Sánchez-Beato A R, López R, García J L
Department of Molecular Microbiology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.
FEMS Microbiol Lett. 1998 Jul 1;164(1):207-14. doi: 10.1111/j.1574-6968.1998.tb13087.x.
The gene pcpA that encodes a novel pneumococcal choline-binding protein has been cloned and characterized. Northern blot analysis revealed that pcpA is expressed during the exponential phase of growth of pneumococci as a monocistronic transcript of about 2.3 kb. The transcription start site has been located 132 bp upstream of the start codon and the proposed -35 and -10 boxes that are highly similar to those of the typical sigma 70 promoters from Escherichia coli. This gene encodes a putative 79 kDa protein that contains a typical C-terminal choline-binding domain (ChBD). The ChBD of PcpA is built up by 11 identical motifs of 20 amino acids plus a tail of 19 amino acids, which represents the longest ChBD that has been characterized so far. Interestingly, two tandem arrays of five characteristic amphipathic leucine reach repeats (LRRs) of 22-26 amino acids in length have been found in the N-terminal region of PcpA. Since LRRs have been proposed to be involved in protein-protein and protein-lipid interactions our findings suggests a role for PcpA in pneumococcal adhesion.
编码一种新型肺炎球菌胆碱结合蛋白的基因pcpA已被克隆并进行了表征。Northern印迹分析表明，pcpA在肺炎球菌生长的指数期作为约2.3 kb的单顺反子转录本表达。转录起始位点位于起始密码子上游132 bp处，其推测的-35和-10框与来自大肠杆菌的典型σ70启动子的框高度相似。该基因编码一种推定的79 kDa蛋白，其包含典型的C末端胆碱结合结构域（ChBD）。PcpA的ChBD由11个相同的20个氨基酸基序加上19个氨基酸的尾部组成，这是迄今为止已表征的最长的ChBD。有趣的是，在PcpA的N末端区域发现了两个由五个长度为22-26个氨基酸的特征性两亲性亮氨酸重复序列（LRR）组成的串联阵列。由于LRR被认为参与蛋白质-蛋白质和蛋白质-脂质相互作用，我们的发现表明PcpA在肺炎球菌黏附中起作用。
