title: Dual Roles of the Lysine-Rich Matrix Protein (KRMP)-3 in Shell Formation of Pearl Oyster, Pinctada fucata.
abstract: Matrix proteins play important roles in shell formation. Our group firstly isolated three cDNAs encoding lysine-rich matrix protein from Pinctada fucata in 2006. However, the functions of KRMPs are not fully understood. In addition, KRMPs contain two functional domains, the basic domain and the Gly/Tyr domain respectively. Based on the modular organization, the roles of their two domains were poorly characterized. Furthermore, KRMPs were then reported in other two species, P. maxima and P. margaritifera, which indicated that KRMPs might be very important for shell formation. In this study, the characterization and function of KRMP-3 and its two functional domains were studied in vitro through purification of recombinant glutathione S-transferase tagged KRMP-3 and two KRMP-3 deletion mutants. Western blot and immunofluorescence revealed that native KRMP-3 existed in the EDTA-insoluble matrix of the prismatic layer and was located in the organic sheet and the prismatic sheath. Recombinant KRMP-3 (rKRMP-3) bound tightly to chitin and this binding capacity was duo to the Gly/Tyr-rich region. rKRMP-3 inhibited the precipitation of CaCO3, affected the crystal morphology of calcite and inhibited the growth of aragonite in vitro, which was almost entirely attributed to the lysine-rich region. The results present direct evidence of the roles of KRMP-3 in shell biomineralization. The functional rBR region was found to participate in the growth control of crystals and the rGYR region was responsible to bind to chitin.
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Liang
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Guangrui
authors.initials: G
authors.lastname: Xu
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xie
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Ilsun
authors.initials: I
authors.lastname: Lee
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Xiang
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Hongzhong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Guiyou
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China; Protein Science Laboratory of the Ministry of Education, Tsinghua University, Beijing, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Xie
authors.affiliation: Institute of Marine Biotechnology, Collaborative Innovation Center of Deep Sea Biology, School of Life Sciences, Tsinghua University, Beijing, China; Protein Science Laboratory of the Ministry of Education, Tsinghua University, Beijing, China.
authors.forename: Rongqing
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D060105:Animal Shells / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry; D011232:Chemical Precipitation; D002686:Chitin / Q000378:metabolism; D017124:Conserved Sequence; D003460:Crystallization; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D049911:Pinctada / Q000254:growth & development / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid
chemical_list: D016326:Extracellular Matrix Proteins; D002686:Chitin; D002119:Calcium Carbonate