Ganeshkumar N, Hannam P M, Kolenbrander P E, McBride B C
Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Infect Immun. 1991 Mar;59(3):1093-9. doi: 10.1128/iai.59.3.1093-1099.1991.
The nucleotide sequence of a 2.9-kb streptococcal DNA fragment which codes for two proteins with MrS of 36,000 (Streptococcus sanguis adhesin B [SsaB]) and 20,000 has been determined. The ssaB gene is 927 bp and codes for a 34,684-Da protein. The open reading frame coding for the 20-kDa protein is 489 bp and codes for a protein of 17,885 Da. The SsaB protein has a putative hydrophobic 19-amino-acid signal sequence resulting in a 32,620-Mr secreted protein, whereas the 20-kDa protein has no signal sequence. Both proteins are hydrophilic, and neither appears to have a hydrophobic membrane anchor sequence in the carboxy-terminal region. A DNA sequence homology of 73% exists between the cloned fragment containing the ssaB gene from S. sanguis 12 and the cloned fragment containing the type 1 fimbrial gene of S. sanguis FW213 (J.C. Fenno, D.J. LeBlanc, and P. Fives-Taylor, Infect. Immun. 57:3527-3533, 1989). Amino acid comparisons of the SsaB and type 1 fimbrial proteins show 87% homology, indicating a close similarity of the two proteins. Antiserum raised against the cloned SsaB protein cross-reacts with a 38-kDa protein identified from Streptococcus gordonii (S. sanguis) PK488 which was proposed to mediate coaggregation with Actinomyces naeslundii PK606 (P.E. Kolenbrander and R.N. Andersen, Infect. Immun. 58:3064-3072, 1990). The SsaB adhesion may play a role in oral colonization by binding either to a receptor on saliva or to a receptor on actinomyces.
已确定一段2.9kb链球菌DNA片段的核苷酸序列，该片段编码两种蛋白质，其相对分子质量分别为36000（血链球菌粘附素B [SsaB]）和20000。ssaB基因长927bp，编码一种34684Da的蛋白质。编码20kDa蛋白质的开放阅读框为489bp，编码一种17885Da的蛋白质。SsaB蛋白有一个推测的由19个氨基酸组成的疏水信号序列，产生一个相对分子质量为32620的分泌蛋白，而20kDa蛋白没有信号序列。两种蛋白质都是亲水性的，在羧基末端区域似乎都没有疏水的膜锚定序列。来自血链球菌12的含有ssaB基因的克隆片段与含有血链球菌FW213 1型菌毛基因的克隆片段之间存在73%的DNA序列同源性（J.C. 芬诺、D.J. 勒布朗克和P. 菲夫斯-泰勒，《感染与免疫》57:3527 - 3533，1989年）。SsaB和1型菌毛蛋白的氨基酸比较显示同源性为87%，表明这两种蛋白质非常相似。针对克隆的SsaB蛋白产生的抗血清与从戈登链球菌（血链球菌）PK488中鉴定出的一种38kDa蛋白发生交叉反应，该蛋白被认为介导与内氏放线菌PK606的共聚（P.E. 科伦布兰德和R.N. 安德森，《感染与免疫》58:3064 - 3072，1990年）。SsaB粘附素可能通过与唾液上的受体或放线菌上的受体结合，在口腔定植中发挥作用。
