Identification, Characterization, and Expression Levels of Putative Adhesive Proteins From the Tube-Dwelling Polychaete Sabellaria alveolata
Identification, Characterization, and Expression Levels of Putative Adhesive Proteins From the Tube-Dwelling Polychaete Sabellaria alveolata
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DOI：
10.1086/bblv223n2p217
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发表时间：
2012-10-01
影响因子：
1.6
通讯作者：
Flammang, Patrick
中科院分区：
文献类型：
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作者：
Becker, Pierre T.;Lambert, Aurelie;Flammang, Patrick
管栖多毛类动物Sabellaria alveolata的庇护所由矿物颗粒和蛋白质粘固剂组成。组成水泥的粘附蛋白质的基础上，确定其序列相似性与蛋白质的一个adhesionally相关的物种，Phragmatopoma californica。两种带正电荷的蛋白质Sa-1和Sa-2具有共同的特征：它们都具有22 kDa的质量;富含甘氨酸，酪氨酸和碱性残基;并显示重复的肽基序。Sa-1的共有重复序列是KGAY-GAKGLGYGNKAGYGAYG（出现6-8次），而Sa-2显示共有七肽VHKAAWG（5次）和十一肽VHKAAGYGGYG（8次）。还鉴定了富含丝氨酸的蛋白质的两种变体，Sa-3A（22 kDa）和Sa-3B（21 kDa）。它们的丝氨酸残基占75摩尔%，可能是磷酸化的，这意味着Sa-3是非常酸性和带负电荷的。此外，所有粘附蛋白的酪氨酸残基被推测为多巴修饰。尽管S. alveolata和P. californica的主要特征（包括氨基酸组成、翻译后修饰、重复模式、等电点和质量）为两个物种所共有。这表明这些特征对于它们的功能比蛋白质的一级结构更重要。通过定量实时PCR估计每种蛋白质的mRNA丰度，揭示Sa-1、-2、-3A和-3B的相对表达水平分别为约5、11、1.5和1。这些水平可以指示电荷中和现象或可以反映它们在水泥中的功能（界面与本体）。
The shelter of the tube-dwelling polychaete Sabellaria alveolata is composed of mineral particles assembled with spots of a proteinaceous cement. The adhesive proteins constituting the cement were identified on the basis of their sequence similarity with proteins of a phylogenetically related species, Phragmatopoma californica. Two positively charged proteins, Sa-1 and Sa-2, share common features: they both have a mass of 22 kDa; are rich in glycine, tyrosine and basic residues; and show repeated peptide motifs. The consensus repeat of Sa-1 is KGAY-GAKGLGYGNKAGYGAYG (occurring 6-8 times), while Sa-2 displays the consensus heptapeptide VHKAAWG (5 times) and undecapeptide VHKAAGYGGYG (8 times). Two variants of a serine-rich protein, Sa-3A (22 kDa) and Sa-3B (21 kDa), were also identified. Their serine residues account for 75 mol% and are probably phosphorylated, meaning that Sa-3 is very acidic and negatively charged. Moreover, tyrosine residues of all adhesive proteins are presumably modified into DOPA. Although protein sequences are not well-conserved between S. alveolata and P. californica, their main characteristics (including amino acid composition, post-translational modifications, repeated patterns, isoelectric point, and mass) are shared by both species. This suggests that these features are more important for their function than the primary structure of the proteins. The mRNA abundance for each protein was estimated by quantitative real-time PCR, revealing relative expression levels of about 5, 11, 1.5, and 1 for Sa-1, -2, -3A, and -3B, respectively. These levels could be indicative of charge neutralization phenomena or could reflect their function (interface vs. bulk) in the cement.