HBV X protein interacts with cytoskeletal signaling proteins through SH3 binding.

The aim of this study was to investigate interactions between cellular SH3-containing proteins and the proline-rich domain in Hepatitis B Virus (HBV) X protein (HBx) The proline-rich domain of HBx (amino acids 19-58) as well as the relevant site-directed mutagenesis (proline to alanine residues) were cloned into pGEX-5X-1 and expressed as GST-PXXP and GST-AXXA probes. Panomics SH3 domain arrays were probed using both GST-PXXP and GST-AXXA to identify potential interacting SH3 domain containing proteins. The specific interactions were confirmed by the immunoprecipitation of the full-length SH3 domain-containing protein. We report here the binding assay which demonstrated interaction between PXXP domain in HBx and the SH3-domain containing proteins, in particular various signaling proteins involved in cytoskeletal reorganization. Our findings were consistent with similar virus-host interactions via SH3 binding for other viruses such as hepatitis C virus (HCV) and human immunodeficiency virus (HIV) Further characterization of the proline-rich binding to SH3 domains could yield important information for the design of novel therapeutic measures against downstream disease causative effects of HBx in the liver cells.