NUCLEOTIDE-SEQUENCE ANALYSIS OF THE GENE ENCODING THE CAULOBACTER-CRESCENTUS PARACRYSTALLINE SURFACE-LAYER PROTEIN
NUCLEOTIDE-SEQUENCE ANALYSIS OF THE GENE ENCODING THE CAULOBACTER-CRESCENTUS PARACRYSTALLINE SURFACE-LAYER PROTEIN
复制标题
DOI：
10.1139/m92-033
复制
发表时间：
1992-03-01
影响因子：
2.8
通讯作者：
SMIT, J
中科院分区：
文献类型：
--
作者：
GILCHRIST, A;FISHER, JA;SMIT, J
测定了新月茎杆菌CB15A副晶表面(S)层蛋白（rsaA）编码基因rsaA的全核苷酸序列。rsaA基因编码了一个含有1026个氨基酸的蛋白质，预计分子量为98 132。成熟RsaA蛋白的蛋白酶裂解和可检索肽的氨基酸测序得到两个肽：一个与预测氨基酸序列约三分之二的区域对齐，第二个肽对应于预测的羧基端。因此，在输出过程中，RsaA蛋白的羧基部分没有发生裂解处理，除了去除初始蛋氨酸残基外，该蛋白没有经过裂解产生成熟蛋白。预测的RsaA氨基酸谱不寻常，以小的中性残基为主。除天冬氨酸外，带电氨基酸的比例相对较低，导致蛋白质呈酸性，预测pI为3.46。与大多数其他测序的s层蛋白一样，RsaA不含半胱氨酸残基。对Swiss Protein Bank 17的同源性扫描没有产生与预测的RsaA序列密切匹配的结果。然而，RsaA蛋白与其他细菌的一些输出蛋白（包括溶血素）具有可测量的同源性。特别令人感兴趣的是RsaA蛋白的一个特定区域，该区域与几种蛋白酶和溶血素中发现的甘氨酸和天冬氨酸残基的重复区域同源。这些重复序列与钙的结合有关，从而决定了这些蛋白质的结构和生物活性。存在于RsaA蛋白中的那些可能具有类似的功能，因为s层的组装和表面附着需要钙。RsaA蛋白与其他10种s层蛋白具有一定的同源性，其中弯曲杆菌胎儿s层蛋白的同源性最高。
The entire nucleotide sequence of the rsaA gene, encoding the paracrystalline surface (S) layer protein (RsaA) of Caulobacter crescentus CB15A, was determined. The rsaA gene encoded a protein of 1026 amino acids, with a predicted molecular weight of 98 132. Protease cleavage of mature RsaA protein and amino acid sequencing of retrievable peptides yielded two peptides: one aligned with a region approximately two-thirds the way into the predicted amino acid sequence and the second peptide corresponded to the predicted carboxy terminus. Thus, no cleavage processing of the carboxy portion of the RsaA protein occurred during export, and with the exception of the removal of the initial methionine residue, the protein was not processed by cleavage to produce the mature protein. The predicted RsaA amino acid profile was unusual, with small neutral residues predominating. Excepting aspartate, charged amino acids were in relatively low proportion, resulting in an especially acidic protein, with a predicted pI of 3.46. As with most other sequenced S-layer proteins, RsaA contained no cysteine residues. A homology scan of the Swiss Protein Bank 17 produced no close matches to the predicted RsaA sequence. However, RsaA protein shared measurable homology with some exported proteins of other bacteria, including the hemolysins. Of particular interest was a specific region of the RsaA protein that was homologous to the repeat regions of glycine and aspartate residues found in several proteases and hemolysins. These repeats are implicated in the binding of calcium for proper structure and biological activity of these proteins. Those present in the RsaA protein may perform a similar function, since S-layer assembly and surface attachment requires calcium. RsaA protein also shared some homology with 10 other S-layer proteins, with the Campylobacter fetus S-layer protein scoring highest.