Navarre W W, Schneewind O
Department of Microbiology and Immunology, University of California, Los Angeles, School of Medicine 90024.
Mol Microbiol. 1994 Oct;14(1):115-21. doi: 10.1111/j.1365-2958.1994.tb01271.x.
Many surface proteins are thought to be anchored to the cell wall of Gram-positive bacteria via their C-terminus. Cell wall anchoring requires a specific sorting signal, normally located at the predicted C-terminus of surface proteins. Here we show that when placed into the middle of a polypeptide chain, the sorting signal causes the specific cleavage of the precursor as well as the cell wall anchoring of its N-terminal fragment, while the C-terminal fragment remains within the cytoplasm. N-terminal sequencing of the C-terminal cleavage fragment suggests that the cleavage site is located between threonine (T) and glycine (G) of the LPXTG motif, the signature sequence of cell wall sorting signals. All surface proteins harbouring an LPXTG sequence motif may therefore be cleaved and anchored by a universal mechanism. We also propose a novel hypothesis for the cell wall linkage of surface proteins in Gram-positive bacteria.
许多表面蛋白被认为是通过其C末端锚定在革兰氏阳性菌的细胞壁上。细胞壁锚定需要一个特定的分选信号，通常位于表面蛋白预测的C末端。在这里我们表明，当分选信号置于多肽链中间时，它会导致前体的特异性切割及其N末端片段的细胞壁锚定，而C末端片段则保留在细胞质中。对C末端切割片段的N末端测序表明，切割位点位于细胞壁分选信号的特征序列LPXTG基序的苏氨酸（T）和甘氨酸（G）之间。因此，所有含有LPXTG序列基序的表面蛋白可能都通过一种通用机制进行切割和锚定。我们还提出了一个关于革兰氏阳性菌表面蛋白细胞壁连接的新假说。
