Ries W, Hotzy C, Schocher I, Sleytr U B, Sára M
Zentrum für Ultrastrukturforschung und Ludwig Boltzmann-Institut für Molekulare Nanotechnologie, Universität für Bodenkultur, Vienna, Austria.
J Bacteriol. 1997 Jun;179(12):3892-8. doi: 10.1128/jb.179.12.3892-3898.1997.
The S-layer of Bacillus stearothermophilus PV72/p2 shows oblique lattice symmetry and is composed of identical protein subunits with a molecular weight of 97,000. The isolated S-layer subunits could bind and recrystallize into the oblique lattice on native peptidoglycan-containing sacculi which consist of peptidoglycan of the A1gamma chemotype and a secondary cell wall polymer with an estimated molecular weight of 24,000. The secondary cell wall polymer could be completely extracted from peptidoglycan-containing sacculi with 48% HF, indicating the presence of phosphodiester linkages between the polymer chains and the peptidoglycan backbone. The cell wall polymer was composed mainly of GlcNAc and ManNAc in a molar ratio of 4:1, constituted about 20% of the peptidoglycan-containing sacculus dry weight, and was also detected in the fraction of the S-layer self-assembly products. Extraction experiments and recrystallization of the whole S-layer protein and proteolytic cleavage fragments confirmed that the secondary cell wall polymer is responsible for anchoring the S-layer subunits by the N-terminal part to the peptidoglycan-containing sacculi. In addition to this binding function, the cell wall polymer was found to influence the in vitro self-assembly of the guanidinium hydrochloride-extracted S-layer protein. Chemical modification studies further showed that the secondary cell wall polymer does not contribute significant free amino or carboxylate groups to the peptidoglycan-containing sacculi.
嗜热脂肪芽孢杆菌PV72/p2的S层呈现倾斜晶格对称性，由分子量为97,000的相同蛋白质亚基组成。分离出的S层亚基可以结合并在含有天然肽聚糖的球状体上重结晶为倾斜晶格，这些球状体由A1γ化学型的肽聚糖和一种估计分子量为24,000的次生细胞壁聚合物组成。次生细胞壁聚合物可以用48%的氢氟酸从含肽聚糖的球状体中完全提取出来，这表明聚合物链与肽聚糖主链之间存在磷酸二酯键。细胞壁聚合物主要由摩尔比为4:1的N-乙酰葡糖胺和N-乙酰甘露糖胺组成，约占含肽聚糖球状体干重的20%，在S层自组装产物的组分中也能检测到。对整个S层蛋白及其蛋白水解切割片段的提取实验和重结晶证实，次生细胞壁聚合物通过N端部分将S层亚基锚定在含肽聚糖的球状体上。除了这种结合功能外，还发现细胞壁聚合物会影响盐酸胍提取的S层蛋白的体外自组装。化学修饰研究进一步表明，次生细胞壁聚合物对含肽聚糖的球状体没有显著的游离氨基或羧基贡献。
