycloartenol synthase residues that affect cyclopropyl ring formation, selecting randomly generated cycloartenol synthase mutants for their ability to genetically complement a yeast strain lacking Lanosterol synthase. To increase the likelihood of finding novel mutations, the little-studied Dictyostelium discoideum cycloartenol synthase was used for the mutagenesis. Several catalytically important residues were identified.
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Trypanosome and Animal Lanosterol Synthases Use Different Catalytic Motifs
Organic Letters, 2001Co-Authors: Bridget M. Joubert, Frederick S. Buckner, Seiichi P T MatsudaAbstract:Animals, fungi, and some protozoa convert oxidosqualene to Lanosterol in the ring-forming reaction in sterol biosynthesis. The Trypanosoma cruzi Lanosterol synthase has now been cloned. The sequence shares with the T. brucei Lanosterol synthase a tyrosine substitution for the catalytically important active-site threonine found in animal and fungal Lanosterol synthases.
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Steric bulk at position 454 in Saccharomyces cerevisiae Lanosterol synthase influences B-ring formation but not deprotonation.
Organic Letters, 2000Co-Authors: Bridget M. Joubert, Seiichi P T MatsudaAbstract:Lanosterol synthase converts oxidosqualene to the tetracyclic sterol precursor Lanosterol. The mutation experiments described here show that an active-site valine residue in Lanosterol synthase contributes to cyclization control through steric effects. Mutating to smaller alanine or glycine residues allows formation of the monocyclic achilleol A, whereas the leucine and isoleucine mutants make exclusively Lanosterol. The phenylalanine mutant is inactive.
Xiangjun Chen - One of the best experts on this subject based on the ideXlab platform.
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Lanosterol modulates proteostasis via dissolving cytosolic sequestosomes aggresome like induced structures
Biochimica et Biophysica Acta, 2020Co-Authors: Lidan Hu, Jing Wang, Xiangjun ChenAbstract:Abstract Sequestration of misfolded proteins into distinct cellular compartments plays a pivotal role in proteostasis and proteopathies. Cytoplasmic ubiquitinated proteins are sequestered by p62/SQSTM1 to deposit in sequestosomes or aggresome-like induced structures (ALIS). Most aggresome or ALIS regulators identified thus far are recruiters, while little is known about the disaggregases or dissolvers. In this research, we showed that Lanosterol synthase and its enzymatic product Lanosterol effectively reduced the number and/or size of sequestosomes/ALIS/aggresomes formed by endogenous proteins in the HeLa and HEK-293A cells cultured under both non-stressed and stressed conditions. Supplemented Lanosterol did not affect the proteasome and autophagic activities, but released the trapped proteins from the p62-positive inclusions accompanied with the activation of HSF1 and up-regulation of various heat shock proteins. Our results suggested that the coordinated actions of disaggregation by Lanosterol and refolding by heat shock proteins might facilitate the cells to recycle proteins from aggregates. The disaggregation activity of Lanosterol was not shared by cholesterol, indicating that Lanosterol possesses additional cellular functions in proteostasis regulation. Our findings highlight that besides protein modulators, the cells also possess endogenous low-molecular-weight compounds as efficient proteostasis regulators.
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Lanosterol modulates proteostasis via dissolving cytosolic sequestosomes/aggresome-like induced structures.
Biochimica et Biophysica Acta, 2019Co-Authors: Lidan Hu, Jing Wang, Xiangjun ChenAbstract:Abstract Sequestration of misfolded proteins into distinct cellular compartments plays a pivotal role in proteostasis and proteopathies. Cytoplasmic ubiquitinated proteins are sequestered by p62/SQSTM1 to deposit in sequestosomes or aggresome-like induced structures (ALIS). Most aggresome or ALIS regulators identified thus far are recruiters, while little is known about the disaggregases or dissolvers. In this research, we showed that Lanosterol synthase and its enzymatic product Lanosterol effectively reduced the number and/or size of sequestosomes/ALIS/aggresomes formed by endogenous proteins in the HeLa and HEK-293A cells cultured under both non-stressed and stressed conditions. Supplemented Lanosterol did not affect the proteasome and autophagic activities, but released the trapped proteins from the p62-positive inclusions accompanied with the activation of HSF1 and up-regulation of various heat shock proteins. Our results suggested that the coordinated actions of disaggregation by Lanosterol and refolding by heat shock proteins might facilitate the cells to recycle proteins from aggregates. The disaggregation activity of Lanosterol was not shared by cholesterol, indicating that Lanosterol possesses additional cellular functions in proteostasis regulation. Our findings highlight that besides protein modulators, the cells also possess endogenous low-molecular-weight compounds as efficient proteostasis regulators.
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synthesis evaluation and structure activity relationship study of Lanosterol derivatives to reverse mutant crystallin induced protein aggregation
Journal of Medicinal Chemistry, 2018Co-Authors: Xinglin Yang, Xiangjun Chen, Zimo Yang, Yibo Xi, Liguo Wang, Yue WuAbstract:We describe here the development of potent synthetic analogues of the naturally occurring triterpenoid Lanosterol to reverse protein aggregation in cataracts. Lanosterol showed superiority to other scaffolds in terms of efficacy and generality in previous studies. Various modified Lanosterol derivatives were synthesized via modification of the side chain, ring A, ring B, and ring C. Evaluation of these synthetic analogues draws a clear picture for SAR. In particular, hydroxylation of the 25-position in the side chain profoundly improved the potency, and 2-fluorination further enhanced the biological activity. This work also revealed that synthetic Lanosterol analogues could reverse multiple types of mutant-crystallin aggregates in cell models with excellent potency and efficacy. Notably, Lanosterol analogues have no cytotoxicity but can improve the viability of the HLE-B3 cell line. Furthermore, representative compound 6 successfully redissolved the aggregated crystallin proteins from the amyloid-like fib...
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Lanosterol reverses protein aggregation in cataracts
Nature, 2015Co-Authors: Ling Zhao, Lidan Hu, Xiangjun Chen, Yibo Xi, Xu Yang, Hong Ouyang, Sherrina Patel, Frances Wu, Ken FlaggAbstract:The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people1, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by Lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by Lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that Lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies Lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.
Wenshiang Shie - One of the best experts on this subject based on the ideXlab platform.
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Protein engineering of Saccharomyces cerevisiae oxidosqualene-Lanosterol cyclase into parkeol synthase.
Organic Letters, 2012Co-Authors: Tain Chang Hu, Wenshiang Shie, Chenghsiang Chang, Tungkung WuAbstract:A Saccharomyces cerevisiae oxidosqualene-Lanosterol cyclase mutant, ERG7T384Y/Q450H/V454I, produced parkeol but not Lanosterol as the sole end product. Parkeol undergoes downstream metabolism to generate compounds 9 and 10. In vitro incubation of parkeol produced a product profile similar to that of the in vivo experiment. In summary, parkeol undergoes a metabolic pathway similar to that of cycloartenol in yeast but distinct from that of Lanosterol in yeast, suggesting that two different metabolic pathways of postoxidosqualene cyclization may exist in S. cerevisiae.
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Mutation of isoleucine 705 of the oxidosqualene-Lanosterol cyclase from Saccharomyces cerevisiae affects Lanosterol's C/D-ring cyclization and 17α/β-exocyclic side chain stereochemistry
Organic and Biomolecular Chemistry, 2010Co-Authors: Tungkung Wu, Chenghsiang Chang, Yi-chun Chang, Wen-hsuan Li, Wenshiang ShieAbstract:Site-saturated substitution in Saccharomyces cerevisiaeoxidosqualene-Lanosterol cyclase at Ile705 position produced three chair-boat-chair (C–B–C) truncated tricyclic compounds, two 17α-exocyclic protosteryl intermediates, two protosteryl C-17 truncated rearranged intermediates and the normal biosynthetic product, Lanosterol. These results indicated the importance of the Ile705 residue in affecting Lanosterol's C/D ring stabilization including 6-6-5 tricyclic and protosteryl C-17 cations and 17α/β–exocyclic side chain stereochemistry.
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importance of saccharomyces cerevisiae oxidosqualene Lanosterol cyclase tyrosine 707 residue for chair boat bicyclic ring formation and deprotonation reactions
Organic Letters, 2008Co-Authors: Tungkung Wu, Tsaiting Wang, Chenghsiang Chang, Wenshiang ShieAbstract:A contact mapping strategy was applied to identify putative amino acid residues that influence the oxidosqualene-Lanosterol B-ring cyclization reaction. A bicyclic intermediate with two altered deprotonation products, in conjunction with Lanosterol, were isolated from the ERG7Y707X mutants, indicating that the Tyr707 residue may play a functional role in stabilizing the chair-boat bicyclic C-8 cation and the lanosteryl C-8/C-9 cation intermediates.
Tungkung Wu - One of the best experts on this subject based on the ideXlab platform.
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Protein engineering of Saccharomyces cerevisiae oxidosqualene-Lanosterol cyclase into parkeol synthase.
Organic Letters, 2012Co-Authors: Tain Chang Hu, Wenshiang Shie, Chenghsiang Chang, Tungkung WuAbstract:A Saccharomyces cerevisiae oxidosqualene-Lanosterol cyclase mutant, ERG7T384Y/Q450H/V454I, produced parkeol but not Lanosterol as the sole end product. Parkeol undergoes downstream metabolism to generate compounds 9 and 10. In vitro incubation of parkeol produced a product profile similar to that of the in vivo experiment. In summary, parkeol undergoes a metabolic pathway similar to that of cycloartenol in yeast but distinct from that of Lanosterol in yeast, suggesting that two different metabolic pathways of postoxidosqualene cyclization may exist in S. cerevisiae.
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Mutation of isoleucine 705 of the oxidosqualene-Lanosterol cyclase from Saccharomyces cerevisiae affects Lanosterol's C/D-ring cyclization and 17α/β-exocyclic side chain stereochemistry
Organic and Biomolecular Chemistry, 2010Co-Authors: Tungkung Wu, Chenghsiang Chang, Yi-chun Chang, Wen-hsuan Li, Wenshiang ShieAbstract:Site-saturated substitution in Saccharomyces cerevisiaeoxidosqualene-Lanosterol cyclase at Ile705 position produced three chair-boat-chair (C–B–C) truncated tricyclic compounds, two 17α-exocyclic protosteryl intermediates, two protosteryl C-17 truncated rearranged intermediates and the normal biosynthetic product, Lanosterol. These results indicated the importance of the Ile705 residue in affecting Lanosterol's C/D ring stabilization including 6-6-5 tricyclic and protosteryl C-17 cations and 17α/β–exocyclic side chain stereochemistry.
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importance of saccharomyces cerevisiae oxidosqualene Lanosterol cyclase tyrosine 707 residue for chair boat bicyclic ring formation and deprotonation reactions
Organic Letters, 2008Co-Authors: Tungkung Wu, Tsaiting Wang, Chenghsiang Chang, Wenshiang ShieAbstract:A contact mapping strategy was applied to identify putative amino acid residues that influence the oxidosqualene-Lanosterol B-ring cyclization reaction. A bicyclic intermediate with two altered deprotonation products, in conjunction with Lanosterol, were isolated from the ERG7Y707X mutants, indicating that the Tyr707 residue may play a functional role in stabilizing the chair-boat bicyclic C-8 cation and the lanosteryl C-8/C-9 cation intermediates.
John H. Griffin - One of the best experts on this subject based on the ideXlab platform.
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inhibition of 2 3 oxidosqualene Lanosterol cyclase in candida albicans by pyridinium ion based inhibitors
Antimicrobial Agents and Chemotherapy, 1996Co-Authors: Robert C Goldman, Bradley A Sharpe, John O Capobianco, Dorothy Zakula, John H. GriffinAbstract:The N-(4E,8E)-5,9,13-trimethyl-4,8,12-tetradecatrien-1- ylpyridinium and N-(4E,8E)-5,9,13-trimethyl-4,8,12-tetradecatrien-1- ylpicolinium cations were evaluated for their ability to inhibit 2,3-oxidosqualene-Lanosterol cyclase activity in Candida albicans. Both compounds inhibited fungal growth, were fungicidal, and resulted in the accumulation of squalene epoxide concurrent with a decrease in ergosterol, monomethyl sterols, and Lanosterol, as was expected for the specific inhibition of 2,3-oxidosqualene-Lanosterol cyclase activity. These compounds are electron-poor aromatic mimics of a monocyclized transition state or high-energy intermediate formed from oxidosqualene, which may explain their selective action.
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isolation and characterization of the gene encoding 2 3 oxidosqualene Lanosterol cyclase from saccharomyces cerevisiae
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Christopher J Buntel, John H. GriffinAbstract:Abstract The ERG7 gene encoding oxidosqualene-Lanosterol cyclase [(S)-2,3-epoxysqualene mutase (cyclizing, Lanosterol forming), EC 5.4.99.7] from Saccharomyces cerevisiae has been cloned by genetic complementation of a cyclase-deficient erg7 strain. The DNA sequence of this gene has been determined and found to contain an open reading frame of 2196 nt (including stop codon) that encodes a predicted protein of 731 amino acids. The predicted molecular mass of the S. cerevisiae cyclase, 83.4 kDa, is similar to the predicted molecular masses of the oxidosqualene-Lanosterol cyclase from Candida albicans and the oxidosqualene-cycloartenol cyclase from Arabidopsis thaliana, as well as to the molecular masses assigned to vertebrate oxidosqualene-Lanosterol cyclases; however, it is substantially larger than the molecular mass assigned to purified S. cerevisiae cyclase. At the level of DNA and predicted amino acid sequences, the S. cerevisiae and C. albicans cyclases share 56% and 63% identity, respectively. Tryptophan and tyrosine residues are unusually abundant in the predicted amino acid sequences of (oxido)-squalene cyclases, leading to a hypothesis that electron-rich aromatic side chains from these residues are essential features of cyclase active sites.
