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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.


Repeat motifs found in shell matrix proteins identified in this study
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Fig8: Repeat motifs found in shell matrix proteins identified in this study

Mentions: Many of the shell matrix proteins identified in this study have repeat sequences, which are generally represented as a low complexity domain in the SMART prediction (Fig. 2). Repeat sequences exist in many skeletal proteins identified from other phyla and are thought to have important roles in biomineralization processes. The GXN (Glycine-X-Asparagine) repeat that is present in the amino acid sequence of isotig 02671 also exists in Nacrein, the carbonic anhydrase in the molluscan shell (Fig. 8). This repeat sequence has been proposed to function by inhibiting the precipitation of calcium carbonate [34]. Therefore, the GXN repeat in isotig 02671 could also be involved in the control of CaCO3 growth. Besides this repeat sequence, the repeat motifs PPRG, GGX, and GGQNTGX are also present in sequences of the shell matrix proteins (Fig. 8). Although the exact function of these repeat sequences is not clear, the existence of a variety of repeat sequences in skeletal proteins suggests that this sequence structure has fundamental roles in biomineralization.Fig. 8


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)

Repeat motifs found in shell matrix proteins identified in this study
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig8: Repeat motifs found in shell matrix proteins identified in this study
Mentions: Many of the shell matrix proteins identified in this study have repeat sequences, which are generally represented as a low complexity domain in the SMART prediction (Fig. 2). Repeat sequences exist in many skeletal proteins identified from other phyla and are thought to have important roles in biomineralization processes. The GXN (Glycine-X-Asparagine) repeat that is present in the amino acid sequence of isotig 02671 also exists in Nacrein, the carbonic anhydrase in the molluscan shell (Fig. 8). This repeat sequence has been proposed to function by inhibiting the precipitation of calcium carbonate [34]. Therefore, the GXN repeat in isotig 02671 could also be involved in the control of CaCO3 growth. Besides this repeat sequence, the repeat motifs PPRG, GGX, and GGQNTGX are also present in sequences of the shell matrix proteins (Fig. 8). Although the exact function of these repeat sequences is not clear, the existence of a variety of repeat sequences in skeletal proteins suggests that this sequence structure has fundamental roles in biomineralization.Fig. 8

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.