Browse
Submit Data
Databases
API
Help

Dataset Information

19 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

An Unexpected Oxidosqualene Cyclase Active Site Architecture in the Iris tectorum Multifunctional α-Amyrin Synthase.

ABSTRACT: Ordered polycyclization catalyzed by oxidosqualene synthases (OSCs) morph a common linear precursor into structurally complex and diverse triterpene scaffolds with varied bioactivities. We identified three OSCs from Iris tectorum. ItOSC2 is a rare multifunctional α-amyrin synthase. Sequence comparisons, site-directed mutagenesis and multiscale simulations revealed that three spatially clustered residues, Y531/L256/L258 form an unusual Y-LL triad at the active site, replacing the highly conserved W-xY triad occurring in other amyrin synthases. The discovery of this unprecedented active site architecture in ItOSC2 underscores the plasticity of terpene cyclase catalytic mechanisms and opens new avenues for protein engineering towards custom designed OSCs.

SUBMITTER: Wu S

PROVIDER: S-EPMC8297885 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Iris tectorum

Project description:Iris tectorum overview

| PRJNA738219 | ENA

Molecular Docking and Molecular Dynamics Studies on Selective Synthesis of α-Amyrin and β-Amyrin by Oxidosqualene Cyclases from Ilex Asprella.

Project description:Amyrins are the immediate precursors of many pharmaceutically important pentacyclic triterpenoids. Although various amyrin synthases have been identified, little is known about the relationship between protein structures and the constituent and content of the products. IaAS1 and IaAS2 identified from Ilex asprella in our previous work belong to multifunctional oxidosqualene cyclases and can produce α-amyrin and β-amyrin at different ratios. More than 80% of total production of IaAS1 is α-amyrin; while IaAS2 mainly produces β-amyrin with a yield of 95%. Here, we present a molecular modeling approach to explore the underlying mechanism for selective synthesis. The structures of IaAS1 and IaAS2 were constructed by homology modeling, and were evaluated by Ramachandran Plot and Verify 3D program. The enzyme-product conformations generated by molecular docking indicated that ASP484 residue plays an important role in the catalytic process; and TRP611 residue of IaAS2 had interaction with β-amyrin through π-σ interaction. MM/GBSA binding free energy calculations and free energy decomposition after 50 ns molecular dynamics simulations were performed. The binding affinity between the main product and corresponding enzyme was higher than that of the by-product. Conserved amino acid residues such as TRP257; TYR259; PHE47; TRP534; TRP612; and TYR728 for IaAS1 (TRP257; TYR259; PHE473; TRP533; TRP611; and TYR727 for IaAS2) had strong interactions with both products. GLN450 and LYS372 had negative contribution to binding affinity between α-amyrin or β-amyrin and IaAS1. LYS372 and ARG261 had strong repulsive effects for the binding of α-amyrin with IaAS2. The importance of Lys372 and TRP612 of IaAS1, and Lys372 and TRP611 of IaAS2, for synthesizing amyrins were confirmed by site-directed mutagenesis. The different patterns of residue-product interactions is the cause for the difference in the yields of two products.

| S-EPMC6678101 | biostudies-literature

The complete chloroplast genome sequence of <i>Iris tectorum</i>.

Project description:The complete chloroplast genome sequence of Iris tectorum Maximowicz, assembled with Illumina NovaSeq 6000 system platform sequencing data, was reported. The total length of the chloroplast genome of I. tectorum is 153,253 bp and its GC content is 37.89%. The complete chloroplast genome has four distinct parts a large single copy region (82,833 bp), a small single copy region (18,562 bp), and a pair of inverted repeats (25,929 bp). The chloroplast genome includes 86 protein-coding genes, 8 rRNAs and 38 tRNAs genes. A phylogenetic tree showed that I. tectorum is close to Iris missouriensis.

| S-EPMC8567906 | biostudies-literature

Synthesis of arborane triterpenols by a bacterial oxidosqualene cyclase.

Project description:Cyclic triterpenoids are a broad class of polycyclic lipids produced by bacteria and eukaryotes. They are biologically relevant for their roles in cellular physiology, including membrane structure and function, and biochemically relevant for their exquisite enzymatic cyclization mechanism. Cyclic triterpenoids are also geobiologically significant as they are readily preserved in sediments and are used as biomarkers for ancient life throughout Earth's history. Isoarborinol is one such triterpenoid whose only known biological sources are certain angiosperms and whose diagenetic derivatives (arboranes) are often used as indicators of terrestrial input into aquatic environments. However, the occurrence of arborane biomarkers in Permian and Triassic sediments, which predates the accepted origin of angiosperms, suggests that microbial sources of these lipids may also exist. In this study, we identify two isoarborinol-like lipids, eudoraenol and adriaticol, produced by the aerobic marine heterotrophic bacterium Eudoraea adriatica Phylogenetic analysis demonstrates that the E. adriatica eudoraenol synthase is an oxidosqualene cyclase homologous to bacterial lanosterol synthases and distinct from plant triterpenoid synthases. Using an Escherichia coli heterologous sterol expression system, we demonstrate that substitution of four amino acid residues in a bacterial lanosterol synthase enabled synthesis of pentacyclic arborinols in addition to tetracyclic sterols. This variant provides valuable mechanistic insight into triterpenoid synthesis and reveals diagnostic amino acid residues to differentiate between sterol and arborinol synthases in genomic and metagenomic datasets. Our data suggest that there may be additional bacterial arborinol producers in marine and freshwater environments that could expand our understanding of these geologically informative lipids.

| S-EPMC5240688 | biostudies-literature

Characterization of the channel constriction allowing the access of the substrate to the active site of yeast oxidosqualene cyclase.

Project description:In oxidosqualene cyclases (OSCs), an enzyme which has been extensively studied as a target for hypocholesterolemic or antifungal drugs, a lipophilic channel connects the surface of the protein with the active site cavity. Active site and channel are separated by a narrow constriction operating as a mobile gate for the substrate passage. In Saccharomyces cerevisiae OSC, two aminoacidic residues of the channel/constriction apparatus, Ala525 and Glu526, were previously showed as critical for maintaining the enzyme functionality. In this work sixteen novel mutants, each bearing a substitution at or around the channel constrictions, were tested for their enzymatic activity. Modelling studies showed that the most functionality-lowering substitutions deeply alter the H-bond network involving the channel/constriction apparatus. A rotation of Tyr239 is proposed as part of the mechanism permitting the access of the substrate to the active site. The inhibition of OSC by squalene was used as a tool for understanding whether the residues under study are involved in a pre-catalytic selection and docking of the substrate oxidosqualene.

| S-EPMC3141018 | biostudies-literature

Oxidosqualene cyclase targeting compound in Leishmania

Project description:Overexpression library screen - Oxidosqualene cyclase targeting compound in Leishmania donovani

| PRJEB37256 | ENA

Oxidosqualene cyclase targeting compound in Leishmania

Project description:Whole genome sequencing of resistant lines - Oxidosqualene cyclase targeting compound in Leishmania donovani

| PRJEB37435 | ENA

?-Amyrin synthase from Conyza blinii expressed in Saccharomyces cerevisiae.

Project description:Conyza blinii H.Lév. is a widely used medicinal herb in southwestern China. The main pharmacological components of C. blinii are a class of oleanane-type pentacyclic triterpene glycosides known as conyzasaponins, which are thought to be synthesized from ?-amyrin. However, no genes involved in the conyzasaponin pathway have previously been identified. Here, we identify an oxidosqualene cyclase (OSC), a ?-amyrin synthase, which mediates cyclization of 2,3-oxidosqualene to yield ?-amyrin. Ten OSC sequences were isolated from C. blinii transcript tags. Phylogenetic analysis was used to select the tag Cb18076 as the putative ?-amyrin synthase, named Cb?AS. The open reading frame of Cb?AS is 2286 bp and encodes 761 amino acids. Its mature protein contains the highly conserved motifs (QXXXGXW/DCTAE) of OSCs and (MWCYCR) of ?-amyrin synthases. Transcription of Cb?AS was upregulated 4-24 h after treatment of the seedlings of the C. blinii cultivar with methyl jasmonate. Furthermore, expression of Cb?AS in Saccharomyces cerevisiae successfully yielded ?-amyrin. The chemical structures and concentrations of ?-amyrin were confirmed by GC-MS/MS. The target yeast ultimately produced 4.432 mg·L-1 ?-amyrin. Thus, Cb?AS is an OSC involved in conyzasaponin biosynthesis.

| S-EPMC5623702 | biostudies-literature

Plant oxidosqualene metabolism: cycloartenol synthase-dependent sterol biosynthesis in Nicotiana benthamiana.

Project description:The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9?,19-cyclolanost-24-en-3?-ol) and not lanosterol (lanosta-8,24-dien-3?-ol), as it was shown in the late sixties. However, plant genome mining over the last years revealed the general presence of lanosterol synthases encoding sequences (LAS1) in the oxidosqualene cyclase repertoire, in addition to cycloartenol synthases (CAS1) and to non-steroidal triterpene synthases that contribute to the metabolic diversity of C30H50O compounds on earth. Furthermore, plant LAS1 proteins have been unambiguously identified by peptidic signatures and by their capacity to complement the yeast lanosterol synthase deficiency. A dual pathway for the synthesis of sterols through lanosterol and cycloartenol was reported in the model Arabidopsis thaliana, though the contribution of a lanosterol pathway to the production of 24-alkyl-?(5)-sterols was quite marginal (Ohyama et al. (2009) PNAS 106, 725). To investigate further the physiological relevance of CAS1 and LAS1 genes in plants, we have silenced their expression in Nicotiana benthamiana. We used virus induced gene silencing (VIGS) based on gene specific sequences from a Nicotiana tabacum CAS1 or derived from the solgenomics initiative (http://solgenomics.net/) to challenge the respective roles of CAS1 and LAS1. In this report, we show a CAS1-specific functional sterol pathway in engineered yeast, and a strict dependence on CAS1 of tobacco sterol biosynthesis.

| S-EPMC4208727 | biostudies-literature

Multiple unbiased approaches identify oxidosqualene cyclase as the molecular target of a promising anti-leishmanial.

Project description:Phenotypic screening identified a benzothiophene compound with activity against Leishmania donovani, the causative agent of visceral leishmaniasis. Using multiple orthogonal approaches, oxidosqualene cyclase (OSC), a key enzyme of sterol biosynthesis, was identified as the target of this racemic compound and its enantiomers. Whole genome sequencing and screening of a genome-wide overexpression library confirmed that OSC gene amplification is associated with resistance to compound 1. Introduction of an ectopic copy of the OSC gene into wild-type cells reduced susceptibility to these compounds confirming the role of this enzyme in resistance. Biochemical analyses demonstrated the accumulation of the substrate of OSC and depletion of its product in compound (S)-1-treated-promastigotes and cell-free membrane preparations, respectively. Thermal proteome profiling confirmed that compound (S)-1 binds directly to OSC. Finally, modeling and docking studies identified key interactions between compound (S)-1 and the LdOSC active site. Strategies to improve the potency for this promising anti-leishmanial are proposed.

| S-EPMC8153249 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data