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Li Y, Mohanty S, Nilsson D, Hansson B, Mao K, Irbäck A. When a foreign gene meets its native counterpart: computational biophysics analysis of two PgiC loci in the grass Festuca ovina. Sci Rep 2020; 10:18752. [PMID: 33127989 PMCID: PMC7599235 DOI: 10.1038/s41598-020-75650-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/16/2020] [Indexed: 11/14/2022] Open
Abstract
Duplicative horizontal gene transfer may bring two previously separated homologous genes together, which may raise questions about the interplay between the gene products. One such gene pair is the “native” PgiC1 and “foreign” PgiC2 in the perennial grass Festuca ovina. Both PgiC1 and PgiC2 encode cytosolic phosphoglucose isomerase, a dimeric enzyme whose proper binding is functionally essential. Here, we use biophysical simulations to explore the inter-monomer binding of the two homodimers and the heterodimer that can be produced by PgiC1 and PgiC2 in F. ovina. Using simulated native-state ensembles, we examine the structural properties and binding tightness of the dimers. In addition, we investigate their ability to withstand dissociation when pulled by a force. Our results suggest that the inter-monomer binding is tighter in the PgiC2 than the PgiC1 homodimer, which could explain the more frequent occurrence of the foreign PgiC2 homodimer in dry habitats. We further find that the PgiC1 and PgiC2 monomers are compatible with heterodimer formation; the computed binding tightness is comparable to that of the PgiC1 homodimer. Enhanced homodimer stability and capability of heterodimer formation with PgiC1 are properties of PgiC2 that may contribute to the retaining of the otherwise redundant PgiC2 gene.
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Affiliation(s)
- Yuan Li
- Computational Biology and Biological Physics, Department of Astronomy and Theoretical Physics, Lund University, 223 62, Lund, Sweden
| | - Sandipan Mohanty
- Institute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Daniel Nilsson
- Computational Biology and Biological Physics, Department of Astronomy and Theoretical Physics, Lund University, 223 62, Lund, Sweden
| | - Bengt Hansson
- Department of Biology, Lund University, 223 62, Lund, Sweden
| | - Kangshan Mao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Anders Irbäck
- Computational Biology and Biological Physics, Department of Astronomy and Theoretical Physics, Lund University, 223 62, Lund, Sweden.
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Gulati K, Gangele K, Kumar D, Poluri KM. An inter-switch between hydrophobic and charged amino acids generated druggable small molecule binding pocket in chemokine paralog CXCL3. Arch Biochem Biophys 2018; 662:121-128. [PMID: 30528777 DOI: 10.1016/j.abb.2018.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/29/2018] [Accepted: 12/04/2018] [Indexed: 12/27/2022]
Abstract
Multigene families such as chemokines arose as a result of gene duplication events, followed by mutations and selection. GRO chemokines are three duplicated CXCL genes, comprising of CXCL1, CXCL2 and CXCL3 proteins. Comparative structural analysis of the two closely related paralog chemokines CXCL2 and CXCL3 in the current study indicated a variable electrostatic surface between them, and a specific hydrophobic pocket on the surface of CXCL3 that can bind naphthalene derivatives. Combined fluorescence and NMR analyses revealed that CXCL3 monomer can specifically bind to ANS (8-Anilinonaphthalene-1-sulfonic acid) with a stoichiometry of 1:1 by involving the residues belonging to the structural elements 310 helix and the α-helix. A close observation of the surfaces of these paralogs suggested that such a hydrophobic pocket is a resultant of inter-switch between a charged and a hydrophobic residue on the primary sequence of the two paralog proteins. Interestingly, the hydrophobic pocket is in the vicinity of GAG binding region of CXCL3, a molecular determinant in leukocyte trafficking. Such unique pockets/patches on specific chemokine surfaces can be exploited to design the naphthalene/small molecule based inhibitors against GAG binding to regulate their molecular interactions during the onset and progression of various types of cancers and inflammatory diseases.
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Affiliation(s)
- Khushboo Gulati
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Krishnakant Gangele
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Dinesh Kumar
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow, 226014, Uttar Pradesh, India
| | - Krishna Mohan Poluri
- Department of Biotechnology, 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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Gulati K, Jamsandekar M, Poluri KM. Mechanistic insights into molecular evolution of species-specific differential glycosaminoglycan binding surfaces in growth-related oncogene chemokines. ROYAL SOCIETY OPEN SCIENCE 2017; 4:171059. [PMID: 28989790 PMCID: PMC5627130 DOI: 10.1098/rsos.171059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 08/14/2017] [Indexed: 05/19/2023]
Abstract
Chemokines are chemotactic cytokines involved in leucocyte trafficking to infected tissue. Growth-related oncogene (GRO) chemokines namely CXCL1, CXCL2 and CXCL3 are neutrophil activating chemokines sharing a conserved three-dimensional structure, but encompassing functional diversity due to gene duplication and evolutionary events. However, the evolutionary mechanisms including selection pressures involved in diversification of GRO genes have not yet been characterized. Here, we performed comprehensive evolutionary analysis of GRO genes among different mammalian species. Phylogenetic analysis illustrated a species-specific evolution pattern. Selection analysis evidenced that these genes have undergone concerted evolution. Seventeen positively selected sites were obtained, although the majority of the protein is under purifying selection. Interestingly, these positively selected sites are more concentrated on the C-terminal/glycosaminoglycan (GAG) binding and dimerization segment compared to receptor binding domain. Substitution rate analysis confirmed the C-terminal domain of GRO genes as the highest substituted segment. Further, structural analysis established that the nucleotide alterations in the GAG binding domain are the source of surface charge modulation, thus generating the differential GAG binding surfaces and multiple binding sites as per evolutionary pressure, although the helical surface is primordial for GAG binding. Indeed, such variable electrostatic surfaces are crucial to regulate chemokine gradient formation during a host's defence against pathogens and also explain the significance of chemokine promiscuity.
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Affiliation(s)
- Khushboo Gulati
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Minal Jamsandekar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Krishna Mohan Poluri
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
- Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
- Author for correspondence: Krishna Mohan Poluri e-mail: ;
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4
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Tohyama S, Miyagawa S, Lange A, Ogino Y, Mizutani T, Ihara M, Tanaka H, Tatarazako N, Kobayashi T, Tyler CR, Iguchi T. Evolution of estrogen receptors in ray-finned fish and their comparative responses to estrogenic substances. J Steroid Biochem Mol Biol 2016; 158:189-197. [PMID: 26707410 DOI: 10.1016/j.jsbmb.2015.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 12/02/2015] [Accepted: 12/10/2015] [Indexed: 11/23/2022]
Abstract
In vertebrates, estrogens play fundamental roles in regulating reproductive activities through estrogen receptors (ESRs), and disruption of estrogen signaling is now of global concern for both wildlife and human health. To date, ESRs of only a limited number of species have been characterized. We investigated the functional diversity and molecular basis or ligand sensitivity of ESRs among ray-finned fish species (Actinopterygii), the most variable group within vertebrates. We cloned and characterized ESRs from several key species in the evolution of ray-finned fish including bichir (Polypteriformes, ESR1 and ESR2) at the basal lineage of ray-finned fish, and arowana (Osteoglossiformes, ESR1 and ESR2b) and eel (Anguilliformes, ESR1, ESR2a and ESR2b) both belonging to ancient early-branching lineages of teleosts, and suggest that ESR2a and ESR2b emerged through teleost-specific whole genome duplication, but an ESR1 paralogue has been lost in the early lineage of euteleost fish species. All cloned ESR isoforms showed similar responses to endogenous and synthetic steroidal estrogens, but they responded differently to non-steroidal estrogenic endocrine disrupting chemicals (EDCs) (e.g., ESR2a exhibits a weaker reporter activity compared with ESR2b). We show that variation in ligand sensitivity of ESRs can be attributed to phylogeny among species of different taxonomic groups in ray-finned fish. The molecular information provided contributes both to understanding of the comparative role of ESRs in the reproductive biology of fish and their comparative responses to EDCs.
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Affiliation(s)
- Saki Tohyama
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan; Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Shinichi Miyagawa
- Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan.
| | - Anke Lange
- University of Exeter, Biosciences, College of Life & Environmental Sciences, Exeter EX4 4QD, United Kingdom
| | - Yukiko Ogino
- Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Takeshi Mizutani
- Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Masaru Ihara
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga 520-0811, Japan
| | - Hiroaki Tanaka
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga 520-0811, Japan
| | - Norihisa Tatarazako
- Center for Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
| | - Tohru Kobayashi
- Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Charles R Tyler
- University of Exeter, Biosciences, College of Life & Environmental Sciences, Exeter EX4 4QD, United Kingdom
| | - Taisen Iguchi
- Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan.
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Vij S, Kuhl H, Kuznetsova IS, Komissarov A, Yurchenko AA, Van Heusden P, Singh S, Thevasagayam NM, Prakki SRS, Purushothaman K, Saju JM, Jiang J, Mbandi SK, Jonas M, Hin Yan Tong A, Mwangi S, Lau D, Ngoh SY, Liew WC, Shen X, Hon LS, Drake JP, Boitano M, Hall R, Chin CS, Lachumanan R, Korlach J, Trifonov V, Kabilov M, Tupikin A, Green D, Moxon S, Garvin T, Sedlazeck FJ, Vurture GW, Gopalapillai G, Kumar Katneni V, Noble TH, Scaria V, Sivasubbu S, Jerry DR, O'Brien SJ, Schatz MC, Dalmay T, Turner SW, Lok S, Christoffels A, Orbán L. Chromosomal-Level Assembly of the Asian Seabass Genome Using Long Sequence Reads and Multi-layered Scaffolding. PLoS Genet 2016; 12:e1005954. [PMID: 27082250 PMCID: PMC4833346 DOI: 10.1371/journal.pgen.1005954] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 03/03/2016] [Indexed: 11/18/2022] Open
Abstract
We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics.
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Affiliation(s)
- Shubha Vij
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Heiner Kuhl
- Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Inna S. Kuznetsova
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
- Laboratory of Chromosome Structure and Function, Department of Cytology and Histology, Biological Faculty, Saint Petersburg State University, St. Petersburg, Russia
| | - Aleksey Komissarov
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, St. Petersburg, Russia
| | - Andrey A. Yurchenko
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, St. Petersburg, Russia
| | - Peter Van Heusden
- South African MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Bellville, South Africa
| | - Siddharth Singh
- Pacific Biosciences, Menlo Park, California, United States of America
| | | | | | | | - Jolly M. Saju
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Junhui Jiang
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Stanley Kimbung Mbandi
- South African MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Bellville, South Africa
| | - Mario Jonas
- South African MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Bellville, South Africa
| | - Amy Hin Yan Tong
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Sarah Mwangi
- South African MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Bellville, South Africa
| | - Doreen Lau
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Si Yan Ngoh
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Woei Chang Liew
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Xueyan Shen
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
| | - Lawrence S. Hon
- Pacific Biosciences, Menlo Park, California, United States of America
| | - James P. Drake
- Pacific Biosciences, Menlo Park, California, United States of America
| | - Matthew Boitano
- Pacific Biosciences, Menlo Park, California, United States of America
| | - Richard Hall
- Pacific Biosciences, Menlo Park, California, United States of America
| | - Chen-Shan Chin
- Pacific Biosciences, Menlo Park, California, United States of America
| | | | - Jonas Korlach
- Pacific Biosciences, Menlo Park, California, United States of America
| | - Vladimir Trifonov
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | - Marsel Kabilov
- Genomics Core Facility, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Alexey Tupikin
- Genomics Core Facility, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Darrell Green
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Simon Moxon
- The Genome Analysis Centre, Norwich, United Kingdom
| | - Tyler Garvin
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, New York, United States of America
| | - Fritz J. Sedlazeck
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, New York, United States of America
- Department of Computer Science, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Gregory W. Vurture
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, New York, United States of America
| | - Gopikrishna Gopalapillai
- Nutrition, Genetics & Biotechnology Division, ICAR-Central Institute of Brackishwater Aquaculture, Tamil Nadu, India
| | - Vinaya Kumar Katneni
- Nutrition, Genetics & Biotechnology Division, ICAR-Central Institute of Brackishwater Aquaculture, Tamil Nadu, India
| | - Tansyn H. Noble
- College of Marine and Environmental Sciences and Center for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, Australia
| | - Vinod Scaria
- CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, India
| | - Sridhar Sivasubbu
- CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, India
| | - Dean R. Jerry
- College of Marine and Environmental Sciences and Center for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, Australia
| | - Stephen J. O'Brien
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, St. Petersburg, Russia
- Oceanographic Center, Nova Southeastern University Ft. Lauderdale, Ft. Lauderdale, Florida, United States of America
| | - Michael C. Schatz
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, New York, United States of America
- Department of Computer Science, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Tamás Dalmay
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Stephen W. Turner
- Pacific Biosciences, Menlo Park, California, United States of America
| | - Si Lok
- The Centre for Applied Genomics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Alan Christoffels
- South African MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of the Western Cape, Bellville, South Africa
| | - László Orbán
- Reproductive Genomics Group, Temasek Life Sciences Laboratory, Singapore
- Department of Animal Sciences and Animal Husbandry, Georgikon Faculty, University of Pannonia, Keszthely, Hungary
- Centre for Comparative Genomics, Murdoch University, Murdoch, Australia
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Tine M. Evolutionary significance and diversification of the phosphoglucose isomerase genes in vertebrates. BMC Res Notes 2015; 8:799. [PMID: 26682538 PMCID: PMC4684624 DOI: 10.1186/s13104-015-1683-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/09/2015] [Indexed: 01/20/2024] Open
Abstract
Background Phosphoglucose isomerase (PGI) genes are important multifunctional proteins whose evolution has, until now, not been well elucidated because of the limited number of completely sequenced genomes. Although the multifunctionality of this gene family has been considered as an original and innate characteristic, PGI genes may have acquired novel functions through changes in coding sequences and exon/intron structure, which are known to lead to functional divergence after gene duplication. A whole-genome comparative approach was used to estimate the rates of molecular evolution of this protein family. Results The results confirm the presence of two isoforms in teleost fishes and only one variant in all other vertebrates. Phylogenetic reconstructions grouped the PGI genes into five main groups: lungfishes/coelacanth/cartilaginous fishes, teleost fishes, amphibians, reptiles/birds and mammals, with the teleost group being subdivided into two subclades comprising PGI1 and PGI2. This PGI partitioning into groups is consistent with the synteny and molecular evolution results based on the estimation of the ratios of nonsynonymous to synonymous changes (Ka/Ks) and divergence rates between both PGI paralogs and orthologs. Teleost PGI2 shares more similarity with the variant found in all other vertebrates, suggesting that it has less evolved than PGI1 relative to the PGI of common vertebrate ancestor. Conclusions The diversification of PGI genes into PGI1 and PGI2 is consistent with a teleost-specific duplication before the radiation of this lineage, and after its split from the other infraclasses of ray-finned fishes. The low average Ka/Ks ratios within teleost and mammalian lineages suggest that both PGI1 and PGI2 are functionally constrained by purifying selection and may, therefore, have the same functions. By contrast, the high average Ka/Ks ratios and divergence rates within reptiles and birds indicate that PGI may be involved in different functions. The synteny analyses show that the genomic region harbouring PGI genes has independently undergone genomic rearrangements in mammals versus the reptile/bird lineage in particular, which may have contributed to the actual functional diversification of this gene family. Electronic supplementary material The online version of this article (doi:10.1186/s13104-015-1683-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mbaye Tine
- Molecular Zoology Laboratory, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa. .,Genome Centre Cologne at MPI for Plant Breeding Research, 22 Carl-von-Linné-Weg 10, 50829, Cologne, Germany.
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The circadian clock of teleost fish: a comparative analysis reveals distinct fates for duplicated genes. J Mol Evol 2014; 80:57-64. [PMID: 25487517 DOI: 10.1007/s00239-014-9660-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 11/26/2014] [Indexed: 10/24/2022]
Abstract
The circadian clock is a central oscillator that coordinates endogenous rhythms. Members of six gene families underlie the metabolic machinery of this system. Although this machinery appears to correspond to a highly conserved genetic system in metazoans, it has been recognized that vertebrates possess a more diverse gene inventory than that of non-vertebrates. This difference could have originated in the two successive rounds of whole-genome duplications that took place in the common ancestor of the group. Teleost fish underwent an extra event of whole-genome duplication, which is thought to have provided an abundance of raw genetic material for the biological innovations that facilitated the radiation of the group. In this study, we assessed the relative contributions of whole-genome duplication and small-scale gene duplication to generate the repertoire of genes associated with the circadian clock of teleost fish. To achieve this goal, we annotated genes from six gene families associated with the circadian clock in eight teleost fish species, and we reconstructed their evolutionary history by inferring phylogenetic relationships. Our comparative analysis indicated that teleost species possess a variable repertoire of genes related to the circadian clock gene families and that the actual diversity of these genes has been shaped by a variety of phenomena, such as the complete deletion of ohnologs, the differential retention of genes, and lineage-specific gene duplications. From a functional perspective, the subfunctionalization of two ohnolog genes (PER1a and PER1b) in zebrafish highlights the power of whole-genome duplications to generate biological diversity.
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Kaiya H, Konno N, Kangawa K, Uchiyama M, Miyazato M. Identification, tissue distribution and functional characterization of the ghrelin receptor in West African lungfish, Protopterus annectens. Gen Comp Endocrinol 2014; 209:106-17. [PMID: 25093625 DOI: 10.1016/j.ygcen.2014.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 07/16/2014] [Accepted: 07/26/2014] [Indexed: 12/29/2022]
Abstract
We identified two ghrelin receptor isoforms, the ghrelin receptor type-1a (GHS-R1a) and its alternative splice form (GHS-R1b) for West African lungfish, Protopterus annectens. Lungfish GHS-R1a and 1b comprised 361 and 281 amino acids, respectively. Lungfish GHS-R1a showed the highest identity to coelacanth GHS-R1a (80.4%). The highest expression of GHS-R1a mRNAs was seen in the brain, liver, ovary, heart, intestine, and gills. GHS-R1b mRNAs were also detected in the same tissues with GHS-R1a, but their expression level was 1/20 that of GHS-R1a. In human embryonic kidney 293 cells transiently expressing lungfish GHS-R1a, rat and bullfrog ghrelin, and two GHS-R1a agonists, GHRP-6 and hexarelin, increased intracellular Ca(2+) concentrations. The intensity of the Ca(2+) increases induced by GHS-R1a agonists was twice when compared to that induced by ghrelin, although the median effective doses (ED50) were similar, suggesting a long-lasting effect of GHS-R1a agonists with similar affinity. We also examined changes in the GHS-R gene expression during an eight-week estivation. Body weight was slightly lowered, but plasma sodium and glucose concentrations decreased; plasma urea concentration increased significantly 4weeks after the start of estivation. Overall, expression of GHS-R1a mRNA decreased, but changes in GHS-R1b mRNA expression were inconsistent with those of GHS-R1a during estivation, suggesting an involvement of GHS-R in energy homeostasis, as seen in mammals. Our results suggest that the ghrelin-GHS-R1a system is present in this lungfish although ghrelin has not yet been found. The structure of GHS-R1a is closer to that of tetrapods than Actinopterygian fish, indicating a process of evolution that follows the Crossopterygii such as coelacanth.
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Affiliation(s)
- Hiroyuki Kaiya
- Department of Biochemistry, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.
| | - Norifumi Konno
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Kenji Kangawa
- Department of Biochemistry, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| | - Minoru Uchiyama
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Mikiya Miyazato
- Department of Biochemistry, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
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9
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Dunning LT, Dennis AB, Thomson G, Sinclair BJ, Newcomb RD, Buckley TR. Positive selection in glycolysis among Australasian stick insects. BMC Evol Biol 2013; 13:215. [PMID: 24079656 PMCID: PMC3850572 DOI: 10.1186/1471-2148-13-215] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 09/23/2013] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND The glycolytic pathway is central to cellular energy production. Selection on individual enzymes within glycolysis, particularly phosphoglucose isomerase (Pgi), has been associated with metabolic performance in numerous organisms. Nonetheless, how whole energy-producing pathways evolve to allow organisms to thrive in different environments and adopt new lifestyles remains little explored. The Lanceocercata radiation of Australasian stick insects includes transitions from tropical to temperate climates, lowland to alpine habitats, and winged to wingless forms. This permits a broad investigation to determine which steps within glycolysis and what sites within enzymes are the targets of positive selection. To address these questions we obtained transcript sequences from seven core glycolysis enzymes, including two Pgi paralogues, from 29 Lanceocercata species. RESULTS Using maximum likelihood methods a signature of positive selection was inferred in two core glycolysis enzymes. Pgi and Glyceraldehyde 3-phosphate dehydrogenase (Gaphd) genes both encode enzymes linking glycolysis to the pentose phosphate pathway. Positive selection among Pgi paralogues and orthologues predominately targets amino acids with residues exposed to the protein's surface, where changes in physical properties may alter enzyme performance. CONCLUSION Our results suggest that, for Lancerocercata stick insects, adaptation to new stressful lifestyles requires a balance between maintaining cellular energy production, efficiently exploiting different energy storage pools and compensating for stress-induced oxidative damage.
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Affiliation(s)
- Luke T Dunning
- Landcare Research, Private Bag 92170, Auckland, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, Auckland, New Zealand
- Imperial College London, Silwood Park Campus, Buckhurst Road, SL5 7PY, Ascot, Berks, UK
| | - Alice B Dennis
- Landcare Research, Private Bag 92170, Auckland, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, Auckland, New Zealand
| | - Geoffrey Thomson
- Landcare Research, Private Bag 92170, Auckland, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Brent J Sinclair
- Department of Biology, The University of Western Ontario, London, ON, Canada N6G 1L3
| | - Richard D Newcomb
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, Auckland, New Zealand
- The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Thomas R Buckley
- Landcare Research, Private Bag 92170, Auckland, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, Auckland, New Zealand
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10
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Kulmuni J, Havukainen H. Insights into the evolution of the CSP gene family through the integration of evolutionary analysis and comparative protein modeling. PLoS One 2013; 8:e63688. [PMID: 23723994 PMCID: PMC3665776 DOI: 10.1371/journal.pone.0063688] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/05/2013] [Indexed: 01/10/2023] Open
Abstract
Insect chemical communication and chemosensory systems rely on proteins coded by several gene families. Here, we have combined protein modeling with evolutionary analysis in order to study the evolution and structure of chemosensory proteins (CSPs) within arthropods and, more specifically, in ants by using the data available from sequenced genomes. Ants and other social insects are especially interesting model systems for the study of chemosensation, as they communicate in a highly complex social context and much of their communication relies on chemicals. Our ant protein models show how this complexity has shaped CSP evolution; the proteins are highly modifiable by their size, surface charge and binding pocket. Based on these findings, we divide ant CSPs into three groups: typical insect CSPs, an ancient 5-helical CSP and hymenopteran CSPs with a small binding pocket, and suggest that these groups likely serve different functions. The hymenopteran CSPs have duplicated repeatedly in individual ant lineages. In these CSPs, positive selection has driven surface charge changes, an observation which has possible implications for the interaction between CSPs and ligands or odorant receptors. Our phylogenetic analysis shows that within the Arthropoda the only highly conserved gene is the ancient 5-helical CSP, which is likely involved in an essential ubiquitous function rather than chemosensation. During insect evolution, the 6-helical CSPs have diverged and perform chemosensory functions among others. Our results contribute to the general knowledge of the structural differences between proteins underlying chemosensation and highlight those protein properties which have been affected by adaptive evolution.
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Affiliation(s)
- Jonna Kulmuni
- Department of Biology and Biocenter Oulu, University of Oulu, Oulu, Finland.
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12
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Opazo JC, Butts GT, Nery MF, Storz JF, Hoffmann FG. Whole-genome duplication and the functional diversification of teleost fish hemoglobins. Mol Biol Evol 2012; 30:140-53. [PMID: 22949522 PMCID: PMC3525417 DOI: 10.1093/molbev/mss212] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Subsequent to the two rounds of whole-genome duplication that occurred in the common
ancestor of vertebrates, a third genome duplication occurred in the stem lineage of
teleost fishes. This teleost-specific genome duplication (TGD) is thought to have provided
genetic raw materials for the physiological, morphological, and behavioral diversification
of this highly speciose group. The extreme physiological versatility of teleost fish is
manifest in their diversity of blood–gas transport traits, which reflects the myriad
solutions that have evolved to maintain tissue O2 delivery in the face of
changing metabolic demands and environmental O2 availability during different
ontogenetic stages. During the course of development, regulatory changes in
blood–O2 transport are mediated by the expression of multiple,
functionally distinct hemoglobin (Hb) isoforms that meet the particular
O2-transport challenges encountered by the developing embryo or fetus (in
viviparous or oviparous species) and in free-swimming larvae and adults. The main
objective of the present study was to assess the relative contributions of whole-genome
duplication, large-scale segmental duplication, and small-scale gene duplication in
producing the extraordinary functional diversity of teleost Hbs. To accomplish this, we
integrated phylogenetic reconstructions with analyses of conserved synteny to characterize
the genomic organization and evolutionary history of the globin gene clusters of teleosts.
These results were then integrated with available experimental data on functional
properties and developmental patterns of stage-specific gene expression. Our results
indicate that multiple α- and β-globin genes
were present in the common ancestor of gars (order Lepisoteiformes) and teleosts. The
comparative genomic analysis revealed that teleosts possess a dual set of TGD-derived
globin gene clusters, each of which has undergone lineage-specific changes in gene content
via repeated duplication and deletion events. Phylogenetic reconstructions revealed that
paralogous genes convergently evolved similar functional properties in different teleost
lineages. Consistent with other recent studies of globin gene family evolution in
vertebrates, our results revealed evidence for repeated evolutionary transitions in the
developmental regulation of Hb synthesis.
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Affiliation(s)
- Juan C Opazo
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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Kuravsky ML, Aleshin VV, Frishman D, Muronetz VI. Testis-specific glyceraldehyde-3-phosphate dehydrogenase: origin and evolution. BMC Evol Biol 2011; 11:160. [PMID: 21663662 PMCID: PMC3224139 DOI: 10.1186/1471-2148-11-160] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 06/10/2011] [Indexed: 11/25/2022] Open
Abstract
Background Glyceraldehyde-3-phosphate dehydrogenase (GAPD) catalyses one of the glycolytic reactions and is also involved in a number of non-glycolytic processes, such as endocytosis, DNA excision repair, and induction of apoptosis. Mammals are known to possess two homologous GAPD isoenzymes: GAPD-1, a well-studied protein found in all somatic cells, and GAPD-2, which is expressed solely in testis. GAPD-2 supplies energy required for the movement of spermatozoa and is tightly bound to the sperm tail cytoskeleton by the additional N-terminal proline-rich domain absent in GAPD-1. In this study we investigate the evolutionary history of GAPD and gain some insights into specialization of GAPD-2 as a testis-specific protein. Results A dataset of GAPD sequences was assembled from public databases and used for phylogeny reconstruction by means of the Bayesian method. Since resolution in some clades of the obtained tree was too low, syntenic analysis was carried out to define the evolutionary history of GAPD more precisely. The performed selection tests showed that selective pressure varies across lineages and isoenzymes, as well as across different regions of the same sequences. Conclusions The obtained results suggest that GAPD-1 and GAPD-2 emerged after duplication during the early evolution of chordates. GAPD-2 was subsequently lost by most lineages except lizards, mammals, as well as cartilaginous and bony fishes. In reptilians and mammals, GAPD-2 specialized to a testis-specific protein and acquired the novel N-terminal proline-rich domain anchoring the protein in the sperm tail cytoskeleton. This domain is likely to have originated by exonization of a microsatellite genomic region. Recognition of the proline-rich domain by cytoskeletal proteins seems to be unspecific. Besides testis, GAPD-2 of lizards was also found in some regenerating tissues, but it lacks the proline-rich domain due to tissue-specific alternative splicing.
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Affiliation(s)
- Mikhail L Kuravsky
- Faculty of Bioengineering and Bioinformatics, MV Lomonosov Moscow State University, Moscow, Russian Federation
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Doumen C. cDNA identification, comparison and phylogenetic aspects of lombricine kinase from two oligochaete species. Comp Biochem Physiol B Biochem Mol Biol 2010; 156:137-43. [PMID: 20230902 DOI: 10.1016/j.cbpb.2010.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 03/08/2010] [Accepted: 03/09/2010] [Indexed: 11/18/2022]
Abstract
Creatine kinase and arginine kinase are the typical representatives of an eight-member phosphagen kinase family, which play important roles in the cellular energy metabolism of animals. The phylum Annelida underwent a series of evolutionary processes that resulted in rapid divergence and radiation of these enzymes, producing the greatest diversity of the phosphagen kinases within this phylum. Lombricine kinase (EC 2.7.3.5) is one of such enzymes and sequence information is rather limited compared to other phosphagen kinases. This study presents data on the cDNA sequences of lombricine kinase from two oligochaete species, the California blackworm (Lumbriculus variegatus) and the sludge worm (Tubifex tubifex). The deduced amino acid sequences are analyzed and compared with other selected phosphagen kinases, including two additional lombricine kinase sequences extracted from DNA databases and provide further insights in the evolution and position of these enzymes within the phosphagen kinase family. The data confirms the presence of a deleted region within the flexible loop (the GS region) of all six examined lombricine kinases. A phylogenetic analysis of these six lombricine kinases clearly positions the enzymes together in a small subcluster within the larger creatine kinase (EC 2.7.3.2) clade.
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Affiliation(s)
- Chris Doumen
- Collin College, Department of Mathematics and Natural Sciences, Plano, TX 75074, USA.
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Phosphoglucose isomerase (Pgi) performance and fitness effects among Arthropods and its potential role as an adaptive marker in conservation genetics. CONSERV GENET 2010. [DOI: 10.1007/s10592-009-0042-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Sato Y, Hashiguchi Y, Nishida M. Temporal pattern of loss/persistence of duplicate genes involved in signal transduction and metabolic pathways after teleost-specific genome duplication. BMC Evol Biol 2009; 9:127. [PMID: 19500364 PMCID: PMC2702319 DOI: 10.1186/1471-2148-9-127] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Accepted: 06/05/2009] [Indexed: 11/10/2022] Open
Abstract
Background Recent genomic studies have revealed a teleost-specific third-round whole genome duplication (3R-WGD) event occurred in a common ancestor of teleost fishes. However, it is unclear how the genes duplicated in this event were lost or persisted during the diversification of teleosts, and therefore, how many of the duplicated genes contribute to the genetic differences among teleosts. This subject is also important for understanding the process of vertebrate evolution through WGD events. We applied a comparative evolutionary approach to this question by focusing on the genes involved in long-term potentiation, taste and olfactory transduction, and the tricarboxylic acid cycle, based on the whole genome sequences of four teleosts; zebrafish, medaka, stickleback, and green spotted puffer fish. Results We applied a state-of-the-art method of maximum-likelihood phylogenetic inference and conserved synteny analyses to each of 130 genes involved in the above biological systems of human. These analyses identified 116 orthologous gene groups between teleosts and tetrapods, and 45 pairs of 3R-WGD-derived duplicate genes among them. This suggests that more than half [(45×2)/(116+45)] = 56.5%) of the loci, probably more than ten thousand genes, present in a common ancestor of the four teleosts were still duplicated after the 3R-WGD. The estimated temporal pattern of gene loss suggested that, after the 3R-WGD, many (71/116) of the duplicated genes were rapidly lost during the initial 75 million years (MY), whereas on average more than half (27.3/45) of the duplicated genes remaining in the ancestor of the four teleosts (45/116) have persisted for about 275 MY. The 3R-WGD-derived duplicates that have persisted for a long evolutionary periods of time had significantly larger number of interacting partners and longer length of protein coding sequence, implying that they tend to be more multifunctional than the singletons after the 3R-WGD. Conclusion We have shown firstly the temporal pattern of gene loss process after 3R-WGD on the basis of teleost phylogeny and divergence time frameworks. The 3R-WGD-derived duplicates have not undergone constant exponential decay, suggesting that selection favoured the long-term persistence of a subset of duplicates that tend to be multi-functional. On the basis of these results obtained from the analysis of 116 orthologous gene groups, we propose that more than ten thousand of 3R-WGD-derived duplicates have experienced lineage-specific evolution, that is, the differential sub-/neo-functionalization or secondary loss between lineages, and contributed to teleost diversity.
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Affiliation(s)
- Yukuto Sato
- Division of Molecular Marine Biology, Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan.
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Lin WW, Chen LH, Chen MC, Kao HW. Differential expression of zebrafish gpia and gpib during development. Gene Expr Patterns 2009; 9:238-45. [DOI: 10.1016/j.gep.2008.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2008] [Revised: 12/20/2008] [Accepted: 12/22/2008] [Indexed: 10/21/2022]
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Sato Y, Hashiguchi Y, Nishida M. Evolution of multiple phosphodiesterase isoforms in stickleback involved in cAMP signal transduction pathway. BMC SYSTEMS BIOLOGY 2009; 3:23. [PMID: 19232106 PMCID: PMC2653465 DOI: 10.1186/1752-0509-3-23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 02/20/2009] [Indexed: 11/10/2022]
Abstract
Background Duplicate genes are considered to have evolved through the partitioning of ancestral functions among duplicates (subfunctionalization) and/or the acquisition of novel functions from a beneficial mutation (neofunctionalization). Additionally, an increase in gene dosage resulting from duplication may also confer an advantageous effect, as has been suggested for histone, tRNA, and rRNA genes. Currently, there is little understanding of the effect of increased gene dosage on subcellular networks like signal transduction pathways. Addressing this issue may provide further insights into the evolution by gene duplication. Results We analyzed the evolution of multiple stickleback phosphodiesterase (PDE, EC: 3.1.4.17) 1C genes involved in the cyclic nucleotide signaling pathway. Stickleback has 8–9 copies of this gene, whereas only one or two loci exist in other model vertebrates. Our phylogenetic and synteny analyses suggested that the multiple PDE1C genes in stickleback were generated by repeated duplications of >100-kbp chromosome segments. Sequence evolution analysis did not provide strong evidence for neofunctionalization in the coding sequences of stickleback PDE1C isoforms. On the other hand, gene expression analysis suggested that the derived isoforms acquired expression in new organs, implying their neofunctionalization in terms of expression patterns. In addition, at least seven isoforms of the stickleback PDE1C were co-expressed with olfactory-type G-proteins in the nose, suggesting that PDE1C dosage is increased in the stickleback olfactory transduction (OT) pathway. In silico simulations of OT implied that the increased PDE1C dosage extends the longevity of the depolarization signals of the olfactory receptor neuron. Conclusion The predicted effect of the increase in PDE1C products on the OT pathway may play an important role in stickleback behavior and ecology. However, this possibility should be empirically examined. Our analyses imply that an increase in gene product sometimes has a significant, yet unexpected, effect on the functions of subcellular networks.
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Affiliation(s)
- Yukuto Sato
- Division of Molecular Marine Biology, Ocean Research Institute, The University of Tokyo, Tokyo, Japan.
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Sato Y, Nishida M. Electric charge divergence in proteins: insights into the evolution of their three-dimensional properties. Gene 2008; 441:3-11. [PMID: 18652881 DOI: 10.1016/j.gene.2008.06.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 06/13/2008] [Accepted: 06/17/2008] [Indexed: 11/28/2022]
Abstract
Previous studies of protein evolution have identified important mutations in various proteins that affect a small number of residues, but dramatically alter protein function. However, the evolutionary process underlying the three-dimensional protein properties, which are determined by a much larger number of residues, remains unclear. Based on a comparative evolutionary analysis of teleost phosphoglucose isomerases (PGIs; EC 5.3.1.9), we previously demonstrated that the relatively weak selection on many amino acid sites has played an important role in the evolution of protein electric charge as a model of three-dimensional protein properties. To ascertain the generality of this finding, we sought further evidence of this type of protein evolution. For this purpose, we analyzed the vertebrate isoforms of fructose-1,6-bisphosphate aldolase (ALD; EC 4.1.2.13), for which electric charges are known to have diverged after gene duplication. The results showed that the divergence in electric charge between the ALD isoforms was also driven by weak selection on many amino acid sites, as in PGI, confirming the generality of earlier findings. To obtain further insights, ALD and PGI were compared to the proteins pancreatic ribonuclease (EC 3.1.27.5) and triose-phosphate isomerase (EC 5.3.1.1), for which electric charges likely evolved through a well-defined mode of molecular evolution; namely, strong selection on specific amino acid sites. Comparison of the number and composition of amino acids on the protein surface suggested that the absolute number of evolutionarily changeable amino acids in a protein affects the strength of selection pressure acting on individual amino acid sites.
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Affiliation(s)
- Yukuto Sato
- Division of Molecular Marine Biology, Ocean Research Institute, University of Tokyo, Minamidai 1-15-1, Nakano-ku, Tokyo 164-8639, Japan.
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