Novel barnacle underwater adhesive protein is a charged amino acid-rich protein constituted by a Cys-rich repetitive sequence
Novel barnacle underwater adhesive protein is a charged amino acid-rich protein constituted by a Cys-rich repetitive sequence
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DOI：
10.1042/0264-6021:3560503
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发表时间：
2001-06-01
影响因子：
4.1
通讯作者：
Kamino, K
中科院分区：
文献类型：
--
作者：
Kamino, K
藤壶水泥是一种用于永久沉降的水下粘合剂，是一种不溶性蛋白质复合物。研究人员已经开发出了一种使巨藻胶凝物可溶的方法，并且在先前的研究中已经确定了三种主要的蛋白质。为了在较低的分子质量范围内对M. I . osa水泥蛋白进行研究，采用反相高效液相色谱法对水泥蛋白进行分离，发现了一个先前未识别的蛋白，命名为20 kDa M. I . osa水泥蛋白（Mrcp-20k）。克隆Mrcp-20k cDNA，揭示其初级结构。该cDNA全长902 bp，编码202个氨基酸长的开放阅读框，其中包含信号序列的19个氨基酸。计算得到二硫化物形式的分子质量为20 357 Da，成熟多肽的等电点为4.72。Mrcp-20k具有丰富的胱氨酸残基和带电氨基酸。最常见的氨基酸是Cys(17.5%)，其次是Asp（11.5%）、Glu（10.4%）和His（10.4%）。对Cys残基的比对表明，该蛋白的初级结构由6个退化重复组成，每个重复约30个残基长。Mrcp-20k在不溶性水泥配合物中没有分子间二硫键和Cys的自由巯基。丰富的Cys被认为通过分子内二硫化物键的形成在维持分子表面带电氨基酸的拓扑结构中起作用。讨论了丰富的带电氨基酸可能的功能，包括与基质上各种表面金属的相互作用。
Barnacle cement is an underwater adhesive that is used for permanent settlement, and is an insoluble protein complex. A method for rendering soluble the cement of Megabalanus I osa has been developed, and three major proteins have been identified in a previous study. To survey the M. I osa cement proteins in a lower molecular mass range, the cement proteins were separated by reversed-phase HPLC and a previously unidentified protein named 20 kDa M. I osa cement protein (Mrcp-20k) was found. Mrcp-20k cDNA was cloned to reveal its primary structure. This cDNA was 902 bp long and encoded a 202 amino acid-long open reading frame, including 19 amino acids of the signal sequence. The molecular mass in the disulphide form was calculated to be 20 357 Da and the isoelectric point of the mature polypeptide was 4.72. Mrcp-20k was characterized by an abundance of Cys residues and charged amino acids. The most common amino acid was Cys (17.5 %), with Asp (11.5 %), Glu (10.4 %) and His (10.4 %) following in order of magnitude. The alignment of the Cys residues indicated the primary structure of this protein to consist of six degenerated repeats, each about 30 residues long. Mrcp-20k has no intermolecular disulphide bonds and no free thiol groups of Cys in the insoluble cement complex. Abundant Cys is thought to play a role in maintaining the topology of charged amino acids on the molecular surface by intramolecular disulphide-bond formation. The possible function of abundant charged amino acids, including the interaction with a variety of surface metals on the substratum, is discussed.