Sára M, Kalsner I, Sleytr U B
Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Wien, Austria.
Arch Microbiol. 1988;149(6):527-33. doi: 10.1007/BF00446756.
Labelling experiments using a positively charged topographical marker for electron microscopy, polycationized ferritin, showed that the S-layers of two closely related clostridia Clostridium thermohydrosulfuricum L111-69 and C. thermosaccharolyticum D120-70 do not exhibit a net negative charge, as usually observed for bacterial cell surfaces. Chemical modification of reactive sites confirmed that amino and carboxyl groups are exposed on the S-layer surface of both strains. Amino-specific, bifunctional agents crosslinked both S-layer lattices. Studies with carbodiimides revealed that only the S-layer surface of C. thermohydrosulfuricum L111-69 had amino and carboxyl groups closely enough aligned to permit electrostatic interactions between the constituent protomers. The regular structure of this S-layer lattice was lost upon converting the carboxyl groups into neutral groups by amidation. Disintegration of both S-layer lattices occurred upon N-acetylation or N-succinylation of the free amino groups. Adhesion experiments showed that in neutral and weakly alkaline environment whole cells of C. thermosaccharolyticum D120-70 exhibited a stronger tendency to bind to charged surfaces than whole cells of C. thermohydrosulfuricum L111-69, but showed a lower tendency to bind to hydrophobic materials.
使用带正电荷的电子显微镜拓扑标记物聚阳离子化铁蛋白进行的标记实验表明，两种密切相关的梭菌——热硫化氢梭菌L111 - 69和热解糖梭菌D120 - 70的S层并未表现出净负电荷，而细菌细胞表面通常会观察到这种电荷。对反应位点的化学修饰证实，两种菌株的S层表面都暴露有氨基和羧基。氨基特异性双功能试剂使两种S层晶格交联。用碳二亚胺进行的研究表明，只有热硫化氢梭菌L111 - 69的S层表面的氨基和羧基排列得足够紧密，能够使组成原体之间发生静电相互作用。通过酰胺化将羧基转化为中性基团后，这种S层晶格的规则结构丧失。游离氨基进行N - 乙酰化或N - 琥珀酰化后，两种S层晶格均发生解体。粘附实验表明，在中性和弱碱性环境中，热解糖梭菌D120 - 70的全细胞比热硫化氢梭菌L111 - 69的全细胞表现出更强的与带电表面结合的倾向，但与疏水材料结合的倾向较低。
