Other search tools

About this data

The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.

If you have any questions or comments, please contact us.

Results: 1 to 7 of 7

Publication Record

Connections

Cytochrome P450 metabolism of the post-lanosterol intermediates explains enigmas of cholesterol synthesis.
Ačimovič J, Goyal S, Košir R, Goličnik M, Perše M, Belič A, Urlep Ž, Guengerich FP, Rozman D
(2016) Sci Rep 6: 28462
MeSH Terms: Animals, Cholesterol, Cyclic AMP Response Element Modulator, Cytochrome P-450 Enzyme System, Gas Chromatography-Mass Spectrometry, Humans, Lanosterol, Male, Mice, Mice, Knockout, Models, Theoretical, Oxidation-Reduction, Rats, Recombinant Proteins, Sterols, Testis
Show Abstract · Added March 14, 2018
Cholesterol synthesis is among the oldest metabolic pathways, consisting of the Bloch and Kandutch-Russell branches. Following lanosterol, sterols of both branches are proposed to be dedicated to cholesterol. We challenge this dogma by mathematical modeling and with experimental evidence. It was not possible to explain the sterol profile of testis in cAMP responsive element modulator tau (Crem τ) knockout mice with mathematical models based on textbook pathways of cholesterol synthesis. Our model differs in the inclusion of virtual sterol metabolizing enzymes branching from the pathway. We tested the hypothesis that enzymes from the cytochrome P450 (CYP) superfamily can participate in the catalysis of non-classical reactions. We show that CYP enzymes can metabolize multiple sterols in vitro, establishing novel branching points of cholesterol synthesis. In conclusion, sterols of cholesterol synthesis can be oxidized further to metabolites not dedicated to production of cholesterol. Additionally, CYP7A1, CYP11A1, CYP27A1, and CYP46A1 are parts of a broader cholesterol synthesis network.
0 Communities
1 Members
0 Resources
16 MeSH Terms
Human sterol 14α-demethylase as a target for anticancer chemotherapy: towards structure-aided drug design.
Hargrove TY, Friggeri L, Wawrzak Z, Sivakumaran S, Yazlovitskaya EM, Hiebert SW, Guengerich FP, Waterman MR, Lepesheva GI
(2016) J Lipid Res 57: 1552-63
MeSH Terms: 14-alpha Demethylase Inhibitors, Antifungal Agents, Antineoplastic Agents, Antiprotozoal Agents, Catalytic Domain, Cell Line, Tumor, Cholestadienols, Crystallography, X-Ray, Drug Design, Drug Screening Assays, Antitumor, Humans, Hydrogen Bonding, Lanosterol, Models, Molecular, Protein Binding, Protein Conformation, alpha-Helical, Sterol 14-Demethylase
Show Abstract · Added April 6, 2017
Rapidly multiplying cancer cells synthesize greater amounts of cholesterol to build their membranes. Cholesterol-lowering drugs (statins) are currently in clinical trials for anticancer chemotherapy. However, given at higher doses, statins cause serious side effects by inhibiting the formation of other biologically important molecules derived from mevalonate. Sterol 14α-demethylase (CYP51), which acts 10 steps downstream, is potentially a more specific drug target because this portion of the pathway is fully committed to cholesterol production. However, screening a variety of commercial and experimental inhibitors of microbial CYP51 orthologs revealed that most of them (including all clinical antifungals) weakly inhibit human CYP51 activity, even if they display high apparent spectral binding affinity. Only one relatively potent compound, (R)-N-(1-(3,4'-difluorobiphenyl-4-yl)-2-(1H-imidazol-1-yl)ethyl)-4-(5-phenyl-1,3,4-oxadiazol-2-yl)benzamide (VFV), was identified. VFV has been further tested in cellular experiments and found to decrease proliferation of different cancer cell types. The crystal structures of human CYP51-VFV complexes (2.0 and 2.5 Å) both display a 2:1 inhibitor/enzyme stoichiometry, provide molecular insights regarding a broader substrate profile, faster catalysis, and weaker susceptibility of human CYP51 to inhibition, and outline directions for the development of more potent inhibitors.
Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.
0 Communities
3 Members
0 Resources
17 MeSH Terms
Biosynthetic Mechanism of Lanosterol: Cyclization.
Chen N, Wang S, Smentek L, Hess BA, Wu R
(2015) Angew Chem Int Ed Engl 54: 8693-6
MeSH Terms: Biosynthetic Pathways, Cyclization, Humans, Intramolecular Transferases, Kinetics, Lanosterol, Models, Molecular, Squalene, Thermodynamics
Show Abstract · Added February 15, 2016
The remarkable cyclization mechanism of the formation of the 6-6-6-5 tetracyclic lanosterol (a key triterpenoid intermediate in the biosynthesis of cholesterol) from the acyclic 2,3-oxidosqualene catalyzed by oxidosqualene cyclase (OSC) has stimulated the interest of chemists and biologists for over a half century. Herein, the elaborate, state-of-the-art two-dimensional (2D) QM/MM MD simulations have clearly shown that the cyclization of the A-C rings involves a nearly concerted, but highly asynchronous cyclization, to yield a stable intermediate with "6-6-5" rings followed by the ring expansion of the C-ring concomitant with the formation of the D-ring to yield the "6-6-6-5" protosterol cation. The calculated reaction barrier of the rate-limiting step (≈22 kcal mol(-1)) is comparable to the experimental kinetic results. Furthermore all previous experimental mutagenic evidence is highly consistent with the identified reaction mechanism.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
0 Communities
1 Members
0 Resources
9 MeSH Terms
Structural complex of sterol 14α-demethylase (CYP51) with 14α-methylenecyclopropyl-Delta7-24, 25-dihydrolanosterol.
Hargrove TY, Wawrzak Z, Liu J, Waterman MR, Nes WD, Lepesheva GI
(2012) J Lipid Res 53: 311-20
MeSH Terms: 14-alpha Demethylase Inhibitors, Binding Sites, Crystallography, X-Ray, Dose-Response Relationship, Drug, Enzyme Activation, Lanosterol, Models, Molecular, Mutation, Protein Conformation, Sterol 14-Demethylase, Trypanocidal Agents, Trypanosoma brucei brucei
Show Abstract · Added February 12, 2015
Sterol 14α-demethylase (CYP51) that catalyzes the removal of the 14α-methyl group from the sterol nucleus is an essential enzyme in sterol biosynthesis, a primary target for clinical and agricultural antifungal azoles and an emerging target for antitrypanosomal chemotherapy. Here, we present the crystal structure of Trypanosoma (T) brucei CYP51 in complex with the substrate analog 14α-methylenecyclopropyl-Δ7-24,25-dihydrolanosterol (MCP). This sterol binds tightly to all protozoan CYP51s and acts as a competitive inhibitor of F105-containing (plant-like) T. brucei and Leishmania (L) infantum orthologs, but it has a much stronger, mechanism-based inhibitory effect on I105-containing (animal/fungi-like) T. cruzi CYP51. Depicting substrate orientation in the conserved CYP51 binding cavity, the complex specifies the roles of the contact amino acid residues and sheds new light on CYP51 substrate specificity. It also provides an explanation for the effect of MCP on T. cruzi CYP51. Comparison with the ligand-free and azole-bound structures supports the notion of structural rigidity as the characteristic feature of the CYP51 substrate binding cavity, confirming the enzyme as an excellent candidate for structure-directed design of new drugs, including mechanism-based substrate analog inhibitors.
0 Communities
1 Members
0 Resources
12 MeSH Terms
Lanosterol metabolism and sterol regulatory element binding protein (SREBP) expression in male germ cell maturation.
Fon Tacer K, Kalanj-Bognar S, Waterman MR, Rozman D
(2003) J Steroid Biochem Mol Biol 85: 429-38
MeSH Terms: Animals, CCAAT-Enhancer-Binding Proteins, DNA-Binding Proteins, Gene Expression Regulation, Lanosterol, Liver, Male, Mice, Mice, Inbred CBA, RNA, Messenger, Reverse Transcriptase Polymerase Chain Reaction, Sexual Maturation, Spermatogenesis, Sterol Regulatory Element Binding Protein 1, Sterol Regulatory Element Binding Protein 2, Testis, Transcription Factors
Show Abstract · Added February 12, 2015
Expression of genes involved in cholesterol biosynthesis in male germ cells is insensitive to the negative cholesterol feedback regulation, in contrast to cholesterol level-sensitive/sterol regulatory element binding protein (SREBP)-dependent gene regulation in somatic cells. The role of sterol regulatory element binding proteins in spermatogenic cells was an enigma until recently, when a soluble, 55kDa cholesterol-insensitive form of SREBP2 (SREBP2gc) was discovered [Mol. Cell. Endocrinol. 22 (2002) 8478], being translated from a germ cell-specific SREBP2 mRNA. Our RT-PCR results also show that SREBP2 as well as SREBP1c mRNAs are detectable in prepubertal and postpubertal male germ cells while SREBP1a is not detected. Surprisingly, three SREBP2 immunoreactive proteins (72, 63 and 55kDa), that are not present in mouse liver nuclei, reside in testis nuclei of prepubertal and adult mice. The 55kDa protein is likely SREBP2gc, the other two isoforms are novel. HPLC measurements in liver and testes of fasted prepubertal and postpubertal mice showed no significant difference in cholesterol level. However, FF-MAS and lanosterol/testis-meiosis activating sterol (T-MAS) intermediates that are detectable mainly in testes, increase in fasted postpubertal mice which coincides well with the elevated level of 68kDa SREBP2. Similar to SREBP2gc, the two novel SREBP2 immunoreactive proteins seem to be insensitive to the level of cholesterol.
0 Communities
1 Members
0 Resources
17 MeSH Terms
Substrate recognition sites in 14alpha-sterol demethylase from comparative analysis of amino acid sequences and X-ray structure of Mycobacterium tuberculosis CYP51.
Podust LM, Stojan J, Poulos TL, Waterman MR
(2001) J Inorg Biochem 87: 227-35
MeSH Terms: Amino Acid Sequence, Binding Sites, Crystallography, X-Ray, Cytochrome P-450 Enzyme System, Lanosterol, Models, Molecular, Molecular Sequence Data, Mycobacterium tuberculosis, Oxidoreductases, Sequence Alignment, Sterol 14-Demethylase, Substrate Specificity
Show Abstract · Added February 12, 2015
The crystal structure of 14alpha-sterol demethylase from Mycobacterium tuberculosis (MTCYP51) [Proc. Natl. Acad. Sci. USA 98 (2001) 3068-3073] provides a template for analysis of eukaryotic orthologs which constitute the CYP51 family of cytochrome P450 proteins. Putative substrate recognition sites (SRSs) were identified in MTCYP51 based on the X-ray structures and have been compared with SRSs predicted based on Gotoh's analysis [J. Biol. Chem. 267 (1992) 83-90]. While Gotoh's SRS-4, 5, and 6 contribute in formation of the putative MTCYP51 substrate binding site, SRS-2 and 3 likely do not exist in MTCYP51. SRS-1, as part of the open BC loop, in the conformation found in the crystal can provide only limited contacts with the sterol. However, its role in substrate binding might dramatically increase if the loop closes in response to substrate binding. Thus, while the notion of SRSs has been very useful in leading to our current understanding of P450 structure and function, their identification by sequence alignment between distant P450 families will not necessarily be a good predictor of residues associated with substrate binding. Localization of CYP51 mutation hotspots in Candida albicans azole resistant isolates was analyzed with respect to SRSs. These mutations are found to be outside of the putative substrate interacting sites indicating the preservation of the protein active site under the pressure of azole treatment. Since the mutations residing outside the putative CYP51 active side can profoundly influence ligand binding within the active site, perhaps they provide insight into the basis of evolutionary changes which have occurred leading to different P450s.
0 Communities
1 Members
0 Resources
12 MeSH Terms
Retention of the label during the conversion of [3-3H] squalene into (3S)-2,3-oxidosqualene catalyzed by mammalian squalene oxidase.
Boutaud O, Ceruti M, Cattel L, Schuber F
(1995) Biochem Biophys Res Commun 208: 42-7
MeSH Terms: Animals, Biotransformation, Lanosterol, Microsomes, Liver, NADPH-Ferrihemoprotein Reductase, Oxygenases, Radioisotope Dilution Technique, Squalene, Squalene Monooxygenase, Swine, Tritium
Show Abstract · Added March 27, 2014
Squalene epoxidase is the only known flavoprotein that catalyzes the epoxidation of an olefin. In order to test the possibility of a catalytic non-heme metal-based mechanism, the conversion of chemically synthesized [3-3H]squalene into [3H]2,3-oxidosqualene, by partially purified pig liver squalene epoxidase, was studied. No exchange of the labeled hydrogen could be observed, ruling out a mechanism involving, e.g., an iron carbene type species at C-3.
0 Communities
1 Members
0 Resources
11 MeSH Terms