Ganeshkumar N, Arora N, Kolenbrander P E
Laboratory of Microbial Ecology, National Institute of Dental Research, Bethesda, Maryland 20892.
J Bacteriol. 1993 Jan;175(2):572-4. doi: 10.1128/jb.175.2.572-574.1993.
Two lipoprotein consensus sequences (Leu-X-X-Cys) are found in the presumptive signal peptide region (positions 12 to 15 and 17 to 20) of saliva-binding protein (SsaB) from Streptococcus sanguis 12. Three analogs of SsaB containing Cys-->Gly mutations were constructed by site-directed mutagenesis of pSA2, the recombinant plasmid expressing SsaB. [3H]palmitate was incorporated into SsaB only when the native Cys-20 residue was present. These data show that SsaB is a lipoprotein and that Cys-20 is the critical site for acylation.
在血链球菌12型唾液结合蛋白（SsaB）的推定信号肽区域（第12至15位和第17至20位）发现了两个脂蛋白共有序列（Leu-X-X-Cys）。通过对表达SsaB的重组质粒pSA2进行定点诱变，构建了三个含有Cys→Gly突变的SsaB类似物。仅当天然的Cys-20残基存在时，[3H]棕榈酸才会掺入SsaB中。这些数据表明SsaB是一种脂蛋白，且Cys-20是酰化的关键位点。
