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Proteome analysis of shell matrix proteins in the brachiopod Laqueus rubellus.

Isowa Y, Sarashina I, Oshima K, Kito K, Hattori M, Endo K - Proteome Sci (2015)

Bottom Line: We also identified pectin lyase-like, trypsin inhibitor, and saposin B functional domains in the amino acid sequences of the shell matrix proteins.The repertoire of brachiopod shell matrix proteins also contains two basic amino acid-rich proteins and proteins that have a variety of repeat sequences.Our study suggests an independent origin and unique mechanisms for brachiopod shell formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.

ABSTRACT

Background: The calcitic brachipod shells contain proteins that play pivotal roles in shell formation and are important in understanding the evolution of biomineralization. Here, we performed a large-scale exploration of shell matrix proteins in the brachiopod Laqueus rubellus.

Results: A total of 40 proteins from the shell were identified. Apart from five proteins, i.e., ICP-1, MSP130, a cysteine protease, a superoxide dismutase, and actin, all other proteins identified had no homologues in public databases. Among these unknown proteins, one shell matrix protein was identified with a domain architecture that includes a NAD(P) binding domain, an ABC-type transport system, a transmembrane region, and an aspartic acid rich region, which has not been detected in other biominerals. We also identified pectin lyase-like, trypsin inhibitor, and saposin B functional domains in the amino acid sequences of the shell matrix proteins. The repertoire of brachiopod shell matrix proteins also contains two basic amino acid-rich proteins and proteins that have a variety of repeat sequences.

Conclusions: Our study suggests an independent origin and unique mechanisms for brachiopod shell formation.

No MeSH data available.


Molecular mass and isoelectric points. Red symbols represent shell matrix proteins from brachiopod and gray symbols represent shell matrix proteins from mollusca (Marin et al. 2008)
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Fig7: Molecular mass and isoelectric points. Red symbols represent shell matrix proteins from brachiopod and gray symbols represent shell matrix proteins from mollusca (Marin et al. 2008)

Mentions: Shell matrix proteins of molluscs contain aspartic acid-rich proteins that are postulated to interact with Ca2+ [33]. Isotig 01176 has a repeat sequence comprising aspartic acid, suggesting that this region also binds Ca2+ (Fig. 6). However, the brachiopod shell matrix proteins identified in this study do not have unusually low isoelectric points seen for aspartic acid-rich proteins in the molluscan shell (Fig. 7). Among the shell matrix proteins identified in this study, isotig 01521 and isotig 02158 have a relatively high concentration of basic amino acids (Fig. 6). Although it is possible that unusually acidic shell matrix proteins have not been identified in this study, there may exist a general difference in isoelectric points between mollusc and brachiopod shell matrix proteins.Fig. 6


Proteome analysis of shell matrix proteins in the brachiopod Laqueus rubellus.

Isowa Y, Sarashina I, Oshima K, Kito K, Hattori M, Endo K - Proteome Sci (2015)

Molecular mass and isoelectric points. Red symbols represent shell matrix proteins from brachiopod and gray symbols represent shell matrix proteins from mollusca (Marin et al. 2008)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4536745&req=5

Fig7: Molecular mass and isoelectric points. Red symbols represent shell matrix proteins from brachiopod and gray symbols represent shell matrix proteins from mollusca (Marin et al. 2008)
Mentions: Shell matrix proteins of molluscs contain aspartic acid-rich proteins that are postulated to interact with Ca2+ [33]. Isotig 01176 has a repeat sequence comprising aspartic acid, suggesting that this region also binds Ca2+ (Fig. 6). However, the brachiopod shell matrix proteins identified in this study do not have unusually low isoelectric points seen for aspartic acid-rich proteins in the molluscan shell (Fig. 7). Among the shell matrix proteins identified in this study, isotig 01521 and isotig 02158 have a relatively high concentration of basic amino acids (Fig. 6). Although it is possible that unusually acidic shell matrix proteins have not been identified in this study, there may exist a general difference in isoelectric points between mollusc and brachiopod shell matrix proteins.Fig. 6

Bottom Line: We also identified pectin lyase-like, trypsin inhibitor, and saposin B functional domains in the amino acid sequences of the shell matrix proteins.The repertoire of brachiopod shell matrix proteins also contains two basic amino acid-rich proteins and proteins that have a variety of repeat sequences.Our study suggests an independent origin and unique mechanisms for brachiopod shell formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.

ABSTRACT

Background: The calcitic brachipod shells contain proteins that play pivotal roles in shell formation and are important in understanding the evolution of biomineralization. Here, we performed a large-scale exploration of shell matrix proteins in the brachiopod Laqueus rubellus.

Results: A total of 40 proteins from the shell were identified. Apart from five proteins, i.e., ICP-1, MSP130, a cysteine protease, a superoxide dismutase, and actin, all other proteins identified had no homologues in public databases. Among these unknown proteins, one shell matrix protein was identified with a domain architecture that includes a NAD(P) binding domain, an ABC-type transport system, a transmembrane region, and an aspartic acid rich region, which has not been detected in other biominerals. We also identified pectin lyase-like, trypsin inhibitor, and saposin B functional domains in the amino acid sequences of the shell matrix proteins. The repertoire of brachiopod shell matrix proteins also contains two basic amino acid-rich proteins and proteins that have a variety of repeat sequences.

Conclusions: Our study suggests an independent origin and unique mechanisms for brachiopod shell formation.

No MeSH data available.