The structure-function relationship analysis of Prismalin-14 from the prismatic layer of the Japanese pearl oyster, Pinctada fucata.
The mollusk shell is a hard tissue consisting of calcium carbonate and organic matrices. The organic matrices are considered to play important roles in shell formation. We have previously identified a prismatic layer-specific protein named Prismalin-14, which consists of 105 amino acid residues and includes four structurally characteristic regions; a repeated sequence of Pro-Ile-Tyr-Arg, a Gly/Tyr-rich region and N- and C-terminal Asp-rich regions. Prismalin-14 showed an inhibitory activity on calcium carbonate precipitation and a calcium-binding ability in vitro. In this study, we prepared some molecular species of recombinant proteins including Prismalin-14 and its truncated proteins in an Escherichia coli expression system to reveal a structure-function relationship of Prismalin-14. The results showed that the Gly/Tyr-rich region was responsible for chitin binding and was identified as a novel chitin-binding sequence. On the other hand, both N- and C-terminal Asp-rich regions are related to inhibitory activity on calcium carbonate precipitation in vitro. Immunohistological observation revealed that Prismalin-14 was localized at the acid-insoluble organic framework including chitin. All these results strongly suggest that Prismalin-14 is a framework protein that mediates chitin and calcium carbonate crystals by using its acidic and chitin-binding regions.
Suzuki
Michio
M
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan.
Nagasawa
Hiromichi
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002119:Calcium Carbonate / Q000737:chemistry; D011232:Chemical Precipitation; D002686:Chitin / Q000378:metabolism; D017931:DNA Primers; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010125:Ostreidae; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship