Identification of receptor-binding site of the mouse hepatitis virus spike protein

点击翻译按钮获取中文摘要

We have previously shown that the N terminal region composed of 330 amino acids of MHV S protein (S1N330) is important for receptor-binding activity, since the S1N330 protein expressed by recombinant vaccina virus binds to the MHV-receptor protein prepared on the membrane paper by Western blot in a similar manner as whole S protein binds to the receptor protein. The aim of this experimetn is to identify the amino acids that participate in the receptor-binding activity in S1N330. We have found that 7MHV strains can use mmCGM1 as a functional receptor. In the S1N330 of these 7 MHV strains, we found 3 major consercative regions which include more than 10 consective amiano acids identical among these 7 MHV strains. We have introduced the mutations in some of amino asids in these regions and analyzed the receptor-binding activity of such mutant proteins. The mutant S1N330 protein with a mutation at amino acid 62 from the N terminus failed to bind to the receptor protein. The receptor binding og a mutant with mutations at 212,214, and 216 was remarkably reduced. These results imply that amino acids at 62,212,214 and 216 play important role for the receptor-binding activity of the MHV s protein. Furthermore, it is suggested that secondary or tertiary structure of SIN330 is necessary for receptor-binding activity, since the region containing amino acid 62 is located apart from a region including amino acids 212,214 and 216 in primary MHV s protein sturucture.