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Knight B, Mondal R, Han N, Pietra NF, Hall BA, Edgar KJ, Vaissier Welborn V, Madsen LA, De Yoreo JJ, Dove PM. Kinetics of Calcite Nucleation onto Sulfated Chitosan Derivatives and Implications for Water-Polysaccharide Interactions during Crystallization of Sparingly Soluble Salts. CRYSTAL GROWTH & DESIGN 2024; 24:6338-6353. [PMID: 39131446 PMCID: PMC11311137 DOI: 10.1021/acs.cgd.4c00602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 08/13/2024]
Abstract
Anionic macromolecules are found at sites of CaCO3 biomineralization in diverse organisms, but their roles in crystallization are not well-understood. We prepared a series of sulfated chitosan derivatives with varied positions and degrees of sulfation, DS(SO3 -), and measured calcite nucleation rate onto these materials. Fitting the classical nucleation theory model to the kinetic data reveals the interfacial free energy of the calcite-polysaccharide-solution system, γnet, is lowest for nonsulfated controls and increases with DS(SO3 -). The kinetic prefactor also increases with DS(SO3 -). Simulations of Ca2+-H2O-chitosan systems show greater water structuring around sulfate groups compared to uncharged substituents, independent of sulfate location. Ca2+-SO3 - interactions are solvent-separated by distances that are inversely correlated with DS(SO3 -) of the polysaccharide. The simulations also predict SO3 - and NH3 + groups affect the solvation waters and HCO3 - ions associated with Ca2+. Integrating the experimental and computational evidence suggests sulfate groups influence nucleation by increasing the difficulty of displacing near-surface water, thereby increasing γnet. By correlating γnet and net charge per monosaccharide for diverse polysaccharides, we suggest the solvent-separated interactions of functional groups with Ca2+ influence thermodynamic and kinetic components to crystallization by similar solvent-dominated processes. The findings reiterate the importance of establishing water structure and properties at macromolecule-solution interfaces.
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Affiliation(s)
- Brenna
M. Knight
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Ronnie Mondal
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Nizhou Han
- Department
of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Nicholas F. Pietra
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Brady A. Hall
- GlycoMIP, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Kevin J. Edgar
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Sustainable Biomaterials, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Valerie Vaissier Welborn
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Louis A. Madsen
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - James J. De Yoreo
- Physical
Sciences Division, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Department
of Materials Science and Engineering, University
of Washington, Seattle, Washington 98195, United States
| | - Patricia M. Dove
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Materials Science and Engineering, Virginia
Tech, Blacksburg, Virginia 24061, United States
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2
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Carter MS, Tuttle MJ, Mancini JA, Martineau R, Hung CS, Gupta MK. Microbially Induced Calcium Carbonate Precipitation by Sporosarcina pasteurii: a Case Study in Optimizing Biological CaCO 3 Precipitation. Appl Environ Microbiol 2023; 89:e0179422. [PMID: 37439668 PMCID: PMC10467343 DOI: 10.1128/aem.01794-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023] Open
Abstract
Current production of traditional concrete requires enormous energy investment that accounts for approximately 5 to 8% of the world's annual CO2 production. Biocement is a building material that is already in industrial use and has the potential to rival traditional concrete as a more convenient and more environmentally friendly alternative. Biocement relies on biological structures (enzymes, cells, and/or cellular superstructures) to mineralize and bind particles in aggregate materials (e.g., sand and soil particles). Sporosarcina pasteurii is a workhorse organism for biocementation, but most research to date has focused on S. pasteurii as a building material rather than a biological system. In this review, we synthesize available materials science, microbiology, biochemistry, and cell biology evidence regarding biological CaCO3 precipitation and the role of microbes in microbially induced calcium carbonate precipitation (MICP) with a focus on S. pasteurii. Based on the available information, we provide a model that describes the molecular and cellular processes involved in converting feedstock material (urea and Ca2+) into cement. The model provides a foundational framework that we use to highlight particular targets for researchers as they proceed into optimizing the biology of MICP for biocement production.
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Affiliation(s)
- Michael S. Carter
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Matthew J. Tuttle
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Joshua A. Mancini
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Rhett Martineau
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Chia-Suei Hung
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
| | - Maneesh K. Gupta
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
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3
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Li M, Tang J, Yuan M, Huang B, Liu Y, Wei L, Han Y, Zhang X, Wang X, Yu G, Sang X, Fan N, Cai S, Zheng Y, Zhang M, Wang X. Outer fold is sole effective tissue among three mantle folds with regard to oyster shell colour. Int J Biol Macromol 2023; 241:124655. [PMID: 37121412 DOI: 10.1016/j.ijbiomac.2023.124655] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/21/2023] [Accepted: 04/24/2023] [Indexed: 05/02/2023]
Abstract
Molluscs constitute the second largest phylum of animals in the world, and shell colour is one of their most important phenotypic characteristics. In this study, we found among three folds on the mantle edge of oyster, only the outer fold had the same colour as the shell. Transcriptome and mantle cutting experiment indicated that the outer fold may be mainly reflected in chitin framework formation and biomineralisation. There were obvious differences in SEM structure and protein composition between the black and white shell periostraca. The black shell periostraca had more proteins related to melanin biosynthesis and chitin binding. Additionally, we identified an uncharacterized protein gene (named as CgCBP) ultra-highly expressed only in the black outer fold and confirmed its function of chitin-binding and CaCO3 precipitation promoting. RNAi also indicated that CgCBP knockdown could change the structure of shell periostracum and reduce shell pigmentation. All these results suggest that the mantle outer fold plays multiple key roles in shell periostraca bioprocessing, and shell periostracum structure affected by chitin-binding protein is functionally correlated with shell pigmentation. The investigation of oyster shell periostracum structure and shell colour will provide a better understanding in pigmentation during biological mineralisation in molluscs.
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Affiliation(s)
- Mai Li
- School of Agriculture, Ludong University, Yantai, China
| | - Juyan Tang
- School of Agriculture, Ludong University, Yantai, China
| | | | - Baoyu Huang
- School of Agriculture, Ludong University, Yantai, China
| | - Yaqiong Liu
- School of Agriculture, Ludong University, Yantai, China
| | - Lei Wei
- School of Agriculture, Ludong University, Yantai, China
| | - Yijing Han
- School of Agriculture, Ludong University, Yantai, China
| | - Xuekai Zhang
- School of Agriculture, Ludong University, Yantai, China
| | - Xiaona Wang
- School of Agriculture, Ludong University, Yantai, China
| | - Guoxu Yu
- Changdao National Marine Park Management Center, Yantai, China
| | - Xiuxiu Sang
- School of Agriculture, Ludong University, Yantai, China
| | - Nini Fan
- Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai, China
| | - Shuai Cai
- Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai, China
| | - Yanxin Zheng
- Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai, China
| | - Meiwei Zhang
- School of Agriculture, Ludong University, Yantai, China.
| | - Xiaotong Wang
- School of Agriculture, Ludong University, Yantai, China.
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4
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Knight BM, Edgar KJ, De Yoreo JJ, Dove PM. Chitosan as a Canvas for Studies of Macromolecular Controls on CaCO 3 Biological Crystallization. Biomacromolecules 2023; 24:1078-1102. [PMID: 36853173 DOI: 10.1021/acs.biomac.2c01394] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
A mechanistic understanding of how macromolecules, typically as an organic matrix, nucleate and grow crystals to produce functional biomineral structures remains elusive. Advances in structural biology indicate that polysaccharides (e.g., chitin) and negatively charged proteoglycans (due to carboxyl, sulfate, and phosphate groups) are ubiquitous in biocrystallization settings and play greater roles than currently recognized. This review highlights studies of CaCO3 crystallization onto chitinous materials and demonstrates that a broader understanding of macromolecular controls on mineralization has not emerged. With recent advances in biopolymer chemistry, it is now possible to prepare chitosan-based hydrogels with tailored functional group compositions. By deploying these characterized compounds in hypothesis-based studies of nucleation rate, quantitative relationships between energy barrier to crystallization, macromolecule composition, and solvent structuring can be determined. This foundational knowledge will help researchers understand composition-structure-function controls on mineralization in living systems and tune the designs of new materials for advanced applications.
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Affiliation(s)
- Brenna M Knight
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Kevin J Edgar
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - James J De Yoreo
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Patricia M Dove
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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5
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de Muizon CJ, Iandolo D, Nguyen DK, Al-Mourabit A, Rousseau M. Organic Matrix and Secondary Metabolites in Nacre. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:831-842. [PMID: 36057751 DOI: 10.1007/s10126-022-10145-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Nacre, also called mother-of-pearl, is a naturally occurring biomineral, largely studied by chemists, structural biologists, and physicists to understand its outstanding and diverse properties. Nacre is constituted of aragonite nanograins surrounded by organic matrix, and it has been established that the organic matrix is responsible for initiating and guiding the biomineralization process. The first challenge to study the organic matrix of nacre lays in its separation from the biomineral. Several extraction methods have been developed so far. They are categorized as either strong (e.g., decalcification) or soft (e.g., water, ethanol) and they allow specific extractions of targeted compounds. The structure of the nacreous organic matrix is complex, and it provides interesting clues to describe the mineralization process. Proteins, sugars, lipids, peptides, and other molecules have been identified and their role in mineralization investigated. Moreover, the organic matrix of nacre has shown interesting properties for human health. Several studies are investigating its activity on bone mineralization and its properties for skin care. In this review, we focus on the organic constituents, as lipids, sugars, and small metabolites which are less studied since present in small quantities.
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Affiliation(s)
- Capucine Jourdain de Muizon
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- STANSEA, Saint-Étienne, France
| | - Donata Iandolo
- UMR5510 MATEIS, CNRS, University of Lyon, INSA-Lyon, Lyon, France
- U1059 INSERM - SAINBIOSE (SAnté INgéniérie BIOlogie St-Etienne) Campus Santé Innovation, Université Jean Monnet, Saint-Priest-en-Jarez, France
| | - Dung Kim Nguyen
- U1059 INSERM - SAINBIOSE (SAnté INgéniérie BIOlogie St-Etienne) Campus Santé Innovation, Université Jean Monnet, Saint-Priest-en-Jarez, France
| | - Ali Al-Mourabit
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Marthe Rousseau
- UMR5510 MATEIS, CNRS, University of Lyon, INSA-Lyon, Lyon, France.
- U1059 INSERM - SAINBIOSE (SAnté INgéniérie BIOlogie St-Etienne) Campus Santé Innovation, Université Jean Monnet, Saint-Priest-en-Jarez, France.
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6
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Rivera-Pérez C, Arroyo-Loranca RG, Hernández-Saavedra NY. An acidic protein, Hf15, from Haliotis fulgens involved in biomineralization. Comp Biochem Physiol A Mol Integr Physiol 2022; 272:111276. [PMID: 35853523 DOI: 10.1016/j.cbpa.2022.111276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/20/2022] [Accepted: 07/13/2022] [Indexed: 11/16/2022]
Abstract
Biomineralization leads to the hardening of mineralized materials, such as the shell of Mollusk, to fulfill a wide range of functions, such as (but not limited to) skeletal support, protection of the soft tissues, navigation, etc. The study of the proteins responsible for this process, shell matrix proteins (SMPs), allows addressing questions related to structure-function relationship and to the mechanism of mineral formation, which is limited in gastropod species. In this study, a low molecular weight protein was isolated from the insoluble fraction after decalcification with acetic acid of the shell of Haliotis fulgens and, named Hf15. The unglycosylated protein has a theoretical molecular weight of 15 kDa, it possesses calcium and chiting binding properties. Hf15 can precipitate calcium carbonate in vitro in presence of different salts. Analysis by LC-MS of the five peptide sequences of Hf15 generated by trypsinization revealed that two peptides displayed homology to an uncharacterized protein 3-like from Haliotis rufescens, Haliotis asinia and H. sorenseni. The results obtained indicated that Hf15 is a novel SMP involved in shell mineralization in Haliotis fulgens.
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Affiliation(s)
| | - Raquel G Arroyo-Loranca
- Fisheries Ecology, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Baja California Sur, Mexico
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7
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Rivera-Pérez C, Hernández-Saavedra NY. Review: Post-translational modifications of marine shell matrix proteins. Comp Biochem Physiol B Biochem Mol Biol 2021; 256:110641. [PMID: 34182126 DOI: 10.1016/j.cbpb.2021.110641] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/13/2021] [Accepted: 06/22/2021] [Indexed: 11/18/2022]
Abstract
Shell matrix proteins (SMPs) are key components for the Mollusk shell biomineralization. SMPs function has been hypothesized in several proteins by bioinformatics analysis, and through in vitro crystallization assays. However, studies of the post-translational modifications (PTMs) of SMPs, which contribute to their structure and the function, are limited. This review provides the current status of the SMPs with the most common PTMs described (glycosylation, phosphorylation, and disulfide bond formation) and their role in shell biomineralization. Also, recent studies based on recombinant production of SMPs are discussed. Finally, recommendations for the study of SMPs and their PTMs are provided. The review showed that PTMs are widely distributed in SMPs, and their presence on SMPs may contribute to the modulation of their activity in some SMPs, contributing to the crystal growth formation and differentiation through different mechanisms, however, in a few cases the lack of the PTMs do not alter their inherent function.
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Affiliation(s)
- Crisalejandra Rivera-Pérez
- CONACYT, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Baja California Sur, Mexico.
| | - Norma Y Hernández-Saavedra
- Molecular Genetics Laboratory, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz 23096, Baja California Sur, Mexico
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8
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Jackson DJ. Mantle Modularity Underlies the Plasticity of the Molluscan Shell: Supporting Data From Cepaea nemoralis. Front Genet 2021; 12:622400. [PMID: 33613640 PMCID: PMC7894901 DOI: 10.3389/fgene.2021.622400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/04/2021] [Indexed: 01/18/2023] Open
Abstract
Molluscs have evolved the capacity to fabricate a wide variety of shells over their 540+ million-year history. While modern sequencing and proteomic technologies continue to expand the catalog of molluscan shell-forming proteins, a complete functional understanding of how any mollusc constructs its shell remains an ambitious goal. This lack of understanding also constrains our understanding of how evolution has generated a plethora of molluscan shell morphologies. Taking advantage of a previous expression atlas for shell-forming genes in Lymnaea stagnalis, I have characterized the spatial expression patterns of seven shell-forming genes in the terrestrial gastropod Cepaea nemoralis, with the aim of comparing and contrasting their expression patterns between the two species. Four of these genes were selected from a previous proteomic screen of the C. nemoralis shell, two were targeted by bioinformatics criteria designed to identify likely shell-forming gene products, and the final one was a clear homolog of a peroxidase sequence in the L. stagnalis dataset. While the spatial expression patterns of all seven C. nemoralis genes could be recognized as falling into distinct zones within the mantle tissue similar to those established in L. stagnalis, some zones have apparently been modified. These similarities and differences hint at a modularity to the molluscan mantle that may provide a mechanistic explanation as to how evolution has efficiently generated a diversity of molluscan shells.
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Affiliation(s)
- Daniel J Jackson
- Department of Geobiology, Georg-August University of Göttingen, Göttingen, Germany
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9
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Diversified Biomineralization Roles of Pteria penguin Pearl Shell Lectins as Matrix Proteins. Int J Mol Sci 2021; 22:ijms22031081. [PMID: 33499178 PMCID: PMC7865697 DOI: 10.3390/ijms22031081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/13/2021] [Accepted: 01/19/2021] [Indexed: 12/03/2022] Open
Abstract
Previously, we isolated jacalin-related lectins termed PPL2, PPL3 (PPL3A, 3B and 3C) and PPL4 from the mantle secretory fluid of Pteria penguin (Mabe) pearl shell. They showed the sequence homology with the plant lectin family, jacalin-related β-prism fold lectins (JRLs). While PPL3s and PPL4 shared only 35%–50% homology to PPL2A, respectively, they exhibited unique carbohydrate binding properties based on the multiple glycan-binding profiling data sets from frontal affinity chromatography analysis. In this paper, we investigated biomineralization properties of these lectins and compared their biomineral functions. It was found that these lectins showed different effects on CaCO3 crystalization, respectively, although PPL3 and PPL2A showed similar carbohydrate binding specificities. PPL3 suppressed the crystal growth of CaCO3 calcite, while PPL2A increased the number of contact polycrystalline calcite composed of more than one crystal with various orientations. Furthermore, PPL4 alone showed no effect on CaCO3 crystalization; however, PPL4 regulated the size of crystals collaborated with N-acetyl-D-glucosamine and chitin oligomer, which are specific in recognizing carbohydrates for PPL4. These observations highlight the unique functions and molecular evolution of this lectin family involved in the mollusk shell formation.
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10
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Rivera-Perez C, Flores-Sánchez IA, Ojeda Ramírez de Areyano JJ, Rojas Posadas DI, Hernández-Saavedra NY. A shell matrix protein of Pinctada mazatlanica produces nacre platelets in vitro. Sci Rep 2020; 10:20201. [PMID: 33214608 PMCID: PMC7677314 DOI: 10.1038/s41598-020-77320-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/09/2020] [Indexed: 11/09/2022] Open
Abstract
AbstractNacre is the main component of the pearl oyster shells and it is synthesized by specialized soluble and insoluble shell matrix proteins. Insoluble proteins from the decalcification of the shell are the less studied proteins due to the technical problems to isolate them from the organic matrix. In this study, an insoluble shell matrix protein from Pinctada mazatlanica, pearlin (Pmaz-pearlin), was successfully cloned from the mantle tissue, and the native protein isolated from the shell was functionally characterized. The full coding sequence of Pmaz-pearlin mRNA consists of 423 base pairs, which encode to a 16.3 kDa pearlin. Analysis of the deduced amino acid sequence revealed that Pmaz-pearlin contained four acidic regions, an NG repeat domain, and Cys conserved residues, the latter potentially forms four disulfide bridges which might stabilize the protein structure. The isolated protein from the shell is a glycoprotein of ~ 16.74 kDa which can produce aragonite and calcite crystals in vitro. Our results show that Pmaz-pearlin is a well-conserved protein involved in nacre layer growth, which produces calcite crystals in the presence of CaCl2, aragonite crystal polymorphs with a hexagonal structure in the presence of MgCl2, and needle-like crystal structure polymorphs in the presence of CaCO3 The identity of the crystals was confirmed using RAMAN analyses.
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