Koba H, Okuda K, Watanabe H, Tagami J, Senpuku H
Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Tokyo, Japan.
Oral Microbiol Immunol. 2009 Apr;24(2):162-9. doi: 10.1111/j.1399-302X.2008.00490.x.
Streptococcus gordonii interacts with the salivary pellicle on the tooth surface and plays an important role in dental biofilm formation. Reports show that the analog Ssp peptide (A11K; alanine to lysine at position 11 in the arranged sequence, (1)DYQAKLAAYQAEL(13)) of SspA and SspB of S. gordonii increased binding to the salivary agglutinin (gp-340/DMBT1) peptide (scavenger receptor cysteine-rich domain 2: SRCRP2). To determine the role of lysine in the binding of the Ssp(A11K) peptide to SRCRP2, we investigated whether an additional substitution by lysine influenced the binding of Ssp(A11K) peptide to SRCRP2 using a BIAcore biosensor assay.
Six analogs of the Ssp peptide with positive charges in surface positions on the structure were synthesized using substitution at various positions.
The binding activity of analog Ssp(A4K-A11K) peptide was significantly higher than the other Ssp analogs. The binding activity rose under low ionic strength conditions. The distance between positively charged amino acids in the Ssp(A4K-A11K) peptide between 4K and 11K was 1.24 +/- 0.02 nm and was close to the distance (1.19 +/- 0.00 nm) between Q and E, presenting a negative charged area, on SRCRP2 using chemical computing graphic analysis. The molecular angle connecting 1D-11K-4K in the Ssp(A4K-A11K) peptide secondary structure was smaller than the other peptide angles (1D-11K-XK). The Ssp(A4K-A11K) peptide showed higher inhibiting activity for Streptococcus mutans binding to saliva-coated hydroxyapatite than the (A11K) peptide.
The positioning of lysine is important for binding between Ssp peptide and SRCRP2, and the inhibiting effect on S. mutans binding to the tooth surface.
戈登氏链球菌与牙齿表面的唾液薄膜相互作用，在牙菌斑形成中起重要作用。报告显示，戈登氏链球菌SspA和SspB的类似物Ssp肽（A11K；排列序列中第11位的丙氨酸替换为赖氨酸，(1)DYQAKLAAYQAEL(13)）增加了与唾液凝集素（gp - 340/DMBT1）肽（富含半胱氨酸的清道夫受体结构域2：SRCRP2）的结合。为了确定赖氨酸在Ssp(A11K)肽与SRCRP2结合中的作用，我们使用BIAcore生物传感器分析法研究了赖氨酸的额外取代是否会影响Ssp(A11K)肽与SRCRP2的结合。
通过在不同位置进行取代，合成了六种在结构表面位置带有正电荷的Ssp肽类似物。
类似物Ssp(A4K - A11K)肽的结合活性显著高于其他Ssp类似物。在低离子强度条件下结合活性升高。使用化学计算图形分析，Ssp(A4K - A11K)肽中4K和11K之间带正电荷氨基酸的距离为1.24±0.02 nm，接近SRCRP2上Q和E之间的距离（1.19±0.00 nm），呈现出一个带负电荷的区域。Ssp(A4K - A11K)肽二级结构中连接1D - 11K - 4K的分子角度小于其他肽角度（1D - 11K - XK）。Ssp(A4K - A11K)肽对变形链球菌结合唾液包被的羟基磷灰石的抑制活性高于(A11K)肽。
赖氨酸的定位对于Ssp肽与SRCRP2之间的结合以及对变形链球菌结合牙齿表面的抑制作用很重要。
