Mattingly S J, Johnston B P
Department of Microbiology, University of Texas Health Science Center at San Antonio 78284.
Infect Immun. 1987 Oct;55(10):2383-6. doi: 10.1128/iai.55.10.2383-2386.1987.
The cellular locations of deacylated lipoteichoic acid (dLTA) and lipoteichoic acid (LTA) were examined in late-exponential-phase cells of a serotype III strain of Streptococcus agalactiae (group B streptococci [GBS]) isolated from an infant with late-onset meningitis and compared with a fresh clinical isolate of Streptococcus pyogenes (group A streptococci [GAS]). LTA and dLTA were found to be associated with the protoplast membranes of both organisms, with only dLTA found in mutanolysin cell wall digests. Both organisms released dLTA during growth, but only the GAS released substantial levels of LTA into the culture medium. However, penicillin treatment (5 micrograms/ml for 60 min) of GBS resulted in the recovery of LTA in cell wall digests as well as in the culture medium. These results suggest that under normal growth conditions, the hydrophobic region (glycolipid) of LTA remains associated with the cytoplasmic membrane of GBS and unavailable for hydrophobic interactions at the cell surface with epithelial cells. In contrast, release of LTA into the environment by the GAS allows the fatty acid moieties to interact with hydrophobic domains on the surface of epithelial cells. These results may help explain the marked differences in the specificity of binding between these two major streptococcal pathogens for human fetal and adult epithelial cells.
对从一名患有晚发性脑膜炎的婴儿中分离出的B族链球菌（GBS）血清型III菌株的指数生长后期细胞中去酰基脂磷壁酸（dLTA）和脂磷壁酸（LTA）的细胞定位进行了研究，并与化脓性链球菌（A组链球菌[GAS]）的新鲜临床分离株进行了比较。发现LTA和dLTA与这两种生物体的原生质膜相关，在变溶菌素细胞壁消化物中仅发现了dLTA。两种生物体在生长过程中都会释放dLTA，但只有GAS会向培养基中释放大量的LTA。然而，用青霉素（5微克/毫升，处理60分钟）处理GBS会导致在细胞壁消化物以及培养基中回收LTA。这些结果表明，在正常生长条件下，LTA的疏水区域（糖脂）仍与GBS的细胞质膜相关，无法在细胞表面与上皮细胞进行疏水相互作用。相比之下，GAS将LTA释放到环境中，使得脂肪酸部分能够与上皮细胞表面的疏水结构域相互作用。这些结果可能有助于解释这两种主要链球菌病原体对人类胎儿和成人上皮细胞结合特异性的显著差异。
