The pathogenesis of severe acute respiratory syndrome coronavirus (SARS-CoV) is an important issue for treatment and prevention of SARS. Recently, SARS-CoV 3CL(pro) protease has been implied to be possible relevance to SARS-CoV pathogenesis. In this study, we intended to identify potential 3CL(pro)-interacting cellular protein(s) using the phage-displayed human lung cDNA library. The vacuolar-H+ ATPase (V-ATPase) G1 subunit that contained a 3CL(pro) pro cleavage site-like motif was identified as a 3CL(pro)-interacting protein, as confirmed using the co-immunoprecipitation assay and the relative affinity assay. In addition, our result also demonstrated the cleavage of the VATPase G1 fusion protein and the immunoprecipitation of cellular V-ATPase G1 by the 3CL(pro). Moreover, loading cells with SNARF-I pH-sensitive dye showed that the intracellular pH in 3CL(pro)-expressing cells was significantly lower as compared to mock cells. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
