Molecular evolution and functionally important structures of molluscan Dermatopontin: implications for the origins of molluscan shell matrix proteins.
A major shell matrix protein originally obtained from a freshwater snail is a molluscan homologue of Dermatopontins, a group of Metazoan proteins also called TRAMP (tyrosine-rich acidic matrix protein). We sequenced and identified 14 molluscan homologues of Dermatopontin from eight snail species belonging to the order Basommatophora and Stylommatophora. The bassommatophoran Dermatopontins fell into three types, one is suggested to be a shell matrix protein and the others are proteins having more general functions based on gene expression analyses. N-glycosylation is inferred to be important for the function involved in shell calcification, because potential N-glycosylation sites were found exclusively in the Dermatopontins considered as shell matrix proteins. The stylommatophoran Dermatopontins fell into two types, also suggested to comprise a shell matrix protein and a protein having a more general function. Phylogenetic analyses using maximum likelihood and Bayesian methods revealed that gene duplication events occurred independently in both basommatophoran and stylommatophoran lineages. These results suggest that the dermatopontin genes were co-opted for molluscan calcification at least twice independently after the divergence of basommatophoran and stylommatophoran lineages, or more recently than we have expected.
Department of Earth Evolution Sciences, Graduate School of Life and Environmental Science, University of Tsukuba, Japan.
Isao
I
Sarashina
Haruyo
H
Yamaguchi
Takuma
T
Haga
Minoru
M
Iijima
Satoshi
S
Chiba
Kazuyoshi
K
Endo
D000595:Amino Acid Sequence; D000818:Animals; D011508:Chondroitin Sulfate Proteoglycans / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D008974:Mollusca / Q000033:anatomy & histology / Q000737:chemistry* / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D014158:Transcription, Genetic / Q000235:genetics
D011508:Chondroitin Sulfate Proteoglycans; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins