1
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Bryłka K, Pinseel E, Roberts WR, Ruck EC, Conley DJ, Alverson AJ. Gene Duplication, Shifting Selection, and Dosage Balance of Silicon Transporter Proteins in Marine and Freshwater Diatoms. Genome Biol Evol 2023; 15:evad212. [PMID: 37996067 PMCID: PMC10700740 DOI: 10.1093/gbe/evad212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/15/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023] Open
Abstract
Numerous factors shape the evolution of protein-coding genes, including shifts in the strength or type of selection following gene duplications or changes in the environment. Diatoms and other silicifying organisms use a family of silicon transporters (SITs) to import dissolved silicon from the environment. Freshwaters contain higher silicon levels than oceans, and marine diatoms have more efficient uptake kinetics and less silicon in their cell walls, making them better competitors for a scarce resource. We compiled SITs from 37 diatom genomes to characterize shifts in selection following gene duplications and marine-freshwater transitions. A deep gene duplication, which coincided with a whole-genome duplication, gave rise to two gene lineages. One of them (SIT1-2) is present in multiple copies in most species and is known to actively import silicon. These SITs have evolved under strong purifying selection that was relaxed in freshwater taxa. Episodic diversifying selection was detected but not associated with gene duplications or habitat shifts. In contrast, genes in the second SIT lineage (SIT3) were present in just half the species, the result of multiple losses. Despite conservation of SIT3 in some lineages for the past 90-100 million years, repeated losses, relaxed selection, and low expression highlighted the dispensability of SIT3, consistent with a model of deterioration and eventual loss due to relaxed selection on SIT3 expression. The extensive but relatively balanced history of duplications and losses, together with paralog-specific expression patterns, suggest diatoms continuously balance gene dosage and expression dynamics to optimize silicon transport across major environmental gradients.
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Affiliation(s)
| | - Eveline Pinseel
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Wade R Roberts
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Elizabeth C Ruck
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | | | - Andrew J Alverson
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
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2
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Ratcliffe S, Meyer EM, Walker CE, Knight M, McNair HM, Matson PG, Iglesias-Rodriguez D, Brzezinski M, Langer G, Sadekov A, Greaves M, Brownlee C, Curnow P, Taylor AR, Wheeler GL. Characterization of the molecular mechanisms of silicon uptake in coccolithophores. Environ Microbiol 2023; 25:315-330. [PMID: 36397254 PMCID: PMC10098502 DOI: 10.1111/1462-2920.16280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 11/05/2022] [Indexed: 11/19/2022]
Abstract
Coccolithophores are an important group of calcifying marine phytoplankton. Although coccolithophores are not silicified, some species exhibit a requirement for Si in the calcification process. These species also possess a novel protein (SITL) that resembles the SIT family of Si transporters found in diatoms. However, the nature of Si transport in coccolithophores is not yet known, making it difficult to determine the wider role of Si in coccolithophore biology. Here, we show that coccolithophore SITLs act as Na+ -coupled Si transporters when expressed in heterologous systems and exhibit similar characteristics to diatom SITs. We find that CbSITL from Coccolithus braarudii is transcriptionally regulated by Si availability and is expressed in environmental coccolithophore populations. However, the Si requirement of C. braarudii and other coccolithophores is very low, with transport rates of exogenous Si below the level of detection in sensitive assays of Si transport. As coccoliths contain only low levels of Si, we propose that Si acts to support the calcification process, rather than forming a structural component of the coccolith itself. Si is therefore acting as a micronutrient in coccolithophores and natural populations are only likely to experience Si limitation in circumstances where dissolved silicon (DSi) is depleted to extreme levels.
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Affiliation(s)
| | - Erin M Meyer
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Charlotte E Walker
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, UK
| | - Michael Knight
- School of Ocean and Earth Science, University of Southampton, Southampton, UK
| | - Heather M McNair
- Department of Ecology Evolution and Marine Biology and the Marine Science Institute, University of California, Santa Barbara, California, USA
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Paul G Matson
- Department of Ecology Evolution and Marine Biology and the Marine Science Institute, University of California, Santa Barbara, California, USA
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Debora Iglesias-Rodriguez
- Department of Ecology Evolution and Marine Biology and the Marine Science Institute, University of California, Santa Barbara, California, USA
| | - Mark Brzezinski
- Department of Ecology Evolution and Marine Biology and the Marine Science Institute, University of California, Santa Barbara, California, USA
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Gerald Langer
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, UK
| | - Aleksey Sadekov
- ARC Centre of Excellence for Coral Reef Studies, Ocean Graduate School, University of Western Australia, Crawley, Western Australia, Australia
| | - Mervyn Greaves
- The Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Colin Brownlee
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, UK
| | - Paul Curnow
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Alison R Taylor
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Glen L Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, UK
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3
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Knight MJ, Hardy BJ, Wheeler GL, Curnow P. Computational modelling of diatom silicic acid transporters predicts a conserved fold with implications for their function and evolution. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184056. [PMID: 36191629 DOI: 10.1016/j.bbamem.2022.184056] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 11/27/2022]
Abstract
Diatoms are an important group of algae that can produce intricate silicified cell walls (frustules). The complex process of silicification involves a set of enigmatic integral membrane proteins that are thought to actively transport the soluble precursor of biosilica, dissolved silicic acid. Full-length silicic acid transporters are found widely across the diatoms while homologous shorter proteins have now been identified in a range of other organisms. It has been suggested that modern silicic acid transporters arose from the union of such partial sequences. Here, we present a computational study of the silicic acid transporters and related transporter-like sequences to help understand the structure, function and evolution of this class of membrane protein. The AlphaFold software predicts that all of the protein sequences studied here share a common fold in the membrane domain which is entirely different from the predicted folds of non-homologous silicic acid transporters from plants. Substrate docking reveals how conserved polar residues could interact with silicic acid at a central solvent-accessible binding site, consistent with an alternating access mechanism of transport. The structural conservation between these proteins supports a model where modern silicon transporters evolved from smaller ancestral proteins by gene fusion.
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Affiliation(s)
| | | | | | - Paul Curnow
- School of Biochemistry, University of Bristol, UK.
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4
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Lekklar C, Chadchawan S, Boon-Long P, Pfeiffer W, Chaidee A. Salt stress in rice: multivariate analysis separates four components of beneficial silicon action. PROTOPLASMA 2019; 256:331-347. [PMID: 30097762 DOI: 10.1007/s00709-018-1293-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
How many subcellular targets of the beneficial silicon effect do exist in salt-stressed rice? Here, we investigate the effects of silicon on the different components of salt stress, i.e., osmotic stress, sodium, and chloride toxicity. These components are separated by multivariate analysis of 18 variables measured in rice seedlings (Oryza sativa L.). Multivariate analysis can dissect vectors and extract targets as principal components, given the regressions between all variables are known. Consequently, the exploration of 153 correlations and 306 regression models between all variables is essential, and regression parameters for variables of shoot (silicon, sodium, chloride, carotenoids, chlorophylls a and b, and relative growth rate) and variables of shoot and root (hydrogen peroxide, ascorbate peroxidase (APX), catalase (CAT), fresh weight, dry weight, root-to-shoot ratio) are determined. The regression models [log (y) = y0 + a × log (x)] are confirmed by variance analysis of global goodness of fits (p < 0.0001). Thereby, logarithmic transformation yields linearization for multivariate analysis by Pearson's correlation. Four principal components are extracted: two targets of osmotic stress, one target of sodium toxicity, and one target of chloride toxicity. Thereby, silicon improves salt tolerance by increasing APX and CAT activities and decreasing hydrogen peroxide, salt ion accumulation, photosynthetic pigment losses, and growth inhibition. Salt stress increases silicon uptake pointing to a physiological regulation of plant salt stress in the presence of silicon. This mechanism and its four components are promising targets for further agricultural application.
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Affiliation(s)
- Chakkree Lekklar
- Center of Excellence in Environment and Plant Physiology, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Supachitra Chadchawan
- Center of Excellence in Environment and Plant Physiology, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Preeda Boon-Long
- Center of Excellence in Environment and Plant Physiology, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Wolfgang Pfeiffer
- Fachbereich Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Salzburg, 5020, Salzburg, Austria
| | - Anchalee Chaidee
- Center of Excellence in Environment and Plant Physiology, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
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5
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Saidel WM, Saglam N, Salas‐de la Cruz D, Saunders R, Shain DH. Elaborate ultrastructure of the
Hirudo
(Annelida: Hirudinae) cocoon surface. J Morphol 2017; 279:545-553. [DOI: 10.1002/jmor.20787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/20/2017] [Accepted: 11/23/2017] [Indexed: 11/11/2022]
Affiliation(s)
- William M. Saidel
- Department of BiologyRutgers The State University of New Jersey, 315 Penn StreetCamden New Jersey08102
| | - Naim Saglam
- Department of Aquaculture and Fish Diseases, Fisheries FacultyFirat UniversityElazig23119 Turkey
| | - David Salas‐de la Cruz
- Department of ChemistryRutgers, The State University of New Jersey, 315 Penn StreetCamden New Jersey08102
| | - Ralph Saunders
- Department of BiologyRutgers The State University of New Jersey, 315 Penn StreetCamden New Jersey08102
| | - Daniel H. Shain
- Department of BiologyRutgers The State University of New Jersey, 315 Penn StreetCamden New Jersey08102
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6
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Mishra M, Arukha AP, Bashir T, Yadav D, Prasad GBKS. All New Faces of Diatoms: Potential Source of Nanomaterials and Beyond. Front Microbiol 2017; 8:1239. [PMID: 28725218 PMCID: PMC5496942 DOI: 10.3389/fmicb.2017.01239] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/19/2017] [Indexed: 02/02/2023] Open
Abstract
Nature's silicon marvel, the diatoms have lately astounded the scientific community with its intricate designs and lasting durability. Diatoms are a major group of phytoplanktons involved in the biogeochemical cycling of silica and are virtually inherent in every environment ranging from water to ice to soil. The usage of diatoms has proved prudently cost effective and its handling neither requires costly materials nor sophisticated instruments. Diatoms can easily be acquired from the environment, their culture requires ambient condition and does not involve any costly media or expensive instruments, besides, they can be transported in small quantities and proliferated to a desirable confluence from that scratch, thus are excellent cost effective industrial raw material. Naturally occurring diatom frustules are a source of nanomaterials. Their silica bio-shells have raised curiosity among nanotechnologists who hope that diatoms will facilitate tailoring minuscule structures which are beyond the capabilities of material scientists. Additionally, there is a colossal diversity in the dimensions of diatoms as the frustule shape differs from species to species; this provides a scope for the choice of a particular species of diatom to be tailored to an exacting requisite, thus paving the way to create desired three dimensional nanocomposites. The present article explores the use of diatoms in various arenas of science, may it be in nanotechnology, biotechnology, environmental science, biophysics or biochemistry and summarizes facets of diatom biology under one umbrella. Special emphasis has been given to biosilicification, biomineralization and use of diatoms as nanomaterials', drug delivery vehicles, optical and immune-biosensors, filters, immunodiagnostics, aquaculture feeds, lab-on-a-chip, metabolites, and biofuels.
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Affiliation(s)
| | - Ananta P. Arukha
- Department of Infectious Diseases and Pathology, University of Florida, GainesvilleFL, United States
| | - Tufail Bashir
- School of Biotechnology, Yeungnam UniversityGyeongsan, South Korea
| | - Dhananjay Yadav
- Department of Medical Biotechnology, Yeungnam UniversityGyeongsan, South Korea
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7
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Grachev MA, Bedoshvili YD, Gerasimov EY, Zaikovskii VI, Gneusheva KV, Likhoshway YV. Silica-containing inclusions in the cytoplasm of diatom Synedra acus. DOKL BIOCHEM BIOPHYS 2017; 472:44-48. [DOI: 10.1134/s1607672917010124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Indexed: 11/23/2022]
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8
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Spinthaki A, Zerfaß C, Paulsen H, Hobe S, Demadis KD. Pleiotropic Role of Recombinant Silaffin-Like Cationic Polypeptide P5S3: Peptide-Induced Silicic Acid Stabilization, Silica Formation and Inhibition of Silica Dissolution. ChemistrySelect 2016. [DOI: 10.1002/slct.201601086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Argyro Spinthaki
- Crystal Engineering, Growth and Design Laboratory; Department of Chemistry; University of Crete; Voutes Campus, Heraklion Crete 71003 Greece
| | - Christian Zerfaß
- Department of Biology; Institute of General Botany; University of Mainz; Johannes-von-Müllerweg 6 55099 Mainz Germany
- Graduate School Materials Science in Mainz; University of Mainz, Staudingerweg 9, 55128 Mainz, Germany
| | - Harald Paulsen
- Department of Biology; Institute of General Botany; University of Mainz; Johannes-von-Müllerweg 6 55099 Mainz Germany
| | - Stephan Hobe
- Department of Biology; Institute of General Botany; University of Mainz; Johannes-von-Müllerweg 6 55099 Mainz Germany
| | - Konstantinos D. Demadis
- Crystal Engineering, Growth and Design Laboratory; Department of Chemistry; University of Crete; Voutes Campus, Heraklion Crete 71003 Greece
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9
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Marron AO, Ratcliffe S, Wheeler GL, Goldstein RE, King N, Not F, de Vargas C, Richter DJ. The Evolution of Silicon Transport in Eukaryotes. Mol Biol Evol 2016; 33:3226-3248. [PMID: 27729397 PMCID: PMC5100055 DOI: 10.1093/molbev/msw209] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Biosilicification (the formation of biological structures from silica) occurs in diverse eukaryotic lineages, plays a major role in global biogeochemical cycles, and has significant biotechnological applications. Silicon (Si) uptake is crucial for biosilicification, yet the evolutionary history of the transporters involved remains poorly known. Recent evidence suggests that the SIT family of Si transporters, initially identified in diatoms, may be widely distributed, with an extended family of related transporters (SIT-Ls) present in some nonsilicified organisms. Here, we identify SITs and SIT-Ls in a range of eukaryotes, including major silicified lineages (radiolarians and chrysophytes) and also bacterial SIT-Ls. Our evidence suggests that the symmetrical 10-transmembrane-domain SIT structure has independently evolved multiple times via duplication and fusion of 5-transmembrane-domain SIT-Ls. We also identify a second gene family, similar to the active Si transporter Lsi2, that is broadly distributed amongst siliceous and nonsiliceous eukaryotes. Our analyses resolve a distinct group of Lsi2-like genes, including plant and diatom Si-responsive genes, and sequences unique to siliceous sponges and choanoflagellates. The SIT/SIT-L and Lsi2 transporter families likely contribute to biosilicification in diverse lineages, indicating an ancient role for Si transport in eukaryotes. We propose that these Si transporters may have arisen initially to prevent Si toxicity in the high Si Precambrian oceans, with subsequent biologically induced reductions in Si concentrations of Phanerozoic seas leading to widespread losses of SIT, SIT-L, and Lsi2-like genes in diverse lineages. Thus, the origin and diversification of two independent Si transporter families both drove and were driven by ancient ocean Si levels.
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Affiliation(s)
- Alan O Marron
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge, United Kingdom .,Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Sarah Ratcliffe
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, United Kingdom
| | - Glen L Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, Devon, United Kingdom
| | - Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Nicole King
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA
| | - Fabrice Not
- CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris 06, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France
| | - Colomban de Vargas
- CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris 06, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France
| | - Daniel J Richter
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA.,CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris 06, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France
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10
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Durkin CA, Koester JA, Bender SJ, Armbrust EV. The evolution of silicon transporters in diatoms. JOURNAL OF PHYCOLOGY 2016; 52:716-731. [PMID: 27335204 PMCID: PMC5129515 DOI: 10.1111/jpy.12441] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/21/2016] [Indexed: 05/06/2023]
Abstract
Diatoms are highly productive single-celled algae that form an intricately patterned silica cell wall after every cell division. They take up and utilize silicic acid from seawater via silicon transporter (SIT) proteins. This study examined the evolution of the SIT gene family to identify potential genetic adaptations that enable diatoms to thrive in the modern ocean. By searching for sequence homologs in available databases, the diversity of organisms found to encode SITs increased substantially and included all major diatom lineages and other algal protists. A bacterial-encoded gene with homology to SIT sequences was also identified, suggesting that a lateral gene transfer event occurred between bacterial and protist lineages. In diatoms, the SIT genes diverged and diversified to produce five distinct clades. The most basal SIT clades were widely distributed across diatom lineages, while the more derived clades were lineage-specific, which together produced a distinct repertoire of SIT types among major diatom lineages. Differences in the predicted protein functional domains encoded among SIT clades suggest that the divergence of clades resulted in functional diversification among SITs. Both laboratory cultures and natural communities changed transcription of each SIT clade in response to experimental or environmental growth conditions, with distinct transcriptional patterns observed among clades. Together, these data suggest that the diversification of SITs within diatoms led to specialized adaptations among diatoms lineages, and perhaps their dominant ability to take up silicic acid from seawater in diverse environmental conditions.
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Affiliation(s)
- Colleen A. Durkin
- Moss Landing Marine Laboratories8272 Moss Landing RoadMoss LandingCalifornia95039USA
| | - Julie A. Koester
- Department of Biology and Marine BiologyUniversity of North Carolina WilmingtonWilmingtonNorth Carolina28403USA
| | - Sara J. Bender
- Marine Chemistry and GeochemistryWoods Hole Oceanographic InstitutionWoods HoleMassachusetts02543USA
- Present address: The Gordon and Betty Moore FoundationPalo AltoCalifornia94304USA
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11
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Knight MJ, Senior L, Nancolas B, Ratcliffe S, Curnow P. Direct evidence of the molecular basis for biological silicon transport. Nat Commun 2016; 7:11926. [PMID: 27305972 PMCID: PMC4912633 DOI: 10.1038/ncomms11926] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/11/2016] [Indexed: 12/19/2022] Open
Abstract
Diatoms are an important group of eukaryotic algae with a curious evolutionary innovation: they sheath themselves in a cell wall made largely of silica. The cellular machinery responsible for silicification includes a family of membrane permeases that recognize and actively transport the soluble precursor of biosilica, silicic acid. However, the molecular basis of silicic acid transport remains obscure. Here, we identify experimentally tractable diatom silicic acid transporter (SIT) homologues and study their structure and function in vitro, enabled by the development of a new fluorescence method for studying substrate transport kinetics. We show that recombinant SITs are Na+/silicic acid symporters with a 1:1 protein: substrate stoichiometry and KM for silicic acid of 20 μM. Protein mutagenesis supports the long-standing hypothesis that four conserved GXQ amino acid motifs are important in SIT function. This marks a step towards a detailed understanding of silicon transport with implications for biogeochemistry and bioinspired materials. Diatoms sheath themselves in a self-made casing of silica, which requires the function of silicic acid transporters. Here, the authors identify versions of these transporters that are experimentally tractable, and develop a fluorescence method to study silicic acid transport in vitro.
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Affiliation(s)
- Michael J Knight
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Laura Senior
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Bethany Nancolas
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Sarah Ratcliffe
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Paul Curnow
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.,BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
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12
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Hildebrand M, Lerch SJL. Diatom silica biomineralization: Parallel development of approaches and understanding. Semin Cell Dev Biol 2015; 46:27-35. [PMID: 26256954 DOI: 10.1016/j.semcdb.2015.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/03/2015] [Accepted: 06/28/2015] [Indexed: 10/23/2022]
Abstract
Diatom silica cell walls present an intriguing application of biomineralization in a single celled organism. The ability of diatoms to make an enormous variety of silica structures on the nano- to micro-scale is unparalleled in nature. The process is a whole-cell endeavor, involving diverse cellular components that coordinate "bottom up" and "top down" structure formation processes to reproducibly convert genetic information into physical structure. The study of silicification has been similarly all encompassing, involving the application of diverse analytical techniques to examine different aspects of the process. This review highlights the application of different approaches used to study silicification and the insights they have provided, and documents the progress that has been made. The current status offers the possibility of major breakthroughs in our understanding, by enabling a more widespread identification of genes involved, and direct testing of the role these genes play by genetic manipulation.
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Affiliation(s)
- Mark Hildebrand
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, USA.
| | - Sarah J L Lerch
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, USA
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13
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Sahebi M, Hanafi MM, Siti Nor Akmar A, Rafii MY, Azizi P, Tengoua FF, Nurul Mayzaitul Azwa J, Shabanimofrad M. Importance of silicon and mechanisms of biosilica formation in plants. BIOMED RESEARCH INTERNATIONAL 2015; 2015:396010. [PMID: 25685787 PMCID: PMC4317640 DOI: 10.1155/2015/396010] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 12/18/2014] [Accepted: 12/23/2014] [Indexed: 11/17/2022]
Abstract
Silicon (Si) is one of the most prevalent macroelements, performing an essential function in healing plants in response to environmental stresses. The purpose of using Si is to induce resistance to distinct stresses, diseases, and pathogens. Additionally, Si can improve the condition of soils, which contain toxic levels of heavy metals along with other chemical elements. Silicon minimizes toxicity of Fe, Al, and Mn, increases the availability of P, and enhances drought along with salt tolerance in plants through the formation of silicified tissues in plants. However, the concentration of Si depends on the plants genotype and organisms. Hence, the physiological mechanisms and metabolic activities of plants may be affected by Si application. Peptides as well as amino acids can effectively create polysilicic species through interactions with different species of silicate inside solution. The carboxylic acid and the alcohol groups of serine and asparagine tend not to engage in any significant role in polysilicates formation, but the hydroxyl group side chain can be involved in the formation of hydrogen bond with Si(OH)4. The mechanisms and trend of Si absorption are different between plant species. Furthermore, the transportation of Si requires an energy mechanism; thus, low temperatures and metabolic repressors inhibit Si transportation.
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Affiliation(s)
- Mahbod Sahebi
- Laboratory of Plantation Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Mohamed M. Hanafi
- Laboratory of Plantation Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Department of Land Management, Faculty of Agriculture, 43400 Serdang, Selangor, Malaysia
| | - Abdullah Siti Nor Akmar
- Laboratory of Plantation Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Mohd Y. Rafii
- Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Parisa Azizi
- Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - F. F. Tengoua
- Laboratory of Plantation Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Jamaludin Nurul Mayzaitul Azwa
- Laboratory of Plantation Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - M. Shabanimofrad
- Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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Lantez V, Nikolaidis I, Rechenmann M, Vernet T, Noirclerc-Savoye M. Rapid automated detergent screening for the solubilization and purification of membrane proteins and complexes. Eng Life Sci 2015. [DOI: 10.1002/elsc.201400187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Violaine Lantez
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
| | - Ioulia Nikolaidis
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
- Department of Biochemistry of Membranes; Bijvoet Center for Biomolecular Research, Utrecht University; The Netherlands
| | - Mathias Rechenmann
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
| | - Thierry Vernet
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
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15
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Shrestha RP, Hildebrand M. Evidence for a regulatory role of diatom silicon transporters in cellular silicon responses. EUKARYOTIC CELL 2015; 14:29-40. [PMID: 25380754 PMCID: PMC4279021 DOI: 10.1128/ec.00209-14] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/03/2014] [Indexed: 01/19/2023]
Abstract
The utilization of silicon by diatoms has both global and small-scale implications, from oceanic primary productivity to nanotechnological applications of their silica cell walls. The sensing and transport of silicic acid are key aspects of understanding diatom silicon utilization. At low silicic acid concentrations (<30 μM), transport mainly occurs through silicic acid transport proteins (SITs), and at higher concentrations it occurs through diffusion. Previous analyses of the SITs were done either in heterologous systems or without a distinction between individual SITs. In the present study, we examined individual SITs in Thalassiosira pseudonana in terms of transcript and protein abundance in response to different silicic acid regimes and examined knockdown lines to evaluate the role of the SITs in transport, silica incorporation, and lipid accumulation resulting from silicon starvation. SIT1 and SIT2 were localized in the plasma membrane, and protein levels were generally inversely correlated with cellular silicon needs, with a distinct response being found when the two SITs were compared. We developed highly effective approaches for RNA interference and antisense knockdowns, the first such approaches developed for a centric diatom. SIT knockdown differentially affected the uptake of silicon and the incorporation of silicic acid and resulted in the induction of lipid accumulation under silicon starvation conditions far earlier than in the wild-type cells, suggesting that the cells were artificially sensing silicon limitation. The data suggest that the transport role of the SITs is relatively minor under conditions with sufficient silicic acid. Their primary role is to sense silicic acid levels to evaluate whether the cell can proceed with its cell wall formation and division processes.
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Affiliation(s)
- Roshan P Shrestha
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - Mark Hildebrand
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
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16
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Javaheri N, Dries R, Kaandorp J. Understanding the sub-cellular dynamics of silicon transportation and synthesis in diatoms using population-level data and computational optimization. PLoS Comput Biol 2014; 10:e1003687. [PMID: 24945622 PMCID: PMC4063665 DOI: 10.1371/journal.pcbi.1003687] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 05/09/2014] [Indexed: 01/10/2023] Open
Abstract
Controlled synthesis of silicon is a major challenge in nanotechnology and material science. Diatoms, the unicellular algae, are an inspiring example of silica biosynthesis, producing complex and delicate nano-structures. This happens in several cell compartments, including cytoplasm and silica deposition vesicle (SDV). Considering the low concentration of silicic acid in oceans, cells have developed silicon transporter proteins (SIT). Moreover, cells change the level of active SITs during one cell cycle, likely as a response to the level of external nutrients and internal deposition rates. Despite this topic being of fundamental interest, the intracellular dynamics of nutrients and cell regulation strategies remain poorly understood. One reason is the difficulties in measurements and manipulation of these mechanisms at such small scales, and even when possible, data often contain large errors. Therefore, using computational techniques seems inevitable. We have constructed a mathematical model for silicon dynamics in the diatom Thalassiosira pseudonana in four compartments: external environment, cytoplasm, SDV and deposited silica. The model builds on mass conservation and Michaelis-Menten kinetics as mass transport equations. In order to find the free parameters of the model from sparse, noisy experimental data, an optimization technique (global and local search), together with enzyme related penalty terms, has been applied. We have connected population-level data to individual-cell-level quantities including the effect of early division of non-synchronized cells. Our model is robust, proven by sensitivity and perturbation analysis, and predicts dynamics of intracellular nutrients and enzymes in different compartments. The model produces different uptake regimes, previously recognized as surge, externally-controlled and internally-controlled uptakes. Finally, we imposed a flux of SITs to the model and compared it with previous classical kinetics. The model introduced can be generalized in order to analyze different biomineralizing organisms and to test different chemical pathways only by switching the system of mass transport equations.
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Affiliation(s)
- Narjes Javaheri
- Section Computational Science, University of Amsterdam, Amsterdam, The Netherlands
| | - Roland Dries
- Section Computational Science, University of Amsterdam, Amsterdam, The Netherlands
- FOM Institute AMOLF, Amsterdam, The Netherlands
| | - Jaap Kaandorp
- Section Computational Science, University of Amsterdam, Amsterdam, The Netherlands
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17
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Preari M, Spinde K, Lazic J, Brunner E, Demadis KD. Bioinspired Insights into Silicic Acid Stabilization Mechanisms: The Dominant Role of Polyethylene Glycol-Induced Hydrogen Bonding. J Am Chem Soc 2014; 136:4236-44. [DOI: 10.1021/ja411822s] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Melina Preari
- Crystal
Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Heraklion, Crete, GR-71003, Greece
| | - Katrin Spinde
- Fachrichtung
Chemie und Lebensmittelchemie, Bioanalytische Chemie, Technische Universität Dresden, 01062 Dresden, Germany
| | - Joëlle Lazic
- Fachrichtung
Chemie und Lebensmittelchemie, Bioanalytische Chemie, Technische Universität Dresden, 01062 Dresden, Germany
| | - Eike Brunner
- Fachrichtung
Chemie und Lebensmittelchemie, Bioanalytische Chemie, Technische Universität Dresden, 01062 Dresden, Germany
| | - Konstantinos D. Demadis
- Crystal
Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Heraklion, Crete, GR-71003, Greece
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18
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Annenkov VV, Basharina TN, Danilovtseva EN, Grachev MA. Putative silicon transport vesicles in the cytoplasm of the diatom Synedra acus during surge uptake of silicon. PROTOPLASMA 2013; 250:1147-1155. [PMID: 23525742 DOI: 10.1007/s00709-013-0495-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 03/11/2013] [Indexed: 06/02/2023]
Abstract
We studied the growth of the araphid pennate diatom Synedra acus subsp. radians (Kützing) Skabichevskii using a fluorescent dye N(1),N(3)-dimethyl-N(1)-(7-nitro-2,1,3-benzoxadiazol-4-yl)propane-1,3-diamine (NBD-N2), which stains growing siliceous frustules but does not stain other subcellular organelles. We used a clonal culture of S. acus that was synchronized by silicon starvation. Epifluorescence microscopy was performed in two different ways with cells stained by the addition of silicic acid and the dye. Individual cells immobilized on glass were observed during the first 15-20 min following the replenishment of silicic acid after silicon starvation. Alternatively, we examined cells of a batch culture at time intervals during 36 h after the replenishment of silicic acid using fluorescence and confocal microscopy. The addition of silicic acid and NBD-N2 resulted in the rapid (1-2 min) formation of several dozen green fluorescent submicrometer particles (GFSPs) in the cytoplasm, which was accompanied by the accumulation of fluorescent silica inside silica deposition vesicles (SDVs) along their full length. In 5-15 min, GFSPs disappeared from the cytoplasm. Mature siliceous valves were formed within the SDVs during the subsequent 14-16 h. In the next 8-10 h, GFSPs appeared again in the cytoplasm of daughter cells. The data obtained confirm observations about the two-stage mechanism of silicon assimilation, which includes rapid silicon uptake (surge uptake) followed by slow silica deposition. It is likely that the observed GFSPs are silicon transport vesicles, which were first proposed by Schmid and Schulz in (Protoplasma 100:267-288, 1979).
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Affiliation(s)
- Vadim V Annenkov
- Limnological Institute, Siberian Branch of Russian Academy of Sciences, 3, Ulan-Batorskaya St, P.O. Box 278, Irkutsk, 664033, Russia,
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19
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Pollock NL, McDevitt CA, Collins R, Niesten PHM, Prince S, Kerr ID, Ford RC, Callaghan R. Improving the stability and function of purified ABCB1 and ABCA4: the influence of membrane lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:134-47. [PMID: 24036079 DOI: 10.1016/j.bbamem.2013.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/27/2013] [Accepted: 09/03/2013] [Indexed: 12/17/2022]
Abstract
ATP Binding Cassette (ABC) transporters play prominent roles in numerous cellular processes and many have been implicated in human diseases. Unfortunately, detailed mechanistic information on the majority of ABC transporters has not yet been elucidated. The slow rate of progress of molecular and high resolution structural studies may be attributed to the difficulty in the investigation of integral membrane proteins. These difficulties include the expression of functional, non-aggregated protein in heterologous systems. Furthermore, the extraction of membrane proteins from source material remains a major bottle-neck in the process since there are relatively few guidelines for selection of an appropriate detergent to achieve optimal extraction. Whilst affinity tag strategies have simplified the purification of membrane proteins; many challenges remain. For example, the chromatographic process and associated steps can rapidly lead to functional inactivation, random aggregation, or even precipitation of the target protein. Furthermore, optimisation of high yield and purity, does not guarantee successful structure determination. Based on this series of potential issues, any investigation into structure-function of membrane proteins requires a systematic evaluation of preparation quality. In particular, the evaluation should focus on function, homogeneity and mono-dispersity. The present investigation provides a detailed assessment of the quality of purified ATP Binding Cassette (ABC) transporters; namely ABCB1 (P-gp) and ABCA4 (ABCR). A number of suggestions are provided to facilitate the production of functional, homogeneous and mono-disperse preparations using the insect cell expression system. Finally, the ABCA4 samples have been used to provide structural insights into this essential photo-receptor cell protein.
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Affiliation(s)
- Naomi L Pollock
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
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20
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Marron AO, Alston MJ, Heavens D, Akam M, Caccamo M, Holland PWH, Walker G. A family of diatom-like silicon transporters in the siliceous loricate choanoflagellates. Proc Biol Sci 2013; 280:20122543. [PMID: 23407828 PMCID: PMC3574361 DOI: 10.1098/rspb.2012.2543] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 01/17/2013] [Indexed: 11/12/2022] Open
Abstract
Biosilicification is widespread across the eukaryotes and requires concentration of silicon in intracellular vesicles. Knowledge of the molecular mechanisms underlying this process remains limited, with unrelated silicon-transporting proteins found in the eukaryotic clades previously studied. Here, we report the identification of silicon transporter (SIT)-type genes from the siliceous loricate choanoflagellates Stephanoeca diplocostata and Diaphanoeca grandis. Until now, the SIT gene family has been identified only in diatoms and other siliceous stramenopiles, which are distantly related to choanoflagellates among the eukaryotes. This is the first evidence of similarity between SITs from different eukaryotic supergroups. Phylogenetic analysis indicates that choanoflagellate and stramenopile SITs form distinct monophyletic groups. The absence of putative SIT genes in any other eukaryotic groups, including non-siliceous choanoflagellates, leads us to propose that SIT genes underwent a lateral gene transfer event between stramenopiles and loricate choanoflagellates. We suggest that the incorporation of a foreign SIT gene into the stramenopile or choanoflagellate genome resulted in a major metabolic change: the acquisition of biomineralized silica structures. This hypothesis implies that biosilicification has evolved multiple times independently in the eukaryotes, and paves the way for a better understanding of the biochemical basis of silicon transport through identification of conserved sequence motifs.
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Affiliation(s)
- Alan O Marron
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
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21
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Otzen D. The role of proteins in biosilicification. SCIENTIFICA 2012; 2012:867562. [PMID: 24278750 PMCID: PMC3820600 DOI: 10.6064/2012/867562] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 09/24/2012] [Indexed: 05/19/2023]
Abstract
Although the use of silicon dioxide (silica) as a constituent of living organisms is mainly restricted to diatoms and sponges, the ways in which this process is controlled by nature continue to inspire and fascinate. Both diatoms and sponges carry out biosilificiation using an organic matrix but they adopt very different strategies. Diatoms use small and heavily modified peptides called silaffins, where the most characteristic feature is a modulation of charge by attaching long chain polyamines (LCPAs) to lysine groups. Free LCPAs can also cooperate with silaffins. Sponges use the enzyme silicatein which is homologous to the cysteine protease cathepsin. Both classes of proteins form higher-order structures which act both as structural templates and mechanistic catalysts for the polycondensation reaction. In both cases, additional proteins are continuously being discovered which modulate the process further. This paper concentrates on the role of these proteins in the biosilification process as well as in various applications, highlighting areas where focus on specific protein properties may provide further insight. The field of biosilification is a crossroads of different disciplines, where insight into the energetics and mechanisms of molecular self-assembly combine with fundamental biology, complex multicomponent colloidal systems, and an impressive array of potential technological applications.
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Affiliation(s)
- Daniel Otzen
- Interdisciplinary Nanoscience Center (iNANO), Center for Insoluble Protein Structures (inSPIN), and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
- *Daniel Otzen:
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