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Anteghini M, Santos VAMD, Saccenti E. PortPred: Exploiting deep learning embeddings of amino acid sequences for the identification of transporter proteins and their substrates. J Cell Biochem 2023; 124:1803-1824. [PMID: 37877557 DOI: 10.1002/jcb.30490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/26/2023]
Abstract
The physiology of every living cell is regulated at some level by transporter proteins which constitute a relevant portion of membrane-bound proteins and are involved in the movement of ions, small and macromolecules across bio-membranes. The importance of transporter proteins is unquestionable. The prediction and study of previously unknown transporters can lead to the discovery of new biological pathways, drugs and treatments. Here we present PortPred, a tool to accurately identify transporter proteins and their substrate starting from the protein amino acid sequence. PortPred successfully combines pre-trained deep learning-based protein embeddings and machine learning classification approaches and outperforms other state-of-the-art methods. In addition, we present a comparison of the most promising protein sequence embeddings (Unirep, SeqVec, ProteinBERT, ESM-1b) and their performances for this specific task.
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Affiliation(s)
- Marco Anteghini
- LifeGlimmer GmbH, Berlin, Germany
- Department of Systems and Synthetic Biology, Wageningen University & Research, Wageningen WE, The Netherlands
- Department of Visual and Data-Centric Computing, Zuse Institute Berlin, Berlin, Germany
| | - Vitor Ap Martins Dos Santos
- LifeGlimmer GmbH, Berlin, Germany
- Department of Bioprocess Engineering, Wageningen University & Research, Wageningen WE, The Netherlands
| | - Edoardo Saccenti
- Department of Systems and Synthetic Biology, Wageningen University & Research, Wageningen WE, The Netherlands
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2
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Islam Z, Kumar P. Inhibitors of riboflavin biosynthetic pathway enzymes as potential antibacterial drugs. Front Mol Biosci 2023; 10:1228763. [PMID: 37496776 PMCID: PMC10366380 DOI: 10.3389/fmolb.2023.1228763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/03/2023] [Indexed: 07/28/2023] Open
Abstract
Multiple drug resistance is the main obstacle in the treatment of bacterial diseases. Resistance against antibiotics demands the exploration of new antimicrobial drug targets. A variety of in silico and genetic approaches show that the enzymes of the riboflavin biosynthetic pathway are crucial for the survival of bacteria. This pathway is absent in humans thus enzymes of the riboflavin biosynthetic pathway are emerging drug targets for resistant pathogenic bacterial strains. Exploring the structural details, their mechanism of action, intermediate elucidation, and interaction analysis would help in designing suitable inhibitors of these enzymes. The riboflavin biosynthetic pathway consists of seven distinct enzymes, namely, 3,4-dihydroxy-2-butanone 4-phosphate synthase, GTP cyclohydrolase II, pyrimidine deaminase/reductase, phosphatase, lumazine synthase, and riboflavin synthase. The present review summarizes the research work that has been carried out on these enzymes in terms of their structures, active site architectures, and molecular mechanism of catalysis. This review also walks through small molecule inhibitors that have been developed against several of these enzymes.
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Affiliation(s)
- Zeyaul Islam
- Qatar Biomedical Research Institute (QBRI), Qatar Foundation, Hamad Bin Khalifa University, Doha, Qatar
| | - Pankaj Kumar
- Department of Biochemistry, Jamia Hamdard, New Delhi, India
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3
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Nagar N, Saxena H, Pathak A, Mishra A, Poluri KM. A review on structural mechanisms of protein-persistent organic pollutant (POP) interactions. CHEMOSPHERE 2023; 332:138877. [PMID: 37164191 DOI: 10.1016/j.chemosphere.2023.138877] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 04/20/2023] [Accepted: 05/06/2023] [Indexed: 05/12/2023]
Abstract
With the advent of the industrial revolution, the accumulation of persistent organic pollutants (POPs) in the environment has become ubiquitous. POPs are halogen-containing organic molecules that accumulate, and remain in the environment for a long time, thus causing toxic effects in living organisms. POPs exhibit a high affinity towards biological macromolecules such as nucleic acids, proteins and lipids, causing genotoxicity and impairment of homeostasis in living organisms. Proteins are essential members of the biological assembly, as they stipulate all necessary processes for the survival of an organism. Owing to their stereochemical features, POPs and their metabolites form energetically favourable complexes with proteins, as supported by biological and dose-dependent toxicological studies. Although individual studies have reported the biological aspects of protein-POP interactions, no comprehensive study summarizing the structural mechanisms, thermodynamics and kinetics of protein-POP complexes is available. The current review identifies and classifies protein-POP interaction according to the structural and functional basis of proteins into five major protein targets, including digestive and other enzymes, serum proteins, transcription factors, transporters, and G-protein coupled receptors. Further, analysis detailing the molecular interactions and structural mechanism evidenced that H-bonds, van der Waals, and hydrophobic interactions essentially mediate the formation of protein-POP complexes. Moreover, interaction of POPs alters the protein conformation through kinetic and thermodynamic processes like competitive inhibition and allostery to modulate the cellular signalling processes, resulting in various pathological conditions such as cancers and inflammations. In summary, the review provides a comprehensive insight into the critical structural/molecular aspects of protein-POP interactions.
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Affiliation(s)
- Nupur Nagar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Harshi Saxena
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Aakanksha Pathak
- Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur, 342011, Rajasthan, India
| | - Krishna Mohan Poluri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India; Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
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Di Micco S, Lauro G, Bifulco G. Extensive Molecular Dynamics Simulations Disclosed the Stability of mPGES-1 Enzyme and the Structural Role of Glutathione (GSH) Cofactor. Mol Inform 2022; 41:e2200140. [PMID: 36075865 PMCID: PMC10078397 DOI: 10.1002/minf.202200140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/08/2022] [Indexed: 01/05/2023]
Abstract
A deep in silico investigation of various microsomal prostaglandin E2 synthase-1 (mPGES-1) protein systems is here reported using molecular dynamics (MD) simulations. Firstly, eight different proteins models (Models A-H) were built, starting from the active enzyme trimer system (Model A), namely that bound to three glutathione (GSH) cofactor molecules, and then gradually removing the GSHs (Models B-H), simulating each of them for 100 ns in explicit solvent. The analysis of the obtained data disclosed the structural role of GSH in the chemical architecture of mPGES-1 enzyme, thus suggesting the unlikely displacement of this cofactor, in accordance with experimentally determined protein structures co-complexed with small molecule inhibitors. Afterwards, Model A was submitted to microsecond-scale molecular dynamics simulation (total simulation time=10 μs), in order to shed light about the dynamical behaviour of this enzyme at atomic level and to obtain further structural features and protein function information. We confirmed the structural stability of the enzyme machinery, observing a conformational rigidity of the protein, with a backbone RMSD of ∼3 Å along the simulation time, and highlighting the strong active contribution of GSH molecules due to their active role in packing the protein chains through a tight binding at monomer interfaces. Furthermore, the focused analysis on R73 residue disclosed its role in solvent exchange events, probably excluding its function as route for GSH to enter towards the endoplasmic reticulum membrane, in line with the recently reported function of cap domain residues F44-D66 as gatekeeper for GSH entrance into catalytic site.
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Affiliation(s)
- Simone Di Micco
- European Biomedical Research Institute of Salerno (EBRIS), via Salvatore De Renzi 50, 84125, Salerno, Italy
| | - Gianluigi Lauro
- Dipartimento di Farmacia, University degli Studi di Salerno, via Giovanni Paolo II 132, 84084, Fisciano (SA), Italy
| | - Giuseppe Bifulco
- Dipartimento di Farmacia, University degli Studi di Salerno, via Giovanni Paolo II 132, 84084, Fisciano (SA), Italy
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Chen Y, Xu C, Yang H, Liu Z, Zhang Z, Yan R, Zhu D. L-Arginine enhanced perylenequinone production in the endophytic fungus Shiraia sp. Slf14(w) via NO signaling pathway. Appl Microbiol Biotechnol 2022; 106:2619-2636. [PMID: 35291023 DOI: 10.1007/s00253-022-11877-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/28/2022] [Accepted: 03/06/2022] [Indexed: 11/26/2022]
Abstract
Perylenequinones (PQ) are natural polyketides used as anti-microbial, -cancers, and -viral photodynamic therapy agents. Herein, the effects of L-arginine (Arg) on PQ biosynthesis of Shiraia sp. Slf14(w) and the underlying molecular mechanism were investigated. The total content of PQ reached 817.64 ± 72.53 mg/L under optimal conditions of Arg addition, indicating a 30.52-fold improvement over controls. Comparative transcriptome analysis demonstrated that Arg supplement promoted PQ precursors biosynthesis of Slf14(w) by upregulating the expression of critical genes associated with the glycolysis pathway, and acetyl-CoA and malonyl-CoA synthesis. By downregulating the expression of genes related to the glyoxylate cycle pathway and succinate dehydrogenase, more acetyl-CoA flow into the formation of PQ. Arg supplement upregulated the putative biosynthetic gene clusters for PQ and activated the transporter proteins (MFS and ABC) for exudation of PQ. Further studies showed that Arg increased the gene transcription levels of nitric oxide synthase (NOS) and nitrate reductase (NR), and activated NOS and NR, thus promoting the formation of nitric oxide (NO). A supplement of NO donor sodium nitroprusside (SNP) also confirmed that NO triggered promoted biosynthesis and efflux of PQ. PQ production stimulated by Arg or/and SNP can be significantly inhibited upon the addition of NO scavenger carboxy-PTIO, NOS inhibitor Nω-nitro-L-arginine, or soluble guanylate cyclase inhibitor NS-2028. These results showed that Arg-derived NO, as a signaling molecule, is involved in the biosynthesis and regulation of PQ in Slf14(W) through the NO-cGMP-PKG signaling pathway. Our results provide a valuable strategy for large-scale PQ production and contribute to further understanding of NO signaling in the fungal metabolite biosynthesis. KEY POINTS: • PQ production of Shiraia sp. Slf14(w) was significantly improved by L-arginine addition. • Arginine-derived NO was firstly reported to be involved in the biosynthesis and regulation of PQ. • The NO-cGMP-PKG signaling pathway was proposed for the first time to participate in PQ biosynthesis.
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Affiliation(s)
- Yunni Chen
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
- Key Laboratory of Bioprocess Engineering of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Chenglong Xu
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
| | - Huilin Yang
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
| | - Zhenying Liu
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
- Key Laboratory of Bioprocess Engineering of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China
| | - Zhibin Zhang
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
| | - Riming Yan
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China
| | - Du Zhu
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, Jiangxi Normal University, Nanchang, 330022, China.
- Key Laboratory of Bioprocess Engineering of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China.
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An Uninvited Seat at the Dinner Table: How Apicomplexan Parasites Scavenge Nutrients from the Host. Microorganisms 2021; 9:microorganisms9122592. [PMID: 34946193 PMCID: PMC8707601 DOI: 10.3390/microorganisms9122592] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022] Open
Abstract
Obligate intracellular parasites have evolved a remarkable assortment of strategies to scavenge nutrients from the host cells they parasitize. Most apicomplexans form a parasitophorous vacuole (PV) within the invaded cell, a replicative niche within which they survive and multiply. As well as providing a physical barrier against host cell defense mechanisms, the PV membrane (PVM) is also an important site of nutrient uptake that is essential for the parasites to sustain their metabolism. This means nutrients in the extracellular milieu are separated from parasite metabolic machinery by three different membranes, the host plasma membrane, the PVM, and the parasite plasma membrane (PPM). In order to facilitate nutrient transport from the extracellular environment into the parasite itself, transporters on the host cell membrane of invaded cells can be modified by secreted and exported parasite proteins to maximize uptake of key substrates to meet their metabolic demand. To overcome the second barrier, the PVM, apicomplexan parasites secrete proteins contained in the dense granules that remodel the vacuole and make the membrane permissive to important nutrients. This bulk flow of host nutrients is followed by a more selective uptake of substrates at the PPM that is operated by specific transporters of this third barrier. In this review, we recapitulate and compare the strategies developed by Apicomplexa to scavenge nutrients from their hosts, with particular emphasis on transporters at the parasite plasma membrane and vacuolar solute transporters on the parasite intracellular digestive organelle.
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Khosla N, Thayil SM, Kaur R, Kesavan AK. MSMEG_3955 from Mycobacterium smegmatis is a FMN bounded homotrimeric NAD(P)H:Flavin mononucleotide (FMN) oxidoreductase. BMC Microbiol 2021; 21:319. [PMID: 34798816 PMCID: PMC8605562 DOI: 10.1186/s12866-021-02330-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 09/27/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Tuberculosis (TB) remains an important public health problem since it is the major cause of elevated morbidity and mortality globally. Previous works have shown that Mycobacterium tuberculosis (Mtb); the prime causative agent of the deadly disease has dormancy survival regulator (DosR) regulon, a two-component regulatory system which controls the transcription of more than 50 genes. However, the structure and detailed functions of these DosR regulated genes are largely undetermined. Out of many DosR regulon genes, Rv3131 gets up regulated in hypoxic conditions and was believed to encode for a nitroreductase flavoprotein. The utilization of mycobacteria-specific model systems has greatly added to our understanding of the molecular mechanisms involved in the life cycle and pathogenesis of Mtb. RESULTS In this study the non-pathogenic mycobacterial model organism Mycobacterium smegmatis (Msmeg) was used to reveal the structure and function of MSMEG_3955; which is a homologue of Rv3131 from Mtb. Using chromatography and spectroscopy techniques it was revealed that cofactor flavin mononucleotide (FMN) was bound to flavoprotein MSMEG_3955. Consistent with the homology modelling predictions, Circular Dichroism (CD) analysis indicated that the MSMEG_3955 is composed of 39.3% α-helix and 24.9% β-pleated sheets. In contrast to the current notions, the enzymatic assays performed in the present study revealed that MSMEG_3955 was not capable of reducing nitro substrates but showed NADPH dependent FMN oxidoreductase activity. Also, gel permeation chromatography, dynamic light scattering and native acidic gels showed that MSMEG_3955 exists as a homotrimer. Furthermore, the presence of NADPH dependent FMN oxidoreductase and homotrimeric existence could be an alternative function of the protein to help the bacteria survive in dormant state or may be involved in other biochemical pathways. CONCLUSION MSMEG_3955 is a FMN bound flavoprotein, which exits as a trimer under in vitro conditions. There is no disulphide linkages in between the three protomers of the homotrimer MSMEG_3955. It has a NADPH dependent FMN oxidoreductase activity.
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Affiliation(s)
- Neha Khosla
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Seema Madhumal Thayil
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Rajinder Kaur
- Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Anup Kumar Kesavan
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
- Current Address: Department of Biotechnology & Microbiology, Kannur University, Dr. E.K. Janaki Ammal Campus, Palayad, Thalassery, Kannur, Kerala, India.
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Evans JD, Krause S, Feringa BL. Cooperative and synchronized rotation in motorized porous frameworks: impact on local and global transport properties of confined fluids. Faraday Discuss 2021; 225:286-300. [DOI: 10.1039/d0fd00016g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Simulations reveal the influence of rotating molecular motors and the importance of orientation and directionality for altering the transport properties of fluids. This has outlined that motors with specific rotation can generate directed diffusion.
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Affiliation(s)
- Jack D. Evans
- Department of Inorganic Chemistry
- Technische Universität Dresden
- 01062 Dresden
- Germany
| | - Simon Krause
- Centre for Systems Chemistry
- Stratingh Institute for Chemistry
- University of Groningen
- Groningen
- The Netherlands
| | - Ben L. Feringa
- Centre for Systems Chemistry
- Stratingh Institute for Chemistry
- University of Groningen
- Groningen
- The Netherlands
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9
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Molecular Elucidation of Riboflavin Production and Regulation in Candida albicans, toward a Novel Antifungal Drug Target. mSphere 2020; 5:5/4/e00714-20. [PMID: 32759338 PMCID: PMC7407072 DOI: 10.1128/msphere.00714-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Candida albicans is an important fungal pathogen causing common superficial infections as well as invasive diseases with an extremely high morbidity and mortality. Antifungal therapies are limited in efficiency and availability. In this research, we describe the regulation of riboflavin production in C. albicans. Since riboflavin biosynthesis is essential to this organism, we can appreciate that targeting it would be a promising new strategy to combat these fungal infections. We provide evidence that one particular enzyme in the production process, CaRib1, would be most promising as an antifungal drug target, as it plays a central role in regulation and proves to be essential in a mouse model of systemic infection. Candida albicans is a major cause of fungal infections, both superficial and invasive. The economic costs as well as consequences for patient welfare are substantial. Only a few treatment options are available due to the high resemblance between fungal targets and host molecules, as both are eukaryotes. Riboflavin is a yellow pigment, also termed vitamin B2. Unlike animals, fungi can synthesize this essential component themselves, thereby leading us to appreciate that targeting riboflavin production is a promising novel strategy against fungal infections. Here, we report that the GTP cyclohydrolase encoded by C. albicansRIB1 (CaRIB1) is essential and rate-limiting for production of riboflavin in the fungal pathogen. We confirm the high potential of CaRib1 as an antifungal drug target, as its deletion completely impairs in vivo infectibility by C. albicans in model systems. Furthermore, the stimulating effect of iron deprivation and PKA activation on riboflavin production seems to involve CaRib1 and the upstream transcription factor CaSef1. Gathering insights in the synthesis mechanism of riboflavin in pathogenic fungi, like C. albicans, will allow us to design a novel strategy and specifically target this process to combat fungal infections. IMPORTANCECandida albicans is an important fungal pathogen causing common superficial infections as well as invasive diseases with an extremely high morbidity and mortality. Antifungal therapies are limited in efficiency and availability. In this research, we describe the regulation of riboflavin production in C. albicans. Since riboflavin biosynthesis is essential to this organism, we can appreciate that targeting it would be a promising new strategy to combat these fungal infections. We provide evidence that one particular enzyme in the production process, CaRib1, would be most promising as an antifungal drug target, as it plays a central role in regulation and proves to be essential in a mouse model of systemic infection.
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Kumari J, Rathore MS. Na+/K+-ATPase a Primary Membrane Transporter: An Overview and Recent Advances with Special Reference to Algae. J Membr Biol 2020; 253:191-204. [DOI: 10.1007/s00232-020-00119-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 05/02/2020] [Indexed: 12/16/2022]
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Cremers FPM, Lee W, Collin RWJ, Allikmets R. Clinical spectrum, genetic complexity and therapeutic approaches for retinal disease caused by ABCA4 mutations. Prog Retin Eye Res 2020; 79:100861. [PMID: 32278709 PMCID: PMC7544654 DOI: 10.1016/j.preteyeres.2020.100861] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/18/2022]
Abstract
The ABCA4 protein (then called a “rim protein”) was first
identified in 1978 in the rims and incisures of rod photoreceptors. The
corresponding gene, ABCA4, was cloned in 1997, and variants
were identified as the cause of autosomal recessive Stargardt disease (STGD1).
Over the next two decades, variation in ABCA4 has been
attributed to phenotypes other than the classically defined STGD1 or fundus
flavimaculatus, ranging from early onset and fast progressing cone-rod dystrophy
and retinitis pigmentosa-like phenotypes to very late onset cases of mostly mild
disease sometimes resembling, and confused with, age-related macular
degeneration. Similarly, analysis of the ABCA4 locus uncovered
a trove of genetic information, including >1200 disease-causing mutations
of varying severity, and of all types – missense, nonsense, small
deletions/insertions, and splicing affecting variants, of which many are located
deep-intronic. Altogether, this has greatly expanded our understanding of
complexity not only of the diseases caused by ABCA4 mutations,
but of all Mendelian diseases in general. This review provides an in depth
assessment of the cumulative knowledge of ABCA4-associated retinopathy –
clinical manifestations, genetic complexity, pathophysiology as well as current
and proposed therapeutic approaches.
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands.
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, 10032, USA.
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Nuamtanong S, Reamtong O, Phuphisut O, Chotsiri P, Malaithong P, Dekumyoy P, Adisakwattana P. Transcriptome and excretory-secretory proteome of infective-stage larvae of the nematode Gnathostoma spinigerum reveal potential immunodiagnostic targets for development. ACTA ACUST UNITED AC 2019; 26:34. [PMID: 31166909 PMCID: PMC6550564 DOI: 10.1051/parasite/2019033] [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: 12/18/2018] [Accepted: 05/16/2019] [Indexed: 01/02/2023]
Abstract
Background: Gnathostoma spinigerum is a harmful parasitic nematode that causes severe morbidity and mortality in humans and animals. Effective drugs and vaccines and reliable diagnostic methods are needed to prevent and control the associated diseases; however, the lack of genome, transcriptome, and proteome databases remains a major limitation. In this study, transcriptomic and secretomic analyses of advanced third-stage larvae of G. spinigerum (aL3Gs) were performed using next-generation sequencing, bioinformatics, and proteomics. Results: An analysis that incorporated transcriptome and bioinformatics data to predict excretory–secretory proteins (ESPs) classified 171 and 292 proteins into classical and non-classical secretory groups, respectively. Proteins with proteolytic (metalloprotease), cell signaling regulatory (i.e., kinases and phosphatase), and metabolic regulatory function (i.e., glucose and lipid metabolism) were significantly upregulated in the transcriptome and secretome. A two-dimensional (2D) immunomic analysis of aL3Gs-ESPs with G. spinigerum-infected human sera and related helminthiases suggested that the serine protease inhibitor (serpin) was a promising antigenic target for the further development of gnathostomiasis immunodiagnostic methods. Conclusions: The transcriptome and excretory–secretory proteome of aL3Gs can facilitate an understanding of the basic molecular biology of the parasite and identifying multiple associated factors, possibly promoting the discovery of novel drugs and vaccines. The 2D-immunomic analysis identified serpin, a protein secreted from aL3Gs, as an interesting candidate for immunodiagnosis that warrants immediate evaluation and validation.
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Affiliation(s)
- Supaporn Nuamtanong
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Onrapak Reamtong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Orawan Phuphisut
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Palang Chotsiri
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
| | - Preeyarat Malaithong
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Paron Dekumyoy
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Poom Adisakwattana
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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Schmidt L, Wielsch N, Wang D, Boland W, Burse A. Tissue-specific profiling of membrane proteins in the salicin sequestering juveniles of the herbivorous leaf beetle, Chrysomela populi. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:81-91. [PMID: 30922827 DOI: 10.1016/j.ibmb.2019.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/21/2019] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
Sequestration of plant secondary metabolites is a detoxification strategy widespread in herbivorous insects including not only storage, but also usage of these metabolites for the insects' own benefit. Larvae of the poplar leaf beetle Chrysomela populi sequester plant-derived salicin to produce the deterrent salicylaldehyde in specialized exocrine glands. To identify putative transporters involved in the sequestration process we investigated integral membrane proteins of several tissues from juvenile C. populi by using a proteomics approach. Computational analyses led to the identification of 122 transport proteins in the gut, 105 in the Malpighian tubules, 94 in the fat body and 27 in the defensive glands. Among these, primary active transporters as well as electrochemical potential-driven transporters were most abundant in all tissues, including ABC transporters (especially subfamilies B, C and G) and sugar porters as most interesting families facilitating the sequestration of plant glycosides. Whereas ABC transporters are predominantly expressed simultaneously in several tissues, sugar porters are often expressed in only one tissue, suggesting that sugar porters govern more distinct functions than members of the ABC family. The inventory of transporters presented in this study provides the base for further functional characterizations on transport processes of sequestered glycosides in insects.
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Affiliation(s)
- Lydia Schmidt
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Natalie Wielsch
- Max Planck Institute for Chemical Ecology, Research Group Mass Spectrometry/ Proteomics, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Ding Wang
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Wilhelm Boland
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany
| | - Antje Burse
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745, Jena, Germany.
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14
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Duan Şahbaz B, Birgül Iyison N. Prediction and expression analysis of G protein-coupled receptors in the laboratory stick insect, Carausius morosus. ACTA ACUST UNITED AC 2019; 43:77-88. [PMID: 30930638 PMCID: PMC6426647 DOI: 10.3906/biy-1809-27] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCRs) are 7-transmembrane proteins that transduce various extracellular signals into intracellular pathways. They are the major target of neuropeptides, which regulate the development, feeding behavior, mating behavior, circadian rhythm, and many other physiological functions of insects. In the present study, we performed RNA sequencing and de novo transcriptome assembly to uncover the GPCRs expressed in the stick insect Carausius morosus. The transcript assemblies were predicted for the presence of 7-transmembrane GPCR domains. As a result, 430 putative GPCR transcripts were obtained and 43 of these revealed full-length sequences with highly significant similarity to known GPCR sequences in the databases. Thirteen different GPCRs were chosen for tissue expression analysis. Some of these receptors, such as calcitonin, inotocin, and tyramine receptors, showed specific expression in some of the tissues. Additionally, GPCR prediction yielded a novel uncharacterized GPCR sequence, which was specifically expressed in the central nervous system and ganglia. Previously, the only information about the anatomy of the stick insect was on its gastrointestinal system. This study provides complete anatomical information about the adult insect.
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Affiliation(s)
- Burçin Duan Şahbaz
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Boğaziçi University , İstanbul , Turkey
| | - Necla Birgül Iyison
- Center for Life Sciences and Technologies, Boğaziçi University , İstanbul , Turkey.,Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Boğaziçi University , İstanbul , Turkey
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15
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Pandey V, Krishnan V, Basak N, Marathe A, Thimmegowda V, Dahuja A, Jolly M, Sachdev A. Molecular modeling and in silico characterization of GmABCC5: a phytate transporter and potential target for low-phytate crops. 3 Biotech 2018; 8:54. [PMID: 29354365 DOI: 10.1007/s13205-017-1053-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/17/2017] [Indexed: 02/06/2023] Open
Abstract
Designing low-phytate crops without affecting the developmental process in plants had led to the identification of ABCC5 gene in soybean. The GmABCC5 gene was identified and a partial gene sequence was cloned from popular Indian soybean genotype Pusa16. Conserved domains and motifs unique to ABC transporters were identified in the 30 homologous sequences retrieved by BLASTP analysis. The homologs were analyzed for their evolutionary relationship and physiochemical properties. Conserved domains, transmembrane architecture and secondary structure of GmABCC5 were predicted with the aid of computational tools. Analysis identified 53 alpha helices and 31 beta strands, predicting 60% residues in alpha conformation. A three-dimensional (3D) model for GmABCC5 was developed based on 5twv.1.B (Homo sapiens) template homology to gain better insight into its molecular mechanism of transport and sequestration. Spatio-temporal real-time PCR analysis identified mid-to-late seed developmental stages as the time window for the maximum GmABCC5 gene expression, a potential target stage for phytate reduction. Results of this study provide valuable insights into the structural and functional characteristics of GmABCC5, which may be further utilized for the development of nutritionally enriched low-phytate soybean with improved mineral bioavailability.
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Affiliation(s)
- Vanita Pandey
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
- Quality and Basic Sciences, ICAR-Indian Institute of Wheat and Barley Research, Karnal, New Delhi 132 001 India
| | - Veda Krishnan
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Nabaneeta Basak
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
- Crop Physiology and Biochemistry, ICAR-National Rice Research Institute, Cuttack, 753006 India
| | - Ashish Marathe
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Vinutha Thimmegowda
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Anil Dahuja
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Monica Jolly
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Archana Sachdev
- 1Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
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16
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Lazareva NF, Baryshok VP, Lazarev IM. Silicon-containing analogs of camptothecin as anticancer agents. Arch Pharm (Weinheim) 2017; 351. [PMID: 29239010 DOI: 10.1002/ardp.201700297] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 12/17/2022]
Abstract
The plant pentacyclic alkaloid camptothecin and its structural analogs were extensively studied. These compounds are interesting due to the antitumor activity associated with their ability to inhibit topoisomerase I in tumor cells. During the last decades of the 20th century, a large number of the silicon-containing camptothecins (silatecans) were synthesized. 7-tert-Butyldimethylsilyl-10-hydroxy-camptothecin (DB-67 or AR-67) has enhanced lipophilicity and demonstrates a antitumor activity superior to its carbon analog. To date, certain silatecans are under clinical trials and their ultimate role in cancer therapy appears promising. In this review, we present chemical methodologies for the synthesis of silicon-containing camptothecins, their chemical properties, biological activity, and results of clinical trials.
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Affiliation(s)
- Nataliya F Lazareva
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
| | - Viktor P Baryshok
- Irkutsk National Research Technical University, Irkutsk, Russian Federation
| | - Igor M Lazarev
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
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17
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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18
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Yellapu NK. Molecular Modelling, Dynamics, and Docking of Membrane Proteins. PHARMACEUTICAL SCIENCES 2017. [DOI: 10.4018/978-1-5225-1762-7.ch029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Computational tools and techniques are now most popular and promising to progress the research at rapid rate. Molecular modelling studies contribute their maximum role in wide variety of disciplines especially in proteomics and drug discovery strategies. Molecular dynamics and molecular docking algorithms are now became an essential part in daily research activities of every laboratory throughout the world. These strategies are now well established and standardised to study any specific protein of interest and drug molecule. But still there exist considerable drawbacks in a special concern with membrane proteins as the presently available tools and methods cannot be applied directly to them. Modelling, dynamics and docking studies of membrane proteins need a special care and attention as several challenges are to be crossed with an intensive care to produce a reliable result. This chapter is aimed to discuss such challenges and solutions to handle membrane proteins.
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19
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Mak L, Marcus D, Howlett A, Yarova G, Duchateau G, Klaffke W, Bender A, Glen RC. Metrabase: a cheminformatics and bioinformatics database for small molecule transporter data analysis and (Q)SAR modeling. J Cheminform 2015; 7:31. [PMID: 26106450 PMCID: PMC4477067 DOI: 10.1186/s13321-015-0083-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 06/10/2015] [Indexed: 11/17/2022] Open
Abstract
ABSTRACT Both metabolism and transport are key elements defining the bioavailability and biological activity of molecules, i.e. their adverse and therapeutic effects. Structured and high quality experimental data stored in a suitable container, such as a relational database, facilitates easy computational processing and thus allows for high quality information/knowledge to be efficiently inferred by computational analyses. Our aim was to create a freely accessible database that would provide easy access to data describing interactions between proteins involved in transport and xenobiotic metabolism and their small molecule substrates and modulators. We present Metrabase, an integrated cheminformatics and bioinformatics resource containing curated data related to human transport and metabolism of chemical compounds. Its primary content includes over 11,500 interaction records involving nearly 3,500 small molecule substrates and modulators of transport proteins and, currently to a much smaller extent, cytochrome P450 enzymes. Data was manually extracted from the published literature and supplemented with data integrated from other available resources. Metrabase version 1.0 is freely available under a CC BY-SA 4.0 license at http://www-metrabase.ch.cam.ac.uk.
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Affiliation(s)
- Lora Mak
- />The Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
- />European Molecular Biology Laboratory - European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD UK
| | - David Marcus
- />The Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
- />European Molecular Biology Laboratory - European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SD UK
| | - Andrew Howlett
- />The Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
| | - Galina Yarova
- />Unilever Research & Development, 40 Merritt Blvd, Trumbull, CT 06611 USA
| | - Guus Duchateau
- />Unilever Research & Development, Olivier van Noortlaan, 3133 AT Vlaardingen, The Netherlands
| | - Werner Klaffke
- />Unilever Research & Development, Olivier van Noortlaan, 3133 AT Vlaardingen, The Netherlands
- />Haus der Technik e.V., Hollestrasse 1, 45127 Essen, Germany
| | - Andreas Bender
- />The Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
| | - Robert C Glen
- />The Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
- />Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, SW7 2AZ London, UK
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20
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Soga N, Watanabe R, Noji H. Attolitre-sized lipid bilayer chamber array for rapid detection of single transporters. Sci Rep 2015; 5:11025. [PMID: 26052065 PMCID: PMC4458879 DOI: 10.1038/srep11025] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 05/13/2015] [Indexed: 12/31/2022] Open
Abstract
We present an attolitre-sized arrayed lipid bilayer chamber system (aL-ALBiC) for rapid and massively parallel single-molecule assay of membrane transporter activity. Because of the small reaction volume (200 aL), the aL-ALBiC performed fast detection of single transporter activity, thereby enhancing the sensitivity, throughput, and accuracy of the analysis. Thus, aL-ALBiC broadens the opportunities for single-molecule analysis of various membrane transporters and can be used in pharmaceutical applications such as drug screening.
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Affiliation(s)
- Naoki Soga
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Rikiya Watanabe
- 1] Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan [2] PRESTO, Japan Science and Technology, Bunkyo-ku, Tokyo 113-8656, Japan [3] CREST, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Hiroyuki Noji
- 1] Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan [2] CREST, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0075, Japan
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21
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Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin. Curr Genet 2015; 61:601-20. [PMID: 25862648 DOI: 10.1007/s00294-015-0486-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 03/26/2015] [Accepted: 03/28/2015] [Indexed: 01/09/2023]
Abstract
The goal of this work is to characterize membrane transporter genes in Cercospora fungi required for autoresistance to the photoactivated, active-oxygen-generating toxin cercosporin they produce for infection of host plants. Previous studies implicated a role for diverse membrane transporters in cercosporin resistance. In this study, transporters identified in a subtractive cDNA library between a Cercospora nicotianae wild type and a cercosporin-sensitive mutant were characterized, including two ABC transporters (CnATR2, CnATR3), an MFS transporter (CnMFS2), a uracil transporter, and a zinc transport protein. Phylogenetic analysis showed that only CnATR3 clustered with transporters previously characterized to be involved in cercosporin resistance. Quantitative RT-PCR analysis of gene expression under conditions of cercosporin toxicity, however, showed that only CnATR2 was upregulated, thus this gene was selected for further characterization. Transformation and expression of CnATR2 in the cercosporin-sensitive fungus Neurospora crassa significantly increased cercosporin resistance. Targeted gene disruption of CnATR2 in the wild type C. nicotianae, however, did not decrease resistance. Expression analysis of other transporters in the cnatr2 mutant under conditions of cercosporin toxicity showed significant upregulation of the cercosporin facilitator protein gene (CFP), encoding an MFS transporter previously characterized as playing an important role in cercosporin autoresistance in Cercospora species. We conclude that cercosporin autoresistance in Cercospora is mediated by multiple genes, and that the fungus compensates for mutations by up-regulation of other resistance genes. CnATR2 may be a useful gene, alone or in addition to other known resistance genes, for engineering Cercospora resistance in crop plants.
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22
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Duatti A. Molecular imaging with endogenous and exogenous ligands: The instance of antibodies, peptides, iodide and cupric ions. Nucl Med Biol 2015; 42:215-8. [DOI: 10.1016/j.nucmedbio.2014.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 11/14/2014] [Accepted: 11/15/2014] [Indexed: 02/05/2023]
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23
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Membrane transporters in salivary exosomes and microvesicles as biomarkers of systemic or oral disease. J Oral Biosci 2014. [DOI: 10.1016/j.job.2014.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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24
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Crystal structure of microsomal prostaglandin E2 synthase provides insight into diversity in the MAPEG superfamily. Proc Natl Acad Sci U S A 2013; 110:3806-11. [PMID: 23431194 DOI: 10.1073/pnas.1218504110] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Prostaglandin E2 (PGE2) is a key mediator in inflammatory response. The main source of inducible PGE2, microsomal PGE2 synthase-1 (mPGES-1), has emerged as an interesting drug target for treatment of pain. To support inhibitor design, we have determined the crystal structure of human mPGES-1 to 1.2 Å resolution. The structure reveals three well-defined active site cavities within the membrane-spanning region in each monomer interface of the trimeric structure. An important determinant of the active site cavity is a small cytosolic domain inserted between transmembrane helices I and II. This extra domain is not observed in other structures of proteins within the MAPEG (Membrane-Associated Proteins involved in Eicosanoid and Glutathione metabolism) superfamily but is likely to be present also in microsomal GST-1 based on sequence similarity. An unexpected feature of the structure is a 16-Å-deep cone-shaped cavity extending from the cytosolic side into the membrane-spanning region. We suggest a potential role for this cavity in substrate access. Based on the structure of the active site, we propose a catalytic mechanism in which serine 127 plays a key role. We have also determined the structure of mPGES-1 in complex with a glutathione-based analog, providing insight into mPGES-1 flexibility and potential for structure-based drug design.
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25
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Chan CX, Reyes-Prieto A, Bhattacharya D. Red and green algal origin of diatom membrane transporters: insights into environmental adaptation and cell evolution. PLoS One 2011; 6:e29138. [PMID: 22195008 PMCID: PMC3237598 DOI: 10.1371/journal.pone.0029138] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 11/21/2011] [Indexed: 01/06/2023] Open
Abstract
Membrane transporters (MTs) facilitate the movement of molecules between cellular compartments. The evolutionary history of these key components of eukaryote genomes remains unclear. Many photosynthetic microbial eukaryotes (e.g., diatoms, haptophytes, and dinoflagellates) appear to have undergone serial endosymbiosis and thereby recruited foreign genes through endosymbiotic/horizontal gene transfer (E/HGT). Here we used the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum as models to examine the evolutionary origin of MTs in this important group of marine primary producers. Using phylogenomics, we used 1,014 diatom MTs as query against a broadly sampled protein sequence database that includes novel genome data from the mesophilic red algae Porphyridium cruentum and Calliarthron tuberculosum, and the stramenopile Ectocarpus siliculosus. Our conservative approach resulted in 879 maximum likelihood trees of which 399 genes show a non-lineal history between diatoms and other eukaryotes and prokaryotes (at the bootstrap value ≥70%). Of the eukaryote-derived MTs, 172 (ca. 25% of 697 examined phylogenies) have members of both red/green algae as sister groups, with 103 putatively arising from green algae, 19 from red algae, and 50 have an unresolved affiliation to red and/or green algae. We used topology tests to analyze the most convincing cases of non-lineal gene history in which red and/or green algae were nested within stramenopiles. This analysis showed that ca. 6% of all trees (our most conservative estimate) support an algal origin of MTs in stramenopiles with the majority derived from green algae. Our findings demonstrate the complex evolutionary history of photosynthetic eukaryotes and indicate a reticulate origin of MT genes in diatoms. We postulate that the algal-derived MTs acquired via E/HGT provided diatoms and other related microbial eukaryotes the ability to persist under conditions of fluctuating ocean chemistry, likely contributing to their great success in marine environments.
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Affiliation(s)
- Cheong Xin Chan
- Department of Ecology, Evolution and Natural Resources and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Adrian Reyes-Prieto
- Department of Ecology, Evolution and Natural Resources and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Debashish Bhattacharya
- Department of Ecology, Evolution and Natural Resources and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
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26
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Hodgkinson S, Kaschka WP. Patterns of hydrophobicity found in the first and second transmembrane domains of solute transporters suggest a possible role in nascent protein anchoring and organization. J Bioinform Comput Biol 2011; 9:471-88. [PMID: 21776604 DOI: 10.1142/s0219720011005367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 10/15/2010] [Accepted: 11/30/2010] [Indexed: 11/18/2022]
Abstract
Solute transporters (STs) are an important subgroup of integral membrane proteins that facilitate the translocation of a diverse range of solutes such as sugars, amino acids, and neurotransmitters across cell membranes. Sequence analysis indicates that STs possess multiple stretches of hydrophobic-rich amino acids that are organized into the transmembrane domains (TMDs) of the functional protein, but exactly how the correct spatial arrangement of these domains is achieved remains a challenging problem. We hypothesized that perhaps differences in interdomain hydrophobicity might play some role in this process. To test this hypothesis, we generated a heptadic model of the alpha helix and mapped the average hydrophobicities (coaxial) and hydrophobic moments (radial) of 108 TMDs found in 9 different human ST proteins. Our results, taken together with earlier work from other groups, suggest that spatial patterns of hydrophobicity found in TMDs 1 and 2 are consistent with a role for these domains in the initial anchoring of the nascent ST protein to the endoplasmic reticulum (ER), as it emerges from the ribosome complex and perhaps in the subsequent spatial organisation of STs.
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Affiliation(s)
- Steve Hodgkinson
- Department of Psychiatry and Psychotherapy I, University Hospital Ulm, Weingartshofer Strasse 2, D-88214 Ravensburg, Germany.
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27
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Long Q, Ji L, Wang H, Xie J. Riboflavin Biosynthetic and Regulatory Factors as Potential Novel Anti-Infective Drug Targets. Chem Biol Drug Des 2010; 75:339-47. [DOI: 10.1111/j.1747-0285.2010.00946.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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28
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Kors CA, Wallace E, Davies DR, Li L, Laible PD, Nollert P. Effects of impurities on membrane-protein crystallization in different systems. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2009; 65:1062-73. [PMID: 19770503 PMCID: PMC2748966 DOI: 10.1107/s0907444909029163] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 07/22/2009] [Indexed: 11/18/2022]
Abstract
When starting a protein-crystallization project, scientists are faced with several unknowns. Amongst them are these questions: (i) is the purity of the starting material sufficient? and (ii) which type of crystallization experiment is the most promising to conduct? The difficulty in purifying active membrane-protein samples for crystallization trials and the high costs associated with producing such samples require an extremely pragmatic approach. Additionally, practical guidelines are needed to increase the efficiency of membrane-protein crystallization. In order to address these conundrums, the effects of commonly encountered impurities on various membrane-protein crystallization regimes have been investigated and it was found that the lipidic cubic phase (LCP) based crystallization methodology is more robust than crystallization in detergent environments using vapor diffusion or microbatch approaches in its ability to tolerate contamination in the forms of protein, lipid or other general membrane components. LCP-based crystallizations produced crystals of the photosynthetic reaction center (RC) of Rhodobacter sphaeroides from samples with substantial levels of residual impurities. Crystals were obtained with protein contamination levels of up to 50% and the addition of lipid material and membrane fragments to pure samples of RC had little effect on the number or on the quality of crystals obtained in LCP-based crystallization screens. If generally applicable, this tolerance for impurities may avoid the need for samples of ultrahigh purity when undertaking initial crystallization screening trials to determine preliminary crystallization conditions that can be optimized for a given target protein.
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Affiliation(s)
- Christopher A. Kors
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA
| | - Ellen Wallace
- deCODE biostructures, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Douglas R. Davies
- deCODE biostructures, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Liang Li
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Philip D. Laible
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA
| | - Peter Nollert
- deCODE biostructures, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
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29
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Aliverdieva DA, Mamaev DV, Lagutina LS. Characteristics of the succinate transport into Saccharomices cerevisiae cellsafter prolonged cold preincubation. APPL BIOCHEM MICRO+ 2009. [DOI: 10.1134/s0003683809050111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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30
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Aliverdieva DA, Mamaev DV. Molecular characteristics of transporters of C4-dicarboxylates and mechanism of translocation. J EVOL BIOCHEM PHYS+ 2009. [DOI: 10.1134/s0022093009030016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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31
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Dahl SG, Aarons L, Gundert-Remy U, Karlsson MO, Schneider YJ, Steimer JL, Trocóniz IF. Incorporating physiological and biochemical mechanisms into pharmacokinetic-pharmacodynamic models: a conceptual framework. Basic Clin Pharmacol Toxicol 2009; 106:2-12. [PMID: 19686541 DOI: 10.1111/j.1742-7843.2009.00456.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The aim of this conceptual framework paper is to contribute to the further development of the modelling of effects of drugs or toxic agents by an approach which is based on the underlying physiology and pathology of the biological processes. In general, modelling of data has the purpose (1) to describe experimental data, (2a) to reduce the amount of data resulting from an experiment, e.g. a clinical trial and (2b) to obtain the most relevant parameters, (3) to test hypotheses and (4) to make predictions within the boundaries of experimental conditions, e.g. range of doses tested (interpolation) and out of the boundaries of the experimental conditions, e.g. to extrapolate from animal data to the situation in man. Describing the drug/xenobiotic-target interaction and the chain of biological events following the interaction is the first step to build a biologically based model. This is an approach to represent the underlying biological mechanisms in qualitative and also quantitative terms, thus being inherently connected in many aspects to systems biology. As the systems biology models may contain variables in the order of hundreds connected with differential equations, it is obvious that it is in most cases not possible to assign values to the variables resulting from experimental data. Reduction techniques may be used to create a manageable model which, however, captures the biologically meaningful events in qualitative and quantitative terms. Until now, some success has been obtained by applying empirical pharmacokinetic/pharmacodynamic models which describe direct and indirect relationships between the xenobiotic molecule and the effect, including tolerance. Some of the models may have physiological components built in the structure of the model and use parameter estimates from published data. In recent years, some progress toward semi-mechanistic models has been made, examples being chemotherapy-induced myelosuppression and glucose-endogenous insulin-antidiabetic drug interactions. We see a way forward by employing approaches to bridge the gap between systems biology and physiologically based kinetic and dynamic models. To be useful for decision making, the 'bridging' model should have a well founded mechanistic basis, but being reduced to the extent that its parameters can be deduced from experimental data, however capturing the biological/clinical essential details so that meaningful predictions and extrapolations can be made.
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Affiliation(s)
- Svein G Dahl
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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Amnuaykanjanasin A, Daub ME. The ABC transporter ATR1 is necessary for efflux of the toxin cercosporin in the fungus Cercospora nicotianae. Fungal Genet Biol 2008; 46:146-58. [PMID: 19095071 DOI: 10.1016/j.fgb.2008.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 11/17/2008] [Accepted: 11/18/2008] [Indexed: 11/18/2022]
Abstract
The Cercospora nicotianae mutant deficient for the CRG1 transcription factor has marked reductions in both resistance and biosynthesis of the toxin cercosporin. We cloned and sequenced full-length copies of two genes, ATR1 and CnCFP, previously identified from a subtractive library between the wild type (WT) and a crg1 mutant. ATR1 is an ABC transporter gene and has an open reading frame (ORF) of 4368bp with one intron. CnCFP encodes a MFS transporter with homology to Cercospora kikuchii CFP, previously implicated in cercosporin export, and has an ORF of 1975bp with three introns. Disruption of ATR1 indicated atr1-null mutants had dramatic reductions in cercosporin production (25% and 20% of WT levels) in solid and liquid cultures, respectively. The ATR1 disruptants also showed moderately higher sensitivity to cercosporin. Constitutive expression of ATR1 in the crg1 mutant restored cercosporin biosynthesis and moderately increased resistance. In contrast, CnCFP overexpression in the mutant did not restore toxin production, however, it moderately enhanced toxin resistance. The results together indicate ATR1 acts as a cercosporin efflux pump in this fungus and plays a partial role in resistance.
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Blodgett DM, Graybill C, Carruthers A. Analysis of glucose transporter topology and structural dynamics. J Biol Chem 2008; 283:36416-24. [PMID: 18981181 DOI: 10.1074/jbc.m804802200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homology modeling and scanning cysteine mutagenesis studies suggest that the human glucose transport protein GLUT1 and its distant bacterial homologs LacY and GlpT share similar structures. We tested this hypothesis by mapping the accessibility of purified, reconstituted human erythrocyte GLUT1 to aqueous probes. GLUT1 contains 35 potential tryptic cleavage sites. Fourteen of 16 lysine residues and 18 of 19 arginine residues were accessible to trypsin. GLUT1 lysine residues were modified by isothiocyanates and N-hydroxysuccinimide (NHS) esters in a substrate-dependent manner. Twelve lysine residues were accessible to sulfo-NHS-LC-biotin. GLUT1 trypsinization released full-length transmembrane helix 1, cytoplasmic loop 6-7, and the long cytoplasmic C terminus from membranes. Trypsin-digested GLUT1 retained cytochalasin B and d-glucose binding capacity and released full-length transmembrane helix 8 upon cytochalasin B (but not D-glucose) binding. Transmembrane helix 8 release did not abrogate cytochalasin B binding. GLUT1 was extensively proteolyzed by alpha-chymotrypsin, which cuts putative pore-forming amphipathic alpha-helices 1, 2, 4, 7, 8, 10, and 11 at multiple sites to release transmembrane peptide fragments into the aqueous solvent. Putative scaffolding membrane helices 3, 6, 9, and 12 are strongly hydrophobic, resistant to alpha-chymotrypsin, and retained by the membrane bilayer. These observations provide experimental support for the proposed GLUT1 architecture; indicate that the proposed topology of membrane helices 5, 6, and 12 requires adjustment; and suggest that the metastable conformations of transmembrane helices 1 and 8 within the GLUT1 scaffold destabilize a sugar translocation intermediate.
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Affiliation(s)
- David M Blodgett
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Jørgensen AM, Tagmose L, Jørgensen AMM, Bøgesø KP, Peters GH. Molecular dynamics simulations of Na+/Cl(-)-dependent neurotransmitter transporters in a membrane-aqueous system. ChemMedChem 2008; 2:827-40. [PMID: 17436258 DOI: 10.1002/cmdc.200600243] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have performed molecular dynamics simulations of a homology model of the human serotonin transporter (hSERT) in a membrane environment and in complex with either the natural substrate 5-HT or the selective serotonin reuptake inhibitor escitalopram. We have also included a transporter homologue, the Aquifex aeolicus leucine transporter (LeuT), in our study to evaluate the applicability of a simple and computationally attractive membrane system. Fluctuations in LeuT extracted from simulations are in good agreement with crystallographic B factors. Furthermore, key interactions identified in the X-ray structure of LeuT are maintained throughout the simulations indicating that our simple membrane system is suitable for studying the transmembrane protein hSERT in complex with 5-HT or escitalopram. For these transporter complexes, only relatively small fluctuations are observed in the ligand-binding cleft. Specific interactions responsible for ligand recognition, are identified in the hSERT-5HT and hSERT-escitalopram complexes. Our findings are in good agreement with predictions from mutagenesis studies.
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Affiliation(s)
- Anne Marie Jørgensen
- MEMPHYS-Center for Biomembrane Physics, Department of Chemistry, Technical University of Denmark, Building 206, 2800 Kgs. Lyngby, Denmark
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Development of predictive in silico model for cyclosporine- and aureobasidin-based P-glycoprotein inhibitors employing receptor surface analysis. J Mol Graph Model 2008; 27:439-51. [PMID: 18789739 DOI: 10.1016/j.jmgm.2008.07.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Revised: 07/28/2008] [Accepted: 07/29/2008] [Indexed: 11/21/2022]
Abstract
P-glycoprotein (Pgp) is implicated in multiple drug resistance (MDR) exhibited by several types of cancer against a multitude of anticancer chemotherapeutic agents. This problem prompted several research groups to search for effective P-gp inhibitors. Cyclosporine A (CsA), aureobasidin A (AbA) and related analogues were reported to possess potent inhibitory actions against Pgp. In this work we employed receptor surface analysis (RSA) to construct two satisfactory receptor surface models (RSMs) for cyclosporine- and aureobasidin-based Pgp inhibitors. These pseudoreceptors were combined to achieve satisfactory three-dimensional quantitative structure activity relationship (3D-QSAR) for 68 different cyclosporine and aureobasidin derivatives. Upon validation against an external set of 16 randomly selected Pgp inhibitors, the optimal 3D-QSAR was found to be self-consistent and predictive (r(LOO)(2)=0.673, r(PRESS)(2)=0.600). The resulting 3D-QSAR was employed to probe the structural factors that control the inhibitory activities of cyclosporine and aureobasidin analogues against Pgp.
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36
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Abstract
Membrane transport proteins are integral membrane proteins and considered as potential drug targets. Activity assay of transport proteins is essential for developing drugs to target these proteins. Major issues related to activity assessment of transport proteins include availability of transporters, transport activity of transporters, and interactions between ligands and transporters. Researchers need to consider the physiological status of proteins (bound in lipid membranes or purified), availability and specificity of substrates, and the purpose of the activity assay (screening, identifying, or comparing substrates and inhibitors) before choosing appropriate assay strategies and techniques. Transport proteins bound in vesicular membranes can be assayed for transporting substrate across membranes by means of uptake assay or entrance counterflow assay. Alternatively, transport proteins can be assayed for interactions with ligands by using techniques such as isothermal titration calorimetry, nuclear magnetic resonance spectroscopy, or surface plasmon resonance. Other methods and techniques such as fluorometry, scintillation proximity assay, electrophysiological assay, or stopped-flow assay could also be used for activity assay of transport proteins. In this paper the major strategies and techniques for activity assessment of membrane transport proteins are reviewed.
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Affiliation(s)
- Hao Xie
- Department of Biological Science and Biotechnology, Institute of Science, Wuhan University of Technology, Wuhan 430070, China.
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Kusel JR, Oliveira FA, Todd M, Ronketti F, Lima SF, Mattos ACA, Reis KT, Coelho PMZ, Thornhill JA, Ribeiro F. The effects of drugs, ions, and poly-l-lysine on the excretory system of Schistosoma mansoni. Mem Inst Oswaldo Cruz 2008; 101 Suppl 1:293-8. [PMID: 17308785 DOI: 10.1590/s0074-02762006000900046] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Accepted: 06/26/2006] [Indexed: 11/22/2022] Open
Abstract
We have been able to label the excretory system of cercariae and all forms of schistosomula, immature and adult worms with the highly fluorescent dye resorufin. We have shown that the accumulation of the resorufin into the excretory tubules and collecting ducts of the male adult worm depends on the presence of extracellular calcium and phosphate ions. In the adult male worms, praziquantel (PZQ) prevents this accumulation in RPMI medium and disperses resorufin from tubules which have been prelabelled. Female worms and all other developmental stages are much less affected either by the presence of calcium and phosphate ions, or the disruption caused by PZQ. The male can inhibit the excretory system in paired female. Fluorescent PZQ localises in the posterior gut (intestine) region of the male adult worm, but not in the excretory system, except for the anionic carboxy fluorescein derivative of PZQ, which may be excreted by this route. All stages of the parasite can recover from damage by PZQ treatment in vitro. The excretory system is highly sensitive to damage to the surface membrane and may be involved in vesicle movement and damage repair processes. In vivo the adult parasite does not recover from PZQ treatment, but what is inhibiting recovery is unknown, but likely to be related to immune effector molecules.
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Affiliation(s)
- J R Kusel
- Glasgow University, Glasgow, Scotland.
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38
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Ravna AW, Sager G, Dahl SG, Sylte I. Membrane Transporters: Structure, Function and Targets for Drug Design. TOPICS IN MEDICINAL CHEMISTRY 2008. [DOI: 10.1007/7355_2008_023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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39
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Abstract
Translocation through the extracellular vestibule and binding of leucine in the leucine transporter (LeuT) have been studied with molecular dynamics simulations. More than 0.1 mus of all-atom molecular dynamics simulations have been performed on different combinations of LeuT, bound substrate, and bound structural Na(+) ions to describe molecular events involved in substrate binding and in the formation of the occluded state and to investigate the dynamics of this state. Three structural features are found to be directly involved in the initial steps of leucine transport: a Na(+) ion directly coordinated to leucine (Na-1), two aromatic residues closing the binding site toward the extracellular vestibule (Tyr-108 and Phe-253), and a salt bridge in the extracellular vestibule (Arg-30 and Asp-404). These features account for observed differences between simulations of LeuT with and without bound substrate and for a possible pathway for leucine binding and thereby formation of the occluded LeuT binding site.
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40
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Pánek J, Eidhammer I, Aasland R. Using hydropathy features for function prediction of membrane proteins. Mol Membr Biol 2007; 24:304-12. [PMID: 17520486 DOI: 10.1080/09687860701213884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A novel alignment-free method for computing functional similarity of membrane proteins based on features of hydropathy distribution is presented. The features of hydropathy distribution are used to represent protein families as hydropathy profiles. The profiles statistically summarize the hydropathy distribution of member proteins. The summation is made by using hydropathy features that numerically represent structurally/functionally significant portions of protein sequences. The hydropathy profiles are numerical vectors that are points in a high dimensional 'hydropathy' space. Their similarities are identified by projection of the space onto principal axes. Here, the approach is applied to the secondary transporters. The analysis using the presented approach is validated by the standard classification of the secondary transporters. The presented analysis allows for prediction of function attributes for proteins of uncharacterized families of secondary transporters. The results obtained using the presented analysis may help to characterize unknown function attributes of secondary transporters. They also show that analysis of hydropathy distribution can be used for function prediction of membrane proteins.
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Affiliation(s)
- Josef Pánek
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská, Czech Republic.
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41
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Kusel JR, Al-Adhami BH, Doenhoff MJ. The schistosome in the mammalian host: understanding the mechanisms of adaptation. Parasitology 2007; 134:1477-526. [PMID: 17572930 DOI: 10.1017/s0031182007002971] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SUMMARYIn this review, we envisage the host environment, not as a hostile one, since the schistosome thrives there, but as one in which the relationship between the two organisms consists of constant communication, through signalling mechanisms involving sense organs, surface glycocalyx, surface membrane and internal organs of the parasite, with host fluids and cells. The surface and secretions of the schistosome egg have very different properties from those of other parasite stages, but adapted for the dispersal of the eggs and for the preservation of host liver function. We draw from studies of mammalian cells and other organisms to indicate how further work might be carried out on the signalling function of the surface glycocalyx, the raft structure of the surface and existence of pores in the surface membrane, the repair of the surface membrane, the role of the membrane structure in ion channel function (including recent work on the actin cytoskeleton and calcium channels) and the possible role of P-glycoproteins in the adaptation of the parasite to its environment. We are speculative in some areas, such as the suggestions that variability in surface properties of schistosomes may relate to the existence of membrane rafts and that parasite communities may exhibit quorum sensing. This speculative approach is adopted with the hope that future work on the whole organisms and their interactions will be encouraged.
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Affiliation(s)
- J R Kusel
- Glasgow Biomedical Research Centre, University of Glasgow, Glasgow G12 8TA, UK.
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42
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Lee JH, Harvat EM, Stevens JM, Ferguson SJ, Saier MH. Evolutionary origins of members of a superfamily of integral membrane cytochrome c biogenesis proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2164-81. [PMID: 17706591 DOI: 10.1016/j.bbamem.2007.04.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2006] [Revised: 03/22/2007] [Accepted: 04/24/2007] [Indexed: 11/20/2022]
Abstract
We have analyzed the relationships of homologues of the Escherichia coli CcmC protein for probable topological features and evolutionary relationships. We present bioinformatic evidence suggesting that the integral membrane proteins CcmC (E. coli; cytochrome c biogenesis System I), CcmF (E. coli; cytochrome c biogenesis System I) and ResC (Bacillus subtilis; cytochrome c biogenesis System II) are all related. Though the molecular functions of these proteins have not been fully described, they appear to be involved in the provision of heme to c-type cytochromes, and so we have named them the putative Heme Handling Protein (HHP) family (TC #9.B.14). Members of this family exhibit 6, 8, 10, 11, 13 or 15 putative transmembrane segments (TMSs). We show that intragenic triplication of a 2 TMS element gave rise to a protein with a 6 TMS topology, exemplified by CcmC. This basic 6 TMS unit then gave rise to two distinct types of proteins with 8 TMSs, exemplified by ResC and the archaeal CcmC, and these further underwent fusional or insertional events yielding proteins with 10, 11 and 13 TMSs (ResC homologues) as well as 15 TMSs (CcmF homologues). Specific evolutionary pathways taken are proposed. This work provides the first evidence for the pathway of appearance of distantly related proteins required for post-translational maturation of c-type cytochromes in bacteria, plants, protozoans and archaea.
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Affiliation(s)
- Jong-Hoon Lee
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
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43
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Aliverdieva DA, Mamaev DV, Bondarenko DI, Sholtz KF. Topography of the active site of the Saccharomyces cerevisiae plasmalemmal dicarboxylate transporter studied using lipophilic derivatives of its substrates. BIOCHEMISTRY (MOSCOW) 2007; 72:264-74. [PMID: 17447879 DOI: 10.1134/s0006297907030030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
2-Alkylmalonates and O-acyl-L-malates have been found to competitively inhibit the dicarboxylate transporter of Saccharomyces cerevisiae cells, and the substrate derivatives chosen did not penetrate across the plasmalemma under the experiment conditions. Probing of the active site of this transporter has revealed a large lipophilic area stretching between the 0.72 to 2.5 nm from the substrate-binding site. Itaconate inhibited the transport fivefold more effectively than L-malate. This suggests the existence of a hydrophobic region immediately near the dicarboxylate-binding site (to 0.72 nm). The yeast plasmalemmal transporter was different from the rat liver mitochondrial dicarboxylate transporter. An area with variable lipophilicity adjoining the substrate-binding site has been revealed in the latter by a similar method. This area is mainly hydrophobic at distances up to 1.76 nm from the binding site and is separated by a hydrophilic region from 0.38 to 0.88 nm. Fumarate but not maleate competitively inhibited succinate transport into the S. cerevisiae cells. It is suggested that the plasmalemmal transporter binds the substrate in the trans-conformation. The prospects of the proposed approach for scanning lipophilic profiles of channels of different transporters are discussed.
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Affiliation(s)
- D A Aliverdieva
- Caspian Institute of Biological Resources, Dagestan Research Center, Russian Academy of Sciences, Makhachkala, Russia
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44
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Ravna AW. Three-dimensional models of neurotransmitter transporters and their interactions with cocaine and S-citalopram. World J Biol Psychiatry 2006; 7:99-109. [PMID: 16684682 DOI: 10.1080/15622970500402144] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Drugs that act on the human serotonin transporter (hSERT), human dopamine transporter (hDAT) and human noradrenaline transporter (hNET) are important in antidepressant treatment and well known in drug abuse. The investigation of their molecular mechanisms of action is very useful for designing new ligands with a therapeutic potential. The detailed three-dimensional molecular structure of any monoamine transporter is not known, but the three-dimensional electron density projection map of Escherichia coli Na+/H+ antiporter (NhaA) has provided structural basis for constructing models of such transporters using molecular modelling techniques. Three-dimensional models of these drug targets give insight into their structure, mechanisms and drug interactions. In these molecular modelling studies, an Escherichia coli NhaA model was first constructed based on its three-dimensional electron density projection map and experimental studies on NhaA and the Escherichia coli lactose permease symporter (Lac permease). Then three-dimensional models of the neurotransmitter transporters hDAT, hSERT and hNET were constructed based on the NhaA model and studies of ligand binding to mutated dopamine transporter (DAT) and serotonin transporter (SERT). The structural properties of these neurotransmitter transporter models have been examined, and their interactions with cocaine and S-citalopram have been investigated.
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Affiliation(s)
- Aina Westrheim Ravna
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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45
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Klingenberg M. Transport catalysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1229-36. [PMID: 16806051 DOI: 10.1016/j.bbabio.2006.04.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 04/06/2006] [Accepted: 04/07/2006] [Indexed: 11/24/2022]
Abstract
Carrier linked solute transport through biomembranes is analysed with the viewpoint of catalysis. Different from enzymes, in carriers the unchanged substrate induces optimum fit in the transition state. The enhanced intrinsic binding energy pays for the energy required of the global conformation changes, thus decreasing the activation energy barrier. This "induced transition fit" (ITF) explains several phenomena of carrier transport, e.g., high or low affinity substrate requirements for unidirectional versus exchange, external energy requirement for "low affinity" transport, the existence of side specific inhibitors to ground states of the carrier, the requirement of external energy in active transport to supplement catalytic energy in addition to generate electrochemical gradients.
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Affiliation(s)
- Martin Klingenberg
- Institute Physiological Chemistry, University of Munich, Schillerstr 44, 80336 München, Germany.
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46
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Mack M, Grill S. Riboflavin analogs and inhibitors of riboflavin biosynthesis. Appl Microbiol Biotechnol 2006; 71:265-75. [PMID: 16607521 DOI: 10.1007/s00253-006-0421-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/06/2006] [Accepted: 03/06/2006] [Indexed: 11/30/2022]
Abstract
Flavins are active components of many enzymes. In most cases, riboflavin (vitamin B(2)) as a coenzyme represents the catalytic part of the holoenzyme. Riboflavin is an amphiphatic molecule and allows a large variety of different interactions with the enzyme itself and also with the substrate. A great number of active riboflavin analogs can readily be synthesized by chemical methods and, thus, a large number of possible inhibitors for many different enzyme targets is conceivable. As mammalian and especially human biochemistry depends on flavins as well, the target of the inhibiting flavin analog has to be carefully selected to avoid unwanted effects. In addition to flavoproteins, enzymes, which are involved in the biosynthesis of flavins, are possible targets for anti-infectives. Only a few flavin analogs or inhibitors of flavin biosynthesis have been subjected to detailed studies to evaluate their biological activity. Nevertheless, flavin analogs certainly have the potential to serve as basic structures for the development of novel anti-infectives and it is possible that, in the future, the urgent need for new molecules to fight multiresistant microorganisms will be met.
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Affiliation(s)
- Matthias Mack
- Institute for Technical Microbiology, Mannheim University of Applied Sciences, Germany.
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47
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Mamaev DV, Aliverdieva DA, Bondarenko DI, Sholtz KF. Study of active site topography of rat liver mitochondrial dicarboxylate transporter using lipophilic substrate derivatives. BIOCHEMISTRY (MOSCOW) 2006; 71:800-9. [PMID: 16903835 DOI: 10.1134/s0006297906070133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Earlier it has been demonstrated that the active site (substrate-binding site + active site channel) of rat liver mitochondrial dicarboxylate transporter is characterized by rather complex topography. Probing the active site with 2-monoalkylmalonates revealed the existence of internal and external lipophilic areas separated by a polar region. A two substrate-binding site model of the transporter has been supposed. The correctness of this model has been evaluated by probing the active site with O-acyl-L-malates differing from 2-monoalkylmalonates by 0.23 nm longer distance from the anion groups to the aliphatic chain. Changes in the polar group of the probe did not prevent its binding and showed the same variable lipophilicity pattern for the transporter channel. Probing with alpha,omega-alkylene dimalonates did not reveal the second substrate-binding site at the active site. The substrate-binding site did not show any differences in affinity to O-acyl-derivatives of L-malate and D-malate, except L-malate binds more effectively than D-malate. This suggests involvement of the L-malate hydroxyl group in substrate binding and stereospecific behavior of the transporter substrate-binding site. A modified one substrate-binding site model of the dicarboxylate transporter is discussed.
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Affiliation(s)
- D V Mamaev
- Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071, Russia
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48
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Abstract
The era of molecular biology and cloning brought new knowledge about the structure and function of drug receptors, and demonstrated that the term 'receptor' must be distinguished from other molecular drug targets such as enzymes, transporters and ion channels. Analysis of the targets of all current therapeutic drugs has shown that more than 95% of these are proteins. The DNA sequencing of the entire human genome has led to identification of many previously unknown proteins that may represent potential drug targets. In order to understand fully the functional mechanisms of a protein, it is crucial to know its three-dimensional molecular structure. This may be determined experimentally by x-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy or electron microscopy, and computationally by structural bioinformatics and molecular modelling. The molecular targets of nearly all current psychotropic drugs are membrane proteins. These have proven extremely difficult to purify and crystallize due to their amphipathic surface, with a hydrophobic area in contact with membrane phospholipids and polar surface areas in contact with the aqueous phases on both sides of the membrane. We have used molecular modelling methods, based on crystal structures of related proteins, to model various neurotransmitter receptors and transporters. The receptor and transporter models have been used to study their structural properties, functional mechanisms and the molecular mechanisms of action of psychotropic drugs. Our results demonstrate the large structural flexibility of transporter and receptor proteins, with substantial movements and conformational changes taking place during substrate translocation in transporters, and by agonist induced receptor stimulation.
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Affiliation(s)
- Svein G Dahl
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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49
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Peer D, Margalit R. Fluoxetine and reversal of multidrug resistance. Cancer Lett 2006; 237:180-7. [PMID: 16014320 DOI: 10.1016/j.canlet.2005.06.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 06/07/2005] [Indexed: 01/16/2023]
Abstract
This review centers on recent findings with respect to modulating cancer multidrug resistance (MDR) with the well-known antidepressant fluoxetine (prozac). The MDR phenomena and mechanisms are discussed, including the roles of ABC transporters as MDR-pumps and the potential involvement of cancer stem cells. The three generations of MDR reversal agents (chemosensitizers) are reviewed, introducing the concept of single-pump and multi-pump agents. The current status of chemosensitization is summarized, pointing-out the need for additional agents and outlining experimental criteria for testing novel candidates. Major in vitro and in vivo findings are summarized showing that fluoxetine is a chemosensitizer of the multi-pump type, and proposing it be considered a fourth-generation chemosensitizer. In concluding, we contemplate future prospects of modulating MDR in the clinic.
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Affiliation(s)
- Dan Peer
- Department of Biochemistry, George S. Wise Life Science Faculty, Tel Aviv University, Tel Aviv 69978, Israel
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Allen DD, Geldenhuys WJ. Molecular modeling of blood–brain barrier nutrient transporters: In silico basis for evaluation of potential drug delivery to the central nervous system. Life Sci 2006; 78:1029-33. [PMID: 16126231 DOI: 10.1016/j.lfs.2005.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2005] [Accepted: 06/07/2005] [Indexed: 11/27/2022]
Abstract
For drugs that act in the brain, the blood-brain barrier (BBB) is a considerable physical barrier which influences the distribution of drugs to the brain. The BBB is essentially impermeable for hydrophilic and/or charged compounds. Nutrient membrane transporters have an important physiological role in the transport of essential substances across the BBB required for normal brain function. We and others have shown that these transporters may have utility as drug delivery vectors, thereby increasing brain distribution of these compounds via these systems. In this review, we evaluate molecular (in silico) models of BBB transport proteins. Few BBB membrane transporters have been crystallized, but their crystal structures have a possibility for use in homology modeling. Other techniques commonly used are 2D quantitative structure-activity relationships (QSAR), as well as 3D-QSAR techniques including comparative molecular field analysis (CoMFA) and comparative similarity index analysis (CoMSIA). Each of these models provides valuable information for ascertaining their potential basis for BBB transport and brain drug delivery.
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Affiliation(s)
- David D Allen
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Science Center, Amarillo, TX 79106, USA.
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