Chevalier C, Saillard C, Bove J M
Laboratoire de Biologie Cellulaire et Moléculaire, Institut National de la Recherche Agronomique et Université de Bordeaux II, Villenave D'Ornon, France.
J Bacteriol. 1990 Oct;172(10):6090-7. doi: 10.1128/jb.172.10.6090-6097.1990.
Spiralin is the major membrane protein of the helical mollicute Spiroplasma citri. A similar protein occurs in the membrane of Spiroplasma melliferum, an organism related to S. citri. The gene encoding spiralin has been sequenced. A restriction fragment of the spiralin gene has been used as a probe to detect the gene encoding S. melliferum spiralin. A 4.6-kilobase-pair ClaI DNA fragment from S. melliferum strongly hybridized with the probe. This fragment was inserted in pBR322 and cloned in Escherichia coli. It was further subcloned in the replicative forms of M13mp18 and M13mp19, and its nucleotide sequence was determined (GenBank accession number M33991). An open reading frame showing 88.6% base sequence homology with the S. citri spiralin gene could be identified and was assumed to be the gene encoding S. melliferum spiralin. The deduced amino acid sequence of the protein had 75% homology with the spiralin sequence. In particular, the two proteins possess a stretch of 20 amino acids which can form an alpha-helix, in which all polar amino acids occupy approximately one-third of the axial projection down the helix. On the basis of these data and published data, we propose a topological model for the structural organization of the spiralin in the cell membrane of spiroplasmas.
螺旋蛋白是螺旋形软体菌柑橘螺原体的主要膜蛋白。在与柑橘螺原体相关的蜜蜂螺原体的膜中也存在类似的蛋白。编码螺旋蛋白的基因已被测序。螺旋蛋白基因的一个限制性片段已被用作探针来检测编码蜜蜂螺原体螺旋蛋白的基因。来自蜜蜂螺原体的一个4.6千碱基对的ClaI DNA片段与该探针强烈杂交。这个片段被插入到pBR322中并在大肠杆菌中克隆。它进一步被亚克隆到M13mp18和M13mp19的复制形式中，并确定了其核苷酸序列（GenBank登录号M33991）。可以鉴定出一个与柑橘螺原体螺旋蛋白基因具有88.6%碱基序列同源性的开放阅读框，并假定它是编码蜜蜂螺原体螺旋蛋白的基因。该蛋白推导的氨基酸序列与螺旋蛋白序列有75%的同源性。特别是，这两种蛋白拥有一段由20个氨基酸组成的序列，该序列可以形成一个α螺旋，其中所有极性氨基酸在沿着螺旋的轴向投影中占据大约三分之一。基于这些数据和已发表的数据，我们提出了一个关于螺旋蛋白在螺原体细胞膜中结构组织的拓扑模型。
