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Chen N, Cao W, Yuan Y, Wang Y, Zhang X, Chen Y, Yiasmin MN, Tristanto NA, Hua X. Recent advancements in mogrosides: A review on biological activities, synthetic biology, and applications in the food industry. Food Chem 2024; 449:139277. [PMID: 38608607 DOI: 10.1016/j.foodchem.2024.139277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/14/2024]
Abstract
Mogrosides are low-calorie, biologically active sweeteners that face high production costs due to strict cultivation requirements and the low yield of monk fruit. The rapid advancement in synthetic biology holds the potential to overcome this challenge. This review presents mogrosides exhibiting antioxidant, anti-inflammatory, anti-cancer, anti-diabetic, and liver protective activities, with their efficacy in diabetes treatment surpassing that of Xiaoke pills (a Chinese diabetes medication). It also discusses the latest elucidated biosynthesis pathways of mogrosides, highlighting the challenges and research gaps in this field. The critical and most challenging step in this pathway is the transformation of mogrol into a variety of mogrosides by different UDP-glucosyltransferases (UGTs), primarily hindered by the poor substrate selectivity, product specificity, and low catalytic efficiency of current UGTs. Finally, the applications of mogrosides in the current food industry and the challenges they face are discussed.
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Affiliation(s)
- Nuo Chen
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Weichao Cao
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yuying Yuan
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yuhang Wang
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Xijia Zhang
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
| | - Yujie Chen
- Jiangsu Stevia Biotechnology Co., Ltd, Wuxi 214122, China
| | - Mst Nushrat Yiasmin
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | | | - Xiao Hua
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
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Coates HW, Capell-Hattam IM, Olzomer EM, Du X, Farrell R, Yang H, Byrne FL, Brown AJ. Hypoxia truncates and constitutively activates the key cholesterol synthesis enzyme squalene monooxygenase. eLife 2023; 12:82843. [PMID: 36655986 PMCID: PMC9851614 DOI: 10.7554/elife.82843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/13/2022] [Indexed: 01/20/2023] Open
Abstract
Cholesterol synthesis is both energy- and oxygen-intensive, yet relatively little is known of the regulatory effects of hypoxia on pathway enzymes. We previously showed that the rate-limiting and first oxygen-dependent enzyme of the committed cholesterol synthesis pathway, squalene monooxygenase (SM), can undergo partial proteasomal degradation that renders it constitutively active. Here, we show hypoxia is a physiological trigger for this truncation, which occurs through a two-part mechanism: (1) increased targeting of SM to the proteasome via stabilization of the E3 ubiquitin ligase MARCHF6 and (2) accumulation of the SM substrate, squalene, which impedes the complete degradation of SM and liberates its truncated form. This preserves SM activity and downstream pathway flux during hypoxia. These results uncover a feedforward mechanism that allows SM to accommodate fluctuating substrate levels and may contribute to its widely reported oncogenic properties.
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Affiliation(s)
- Hudson W Coates
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | | | - Ellen M Olzomer
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Rhonda Farrell
- Prince of Wales Private HospitalRandwickAustralia
- Chris O’Brien LifehouseCamperdownAustralia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
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Tellurium: A Rare Element with Influence on Prokaryotic and Eukaryotic Biological Systems. Int J Mol Sci 2021; 22:ijms22115924. [PMID: 34072929 PMCID: PMC8199023 DOI: 10.3390/ijms22115924] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 11/16/2022] Open
Abstract
Metalloid tellurium is characterized as a chemical element belonging to the chalcogen group without known biological function. However, its compounds, especially the oxyanions, exert numerous negative effects on both prokaryotic and eukaryotic organisms. Recent evidence suggests that increasing environmental pollution with tellurium has a causal link to autoimmune, neurodegenerative and oncological diseases. In this review, we provide an overview about the current knowledge on the mechanisms of tellurium compounds' toxicity in bacteria and humans and we summarise the various ways organisms cope and detoxify these compounds. Over the last decades, several gene clusters conferring resistance to tellurium compounds have been identified in a variety of bacterial species and strains. These genetic determinants exhibit great genetic and functional diversity. Besides the existence of specific resistance mechanisms, tellurium and its toxic compounds interact with molecular systems, mediating general detoxification and mitigation of oxidative stress. We also discuss the similarity of tellurium and selenium biochemistry and the impact of their compounds on humans.
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Pandreka A, Chaya PS, Kumar A, Aarthy T, Mulani FA, Bhagyashree DD, B SH, Jennifer C, Ponnusamy S, Nagegowda D, Thulasiram HV. Limonoid biosynthesis 3: Functional characterization of crucial genes involved in neem limonoid biosynthesis. PHYTOCHEMISTRY 2021; 184:112669. [PMID: 33524856 DOI: 10.1016/j.phytochem.2021.112669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 01/09/2021] [Accepted: 01/09/2021] [Indexed: 06/12/2023]
Abstract
Neem (Azadirachta indica L.) is well known for its medicinal, agricultural, and pesticidal applications since ages. The secondary metabolites, limonoids, confer these biological properties, wherein over 150 different limonoids have been reported from neem. To understand limonoid biosynthesis, we analyzed tissue-specific (kernel, pericarp, leaves, and flower) transcriptome that resulted in the identification of one farnesyl diphosphate synthase (AiFDS), one squalene synthase (AiSQS), three squalene epoxidases (AiSQE1, AiSQE2, and AiSQE3), two triterpene synthases (AiTTS1 and AiTTS2), cycloartenol synthase (AiCAS), two cytochrome P450 reductases, and ten cytochrome P450 systems. Comparative tissue-expression analysis indicated that AiFDS, AiSQS, AiSQE3, and AiTTS1 are expressed higher in the kernel than in the other tissues. Heterologously expressed recombinant AiTTS1 produced tirucalla-7,24-dien-3β-ol as the sole product. Expression profile data, phylogeny with triterpene synthases from Meliaceae and Rutaceae families, real-time PCR of different tissues, and transient transformation revealed the involvement of tirucalla-7,24-dien-3β-ol synthase (AiTTS1) in limonoid biosynthesis. Further, mutagenesis studies of AiTTS1 indicated that Y125 and F260 are probably involved in stabilization of dammarenyl cation. A 2.6-fold increase in production of tirucalla-7,24-dien-3β-ol was observed when AiSQE1 was co-expressed with mutant AiTTS1 in a yeast system. Furthermore, we functionally characterized the highly expressed cytochrome P450 reductases and cycloartenol synthase. This study helps in further analysis and identification of genes involved in limonoid biosynthesis in Meliaceae/Rutaceae and their production in a metabolically tractable heterologous system.
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Affiliation(s)
- Avinash Pandreka
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India; CSIR-Institute of Genomics and Integrative Biology, Mall Road, New Delhi, 110007, India.
| | - Patil S Chaya
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Ashish Kumar
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Thiagarayaselvam Aarthy
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Fayaj A Mulani
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Date D Bhagyashree
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Shilpashree H B
- CSIR-Central Institute of Medicinal and Aromatic Plants, Bengaluru, 560065, India.
| | - Cheruvathur Jennifer
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Sudha Ponnusamy
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.
| | - Dinesh Nagegowda
- CSIR-Central Institute of Medicinal and Aromatic Plants, Bengaluru, 560065, India.
| | - Hirekodathakallu V Thulasiram
- Chemical Biology Unit, Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India; CSIR-Institute of Genomics and Integrative Biology, Mall Road, New Delhi, 110007, India.
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Chua NK, Coates HW, Brown AJ. Squalene monooxygenase: a journey to the heart of cholesterol synthesis. Prog Lipid Res 2020; 79:101033. [DOI: 10.1016/j.plipres.2020.101033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
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Upadhyay S, Jeena GS, Kumar S, Shukla RK. Asparagus racemosus bZIP transcription factor-regulated squalene epoxidase (ArSQE) promotes germination and abiotic stress tolerance in transgenic tobacco. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 290:110291. [PMID: 31779892 DOI: 10.1016/j.plantsci.2019.110291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 08/27/2019] [Accepted: 09/26/2019] [Indexed: 06/10/2023]
Abstract
A. racemosus is a rich source of pharmacologically active steroidal saponins. Most of the studies are related to its chemistry and pharmacology, but the pathway involved in the biosynthesis of steroidal saponin is not much emphasized. Squalene epoxidase acts as a rate-limiting enzyme in this biosynthesis. In this study, we have selected root specific squalene epoxidase ArSQE from A. racemosus for its characterization. ArSQE was able to complement ergosterol auxotrophy in erg1 yeast mutants. Mutants were sensitive to the antifungal drug terbinafine, whereas ArSQE complementation made them tolerant to the same drug. ArSQE plays a significant role in early germination in transgenic tobacco. The transgenic tobacco seedlings overexpressing ArSQE were tolerant to terbinafine and abiotic stress. Expression analysis of transcripts in ArSQE transgenic lines suggests that it mostly affects ABA, GA, stress, and sterol related functions in transgenic tobacco. Further, root specific MeJA responsive A. racemosus bZIP transcription factors (TFs), ArTGA1 and ArTGA2, were identified that bind to MeJA responsive cis-element present in the promoter region of ArSQE. Characterization of ArSQE of A. racemosus provides new information about its regulation through MeJA responsive bZIP TF along with its role in the development and abiotic stress response in transgenic tobacco.
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Affiliation(s)
- Swati Upadhyay
- Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India
| | - Gajendra Singh Jeena
- Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India
| | - Sunil Kumar
- Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India
| | - Rakesh Kumar Shukla
- Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India.
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Improving lupeol production in yeast by recruiting pathway genes from different organisms. Sci Rep 2019; 9:2992. [PMID: 30816209 PMCID: PMC6395594 DOI: 10.1038/s41598-019-39497-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/03/2019] [Indexed: 01/13/2023] Open
Abstract
Lupeol is a pentacyclic triterpene that shows a variety of pharmacological properties. Compared to engineering the production of sesquiterpenes and diterpenes, it is much more challenging to engineer the biosynthesis of triterpenes in microbial platforms. This study showed our efforts on engineering the triterpene pathway in Escherichia coli and Saccharomyces cerevisiae cells by recruiting the codon-optimized three lupeol pathway genes from different organisms. By comparing their activities with their respective counterparts, the squalene synthase from Thermosynechococcus elongates (tSQS), the squalene epoxidase from Rattus norvegicus (rSE) and the lupeol synthase from Olea europaea (OeLUP) were introduced into E. coli BL21(DE3), a break-through from zero was observed for lupeol biosynthesis in a prokaryotic host. We also assessed the lupeol pathway under two different yeast backgrounds-WAT11 and EPY300, and have found that the engineered strains based on EPY300, named ECHHOe, processed the best lupeol-producing ability with the maximum lupeol titer being 200.1 mg l−1 at 30 °C in a 72 h-flask culture, which so far was the highest amount of lupeol obtained by a microbial system and provides a basis for further industrial application of lupeol in the future.
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The shape of human squalene epoxidase expands the arsenal against cancer. Nat Commun 2019; 10:888. [PMID: 30792392 PMCID: PMC6384927 DOI: 10.1038/s41467-019-08866-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 02/04/2019] [Indexed: 01/31/2023] Open
Abstract
Squalene epoxidase (also known as squalene monooxygenase, EC 1.14.99.7) is a key rate-limiting enzyme in cholesterol biosynthesis. Anil Padyana and colleagues report the long awaited structure of human squalene epoxidase (SQLE). They solved the crystal structure of the catalytic domain of human SQLE alone and in complex with two similar pharmacological inhibitors and elucidate their mechanism of action. SQLE is the target of fungicides and of increasing interest in human health and disease, particularly as a new anti-cancer target. Indeed, in a companion paper, Christopher Mahoney and colleagues performed an inhibitor screen with cancer cell lines and identified SQLE as an unique vulnerability in a subset of neuroendocrine tumours, where SQLE inhibition caused a toxic accumulation of the substrate squalene. The SQLE structure will facilitate the development of improved inhibitors. Here, we comment on these two studies in the wider context of the field and discuss possible future directions.
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Padyana AK, Gross S, Jin L, Cianchetta G, Narayanaswamy R, Wang F, Wang R, Fang C, Lv X, Biller SA, Dang L, Mahoney CE, Nagaraja N, Pirman D, Sui Z, Popovici-Muller J, Smolen GA. Structure and inhibition mechanism of the catalytic domain of human squalene epoxidase. Nat Commun 2019; 10:97. [PMID: 30626872 PMCID: PMC6327030 DOI: 10.1038/s41467-018-07928-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 12/04/2018] [Indexed: 12/22/2022] Open
Abstract
Squalene epoxidase (SQLE), also known as squalene monooxygenase, catalyzes the stereospecific conversion of squalene to 2,3(S)-oxidosqualene, a key step in cholesterol biosynthesis. SQLE inhibition is targeted for the treatment of hypercholesteremia, cancer, and fungal infections. However, lack of structure-function understanding has hindered further progression of its inhibitors. We have determined the first three-dimensional high-resolution crystal structures of human SQLE catalytic domain with small molecule inhibitors (2.3 Å and 2.5 Å). Comparison with its unliganded state (3.0 Å) reveals conformational rearrangements upon inhibitor binding, thus allowing deeper interpretation of known structure-activity relationships. We use the human SQLE structure to further understand the specificity of terbinafine, an approved agent targeting fungal SQLE, and to provide the structural insights into terbinafine-resistant mutants encountered in the clinic. Collectively, these findings elucidate the structural basis for the specificity of the epoxidation reaction catalyzed by SQLE and enable further rational development of next-generation inhibitors.
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Affiliation(s)
- Anil K Padyana
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA.
| | - Stefan Gross
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
| | - Lei Jin
- Agile Biostructure Solutions Consulting, LLC, 8 Harris Ave, Wellesley, MA, 02481, USA
| | - Giovanni Cianchetta
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
- KSQ Therapeutics, 610 Main St, Cambridge, MA, 02139, USA
| | | | - Feng Wang
- Wuxi Biortus Biosciences Co. Ltd., 6 Dongsheng West Road, Jiangyin, 214437, China
| | - Rui Wang
- Wuxi Biortus Biosciences Co. Ltd., 6 Dongsheng West Road, Jiangyin, 214437, China
- Department of Stomatology, Xiamen University, 361102, Xiamen, China
| | - Cheng Fang
- Shanghai ChemPartner Co. Ltd., 998 Halei Road, 201203, Shanghai, China
| | - Xiaobing Lv
- Shanghai ChemPartner Co. Ltd., 998 Halei Road, 201203, Shanghai, China
- Sundia MediTech Company, Ltd., 917 Halei Road, 201203, Shanghai, China
| | - Scott A Biller
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
| | - Lenny Dang
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
| | | | | | - David Pirman
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
| | - Zhihua Sui
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
| | - Janeta Popovici-Muller
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
- Decibel Therapeutics, 1325 Boylston St Suite 500, Boston, MA, 02215, USA
| | - Gromoslaw A Smolen
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, MA, 02139, USA
- Celsius Therapeutics, 215 First Street, Cambridge, MA, 02142, USA
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Molecular mechanism of metabolic NAD(P)H-dependent electron-transfer systems: The role of redox cofactors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:233-258. [PMID: 30419202 DOI: 10.1016/j.bbabio.2018.11.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 10/30/2018] [Accepted: 11/07/2018] [Indexed: 12/14/2022]
Abstract
NAD(P)H-dependent electron-transfer (ET) systems require three functional components: a flavin-containing NAD(P)H-dehydrogenase, one-electron carrier and metal-containing redox center. In principle, these ET systems consist of one-, two- and three-components, and the electron flux from pyridine nucleotide cofactors, NADPH or NADH to final electron acceptor follows a linear pathway: NAD(P)H → flavin → one-electron carrier → metal containing redox center. In each step ET is primarily controlled by one- and two-electron midpoint reduction potentials of protein-bound redox cofactors in which the redox-linked conformational changes during the catalytic cycle are required for the domain-domain interactions. These interactions play an effective ET reactions in the multi-component ET systems. The microsomal and mitochondrial cytochrome P450 (cyt P450) ET systems, nitric oxide synthase (NOS) isozymes, cytochrome b5 (cyt b5) ET systems and methionine synthase (MS) ET system include a combination of multi-domain, and their organizations display similarities as well as differences in their components. However, these ET systems are sharing of a similar mechanism. More recent structural information obtained by X-ray and cryo-electron microscopy (cryo-EM) analysis provides more detail for the mechanisms associated with multi-domain ET systems. Therefore, this review summarizes the roles of redox cofactors in the metabolic ET systems on the basis of one-electron redox potentials. In final Section, evolutionary aspects of NAD(P)H-dependent multi-domain ET systems will be discussed.
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Choudhri P, Rani M, Sangwan RS, Kumar R, Kumar A, Chhokar V. De novo sequencing, assembly and characterisation of Aloe vera transcriptome and analysis of expression profiles of genes related to saponin and anthraquinone metabolism. BMC Genomics 2018; 19:427. [PMID: 29859051 PMCID: PMC5984767 DOI: 10.1186/s12864-018-4819-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 05/22/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aloe vera is a perennial, succulent, drought-resistant plant that exhibits many pharmacological characteristics such as wound healing ability against skin burns, anti-ulcer, anti-inflammatory, anti-tumor, anti-viral, anti-hypercholesterolemic, anti-hyperglycemic, anti-asthmatic and much more. Despite great medicinal worth, little genomic information is available on Aloe vera. This study is an initiative to explore the full-scale functional genomics of Aloe vera by generating whole transcriptome sequence database, using Illumina HiSeq technology and its progressive annotation specifically with respect to the metabolic specificity of the plant. RESULTS Transcriptome sequencing of root and leaf tissue of Aloe vera was performed using Illumina paired-end sequencing technology. De novo assembly of high quality paired-end reads, resulted into 1,61,733 and 2,21,792 transcripts with mean length of 709 and 714 nucleotides for root and leaf respectively. The non-redundant transcripts were clustered using CD-HIT-EST, yielding a total of 1,13,063 and 1,41,310 unigenes for root and leaf respectively. A total of 6114 and 6527 CDS for root and leaf tissue were enriched into 24 different biological pathway categories using KEGG pathway database. DGE profile prepared by calculating FPKM values was analyzed for differential expression of specific gene encoding enzymes involved in secondary metabolite biosynthesis. Sixteen putative genes related to saponin, lignin, anthraquinone, and carotenoid biosynthesis were selected for quantitative expression by real-time PCR. DGE as well as qRT PCR expression analysis represented up-regulation of secondary metabolic genes in root as compared to leaf. Furthermore maximum number of genes was found to be up-regulated after the induction of methyl jasmonate, which stipulates the association of secondary metabolite synthesis with the plant's defense mechanism during stress. Various transcription factors including bHLH, NAC, MYB were identified by searching predicted CDS against PlantTFdb. CONCLUSIONS This is the first transcriptome database of Aloe vera and can be potentially utilized to characterize the genes involved in the biosynthesis of important secondary metabolites, metabolic regulation, signal transduction mechanism, understanding function of a particular gene in the biology and physiology of plant of this species as well as other species of Aloe genus.
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Affiliation(s)
- Pragati Choudhri
- Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001 India
| | - Muniya Rani
- Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001 India
| | - Rajender S. Sangwan
- Centre of Innovative and Applied Bioprocessing (CIAB), (A National Institute under Department of Biotechnology, Govt. of India), Sector-81 (Knowledge City), Manauli P.O., S.A.S. Nagar, Mohali, Punjab 140306 India
| | - Ravinder Kumar
- Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001 India
| | - Anil Kumar
- Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001 India
| | - Vinod Chhokar
- Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001 India
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Wei JH, Yin X, Welander PV. Sterol Synthesis in Diverse Bacteria. Front Microbiol 2016; 7:990. [PMID: 27446030 PMCID: PMC4919349 DOI: 10.3389/fmicb.2016.00990] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/09/2016] [Indexed: 11/13/2022] Open
Abstract
Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria produced demethylated and saturated sterol products even though they lacked homologs of the eukaryotic proteins required for these modifications emphasizing that several aspects of bacterial sterol synthesis are still completely unknown.
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Affiliation(s)
| | | | - Paula V. Welander
- Department of Earth System Science, Stanford UniversityStanford, CA, USA
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Haines JD, Fulton DL, Richard S, Almazan G. p38 Mitogen-Activated Protein Kinase Pathway Regulates Genes during Proliferation and Differentiation in Oligodendrocytes. PLoS One 2015; 10:e0145843. [PMID: 26714323 PMCID: PMC4699908 DOI: 10.1371/journal.pone.0145843] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 12/09/2015] [Indexed: 01/06/2023] Open
Abstract
We have previously shown that p38 mitogen-activated protein kinase (p38 MAPK) is important for oligodendrocyte (OLG) differentiation and myelination. However, the precise cellular mechanisms by which p38 regulates OLG differentiation remain largely unknown. To determine whether p38 functions in part through transcriptional events in regulating OLG identity, we performed microarray analysis on differentiating oligodendrocyte progenitors (OLPs) treated with a p38 inhibitor. Consistent with a role in OLG differentiation, pharmacological inhibition of p38 down-regulated the transcription of genes that are involved in myelin biogenesis, transcriptional control and cell cycle. Proliferation assays showed that OLPs treated with the p38 inhibitor retained a proliferative capacity which could be induced upon application of mitogens demonstrating that after two days of p38-inhibition OLGs remained poised to continue mitosis. Together, our results suggest that the p38 pathway regulates gene transcription which can coordinate OLG differentiation. Our microarray dataset will provide a useful resource for future studies investigating the molecular mechanisms by which p38 regulates oligodendrocyte differentiation and myelination.
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Affiliation(s)
- Jeffery D. Haines
- Department of Pharmacology and Therapeutics, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec, Canada, H3G 1Y6
| | - Debra L. Fulton
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 University St, Montreal, Quebec, Canada, H3A 2B4
| | - Stephane Richard
- Terry Fox Molecular Oncology Group, Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, and Departments of Oncology and Medicine, McGill University, Montreal, Quebec, Canada, H3T 1E2
| | - Guillermina Almazan
- Department of Pharmacology and Therapeutics, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec, Canada, H3G 1Y6
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 University St, Montreal, Quebec, Canada, H3A 2B4
- * E-mail:
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Dhar N, Razdan S, Rana S, Bhat WW, Vishwakarma R, Lattoo SK. A Decade of Molecular Understanding of Withanolide Biosynthesis and In vitro Studies in Withania somnifera (L.) Dunal: Prospects and Perspectives for Pathway Engineering. FRONTIERS IN PLANT SCIENCE 2015; 6:1031. [PMID: 26640469 PMCID: PMC4661287 DOI: 10.3389/fpls.2015.01031] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/06/2015] [Indexed: 05/16/2023]
Abstract
Withania somnifera, a multipurpose medicinal plant is a rich reservoir of pharmaceutically active triterpenoids that are steroidal lactones known as withanolides. Though the plant has been well-characterized in terms of phytochemical profiles as well as pharmaceutical activities, limited attempts have been made to decipher the biosynthetic route and identification of key regulatory genes involved in withanolide biosynthesis. This scenario limits biotechnological interventions for enhanced production of bioactive compounds. Nevertheless, recent emergent trends vis-à-vis, the exploration of genomic, transcriptomic, proteomic, metabolomics, and in vitro studies have opened new vistas regarding pathway engineering of withanolide production. During recent years, various strategic pathway genes have been characterized with significant amount of regulatory studies which allude toward development of molecular circuitries for production of key intermediates or end products in heterologous hosts. Another pivotal aspect covering redirection of metabolic flux for channelizing the precursor pool toward enhanced withanolide production has also been attained by deciphering decisive branch point(s) as robust targets for pathway modulation. With these perspectives, the current review provides a detailed overview of various studies undertaken by the authors and collated literature related to molecular and in vitro approaches employed in W. somnifera for understanding various molecular network interactions in entirety.
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Affiliation(s)
- Niha Dhar
- Plant Biotechnology, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
| | - Sumeer Razdan
- Plant Biotechnology, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
| | - Satiander Rana
- Plant Biotechnology, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
| | - Wajid W Bhat
- Plant Biotechnology, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
| | - Ram Vishwakarma
- Medicinal Chemistry, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
| | - Surrinder K Lattoo
- Plant Biotechnology, CSIR - Indian Institute of Integrative Medicine Jammu Tawi, India
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15
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Pinto JT, Cooper AJL. From cholesterogenesis to steroidogenesis: role of riboflavin and flavoenzymes in the biosynthesis of vitamin D. Adv Nutr 2014; 5:144-63. [PMID: 24618756 PMCID: PMC3951797 DOI: 10.3945/an.113.005181] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Flavin-dependent monooxygenases and oxidoreductases are located at critical branch points in the biosynthesis and metabolism of cholesterol and vitamin D. These flavoproteins function as obligatory intermediates that accept 2 electrons from NAD(P)H with subsequent 1-electron transfers to a variety of cytochrome P450 (CYP) heme proteins within the mitochondria matrix (type I) and the (microsomal) endoplasmic reticulum (type II). The mode of electron transfer in these systems differs slightly in the number and form of the flavin prosthetic moiety. In the type I mitochondrial system, FAD-adrenodoxin reductase interfaces with adrenodoxin before electron transfer to CYP heme proteins. In the microsomal type II system, a diflavin (FAD/FMN)-dependent cytochrome P450 oxidoreductase [NAD(P)H-cytochrome P450 reductase (CPR)] donates electrons to a multitude of heme oxygenases. Both flavoenzyme complexes exhibit a commonality of function with all CYP enzymes and are crucial for maintaining a balance of cholesterol and vitamin D metabolites. Deficits in riboflavin availability, imbalances in the intracellular ratio of FAD to FMN, and mutations that affect flavin binding domains and/or interactions with client proteins result in marked structural alterations within the skeletal and central nervous systems similar to those of disorders (inborn errors) in the biosynthetic pathways that lead to cholesterol, steroid hormones, and vitamin D and their metabolites. Studies of riboflavin deficiency during embryonic development demonstrate congenital malformations similar to those associated with genetic alterations of the flavoenzymes in these pathways. Overall, a deeper understanding of the role of riboflavin in these pathways may prove essential to targeted therapeutic designs aimed at cholesterol and vitamin D metabolism.
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16
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Huijbers MME, Montersino S, Westphal AH, Tischler D, van Berkel WJH. Flavin dependent monooxygenases. Arch Biochem Biophys 2013; 544:2-17. [PMID: 24361254 DOI: 10.1016/j.abb.2013.12.005] [Citation(s) in RCA: 364] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 11/29/2022]
Abstract
Flavin-dependent monooxygenases catalyze a wide variety of chemo-, regio- and enantioselective oxygenation reactions. As such, they are involved in key biological processes ranging from catabolism, detoxification and biosynthesis, to light emission and axon guidance. Based on fold and function, flavin-dependent monooxygenases can be distributed into eight groups. Groups A and B comprise enzymes that rely on NAD(P)H as external electron donor. Groups C-F are two-protein systems, composed of a monooxygenase and a flavin reductase. Groups G and H comprise internal monooxygenases that reduce the flavin cofactor through substrate oxidation. Recently, many new flavin-dependent monooxygenases have been discovered. In addition to posing basic enzymological questions, these proteins attract attention of pharmaceutical and fine-chemical industries, given their importance as regio- and enantioselective biocatalysts. In this review we present an update of the classification of flavin-dependent monooxygenases and summarize the latest advances in our understanding of their catalytic and structural properties.
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Affiliation(s)
- Mieke M E Huijbers
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Stefania Montersino
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Adrie H Westphal
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Dirk Tischler
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands; Interdisciplinary Ecological Center, TU Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
| | - Willem J H van Berkel
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
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Razdan S, Bhat WW, Rana S, Dhar N, Lattoo SK, Dhar RS, Vishwakarma RA. Molecular characterization and promoter analysis of squalene epoxidase gene from Withania somnifera (L.) Dunal. Mol Biol Rep 2012; 40:905-16. [PMID: 23065254 DOI: 10.1007/s11033-012-2131-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 10/03/2012] [Indexed: 11/29/2022]
Abstract
Withania somnifera is a rich reservoir of pharmaceutically active steroidal lactones known as withanolides. The plant is well characterized in terms of its chemistry and pharmacology, but very little is known about the pathway involved in the biosynthesis of withanolides. The present investigation describes the cloning, characterization and expression of squalene epoxidase (SE) gene from W. somnifera. SE (SQE; EC. 1.14.99.7) is one of the rate limiting enzymes in the biosynthesis of triterpenoids, catalyzing the stereospecific epoxidation of squalene to 2,3-oxidosqualene. A full length SE gene (WsSQE) of 1,956 bp was cloned which contained an open reading frame of 1,596 bp, encoding a protein of 531 amino acids with a predicted molecular mass of 57.67 kDa and theoretical PI of 8.48. Full length WsSQE was cloned into pGEX4T-2 vector and expressed in E.coli. Phylogenetic analysis indicated a significant evolutionary relatedness of WsSQE with squalene epoxidases of other plant species and the degree of relatedness with deduced amino acid sequences showed a significant correlation with different plant species. Using genome walking approach, a promoter sequence of 513 bp of WsSQE was isolated which revealed several key cis-regulatory elements known to be involved in various biotic and abiotic plant stresses. Comparative expression analysis of tissue specific WsSQE done by quantitative-PCR demonstrated the highest transcript levels in leaves, as compared to stalk and root tissues. This is the first report of cloning and bacterial expression of SE from W. somnifera and may be of significant interest to understand the regulatory role of SE in the biosynthesis of withanolides.
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Affiliation(s)
- Sumeer Razdan
- Plant Biotechnology, Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu Tawi, 180001, India
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18
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Belter A, Skupinska M, Giel-Pietraszuk M, Grabarkiewicz T, Rychlewski L, Barciszewski J. Squalene monooxygenase – a target for hypercholesterolemic therapy. Biol Chem 2011; 392:1053-75. [DOI: 10.1515/bc.2011.195] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes’ inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.
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Belter A, Skupinska M, Giel-Pietraszuk M, Grabarkiewicz T, Rychlewski L, Barciszewski J. Squalene monooxygenase - a target for hypercholesterolemic therapy. Biol Chem 2011. [PMID: 22050222 DOI: 10.1515/bc-2011-195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes' inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.
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Affiliation(s)
- Agnieszka Belter
- Institute of Bioorganic Chemistry, Polish Academy of Science, Noskowskiego 12/14, 61-704 Poznan, Poland
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21
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Ba LA, Döring M, Jamier V, Jacob C. Tellurium: an element with great biological potency and potential. Org Biomol Chem 2010; 8:4203-16. [PMID: 20714663 DOI: 10.1039/c0ob00086h] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Tellurium has long appeared as a nearly 'forgotten' element in Biology, with most studies focusing on tellurite, tellurate and a handful of organic tellurides. During the last decade, several discoveries have fuelled a renewed interest in this element. Bioincorporation of telluromethionine provides a new approach to add heavy atoms to selected sites in proteins. Cadmium telluride (CdTe) nanoparticles are fluorescent and may be used as quantum dots in imaging and diagnosis. The antibiotic properties of tellurite, long known yet almost forgotten, have attracted renewed interest, especially since the biochemical mechanisms of tellurium cytotoxicity are beginning to emerge. The close chemical relationship between tellurium and sulfur also transcends into in vitro and in vivo situations and provides new impetus for the development of enzyme inhibitors and redox modulators, some of which may be of interest in the field of antibiotics and anticancer drug design.
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Affiliation(s)
- Lalla Aicha Ba
- Division of Bioorganic Chemistry, School of Pharmacy, Saarland University, PO Box 151150, D-66123, Saarbruecken, Germany
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Godio RP, Fouces R, Martín JF. A Squalene Epoxidase Is Involved in Biosynthesis of Both the Antitumor Compound Clavaric Acid and Sterols in the Basidiomycete H. sublateritium. ACTA ACUST UNITED AC 2007; 14:1334-46. [DOI: 10.1016/j.chembiol.2007.10.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 10/16/2007] [Accepted: 10/23/2007] [Indexed: 12/01/2022]
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The Flexibility of the Non-Conservative Region at the C Terminus of d-Hydantoinase from Pseudomonas putida YZ-26 is Extremely Limited. Appl Biochem Biotechnol 2007; 144:237-47. [DOI: 10.1007/s12010-007-8004-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Rasbery JM, Shan H, LeClair RJ, Norman M, Matsuda SPT, Bartel B. Arabidopsis thaliana squalene epoxidase 1 is essential for root and seed development. J Biol Chem 2007; 282:17002-13. [PMID: 17426032 DOI: 10.1074/jbc.m611831200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Squalene epoxidase converts squalene into oxidosqualene, the precursor of all known angiosperm cyclic triterpenoids, which include membrane sterols, brassinosteroid phytohormones, and non-steroidal triterpenoids. In this work, we have identified six putative Arabidopsis squalene epoxidase (SQE) enzymes and used heterologous expression in yeast to demonstrate that three of these enzymes, SQE1, SQE2, and SQE3, can epoxidize squalene. We isolated and characterized Arabidopsis sqe1 mutants and discovered severe developmental defects, including reduced root and hypocotyl elongation. Adult sqe1-3 and sqe1-4 plants have diminished stature and produce inviable seeds. The sqe1-3 mutant accumulates squalene, consistent with a block in the triterpenoid biosynthetic pathway. Therefore, SQE1 function is necessary for normal plant development, and the five SQE-like genes remaining in this mutant are not fully redundant with SQE1.
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Affiliation(s)
- Jeanne M Rasbery
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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