Phosphorylation of the hepatitis B virus core protein by glyceraldehyde-3-phosphate dehydrogenase protein kinase activity.

Abstract

In order to characterize the hepatitis B virus (HBV) hepatocellular receptor, several proteins have previously been identified in HepG2 hepatoma cells and in primary cultured normal human hepatocytes (PCHs) that reacted with an anti-idiotypic antibody against a preS1(21-47)-specific MAb (F35.25). Here, we report the identification of one of these preS1-binding proteins, a 35 kDa protein (preS1-BP35), as glyceraldehyde-3-phosphate dehydrogenase (GAPD). GAPD is well-known as a key enzyme involved in glycolysis and gluconeogenesis. Nevertheless, GAPD has also been shown to have many other functions such as protein kinase activity (GAPD-PK). HBV core particles derived from infected hepatocytes possess an associated kinase activity that phosphorylates HBcAg, and the nucleocapsid

Cyclin-Dependent Kinase 2 Phosphorylates S/T-P Sites in the Hepadnavirus Core Protein C-Terminal Domain and Is Incorporated into Viral Capsids

“…We observed phosphorylation of HBV capsids purified from HepG2 cells in an in vitro kinase reaction with no exogenous kinase added ( Fig. 1), indicating the presence of a kinase associated with the purified capsids, as reported by others using HBV capsids from infected human liver and hepatoma cells (1,12,18,25). Furthermore, the endogenous kinase activity was associated with the capsids independent of the viral polymerase or pgRNA, since HepG2 capsids made in the absence of polymerase (Pol Ϫ ) and consequently unable to package pgRNA were also phosphorylated (Fig.…”

“…PKC has been reported to be incorporated into HBV capsids (23,25,48,64). However, other reports have argued that neither PKC, PKA, nor casein kinase II (CKII) is the endogenous kinase (12,25,26). The aforementioned 46-kDa serine kinase was also proposed to be packaged in HBV capsids (26), but Ϫ (39,43).…”

“…Several kinases have been reported to phosphorylate the core protein in vitro, including protein kinase C (PKC) (23)(24)(25)(26)64), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (12), a 46-kDa serine kinase (26), and serine-arginine protein kinases 1 and 2 (SRPK1 and -2) (10). In all these cases, the site(s) of core phosphorylation was never defined, except that SRPK1 and -2 were shown to phosphorylate the HBc CTD in vitro (10,45) and in Escherichia coli (8).…”

Central Role of a Serine Phosphorylation Site within Duck Hepatitis B Virus Core Protein for Capsid Trafficking and Genome Release

“…The suggested model is in line with the previous observation in the duck model that serum-derived nucleocapsids are non-phosphorylated whereas nucleocapsids from liver tissue are highly phosphorylated (14). It is tempting to speculate that incoming and recycling capsids are phosphorylated by a capsid-associated kinase activity of cellular origin, which has been described in the WHV and HBV system (27)(28)(29)(30)(31)(32)(33).…”

Impact of solar Ultraviolet-B on the proteome in soybean lines differing in flavonoid contents

“…Most of the spots, identified as Rubisco activase (spots 44-46), Rubisco small subunit (spots 42 and 43), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (spots 48-51), phosphoglycerate kinase (spots 40 and 52), phosphoribulokinase (spots 41 and 47) or other enzymes (spots 53-55), were decreased by UV-B radiation (Tables 1 and 3). In addition to catalyzing reactions in the Calvin cycle, GAPDH is also reported to have protein kinase activity (Duclos-Vallee et al, 1998), to bind RNA (Nagy and Rigby, 1995), and to increase ribozyme (Sioud and Jespersen, 1996) and phosphotransferase activities (Engel et al, 1998). Other environmental stresses have been reported to increase GAPDH level (Yang et al, 1993;Chang et al, 2000;Russell et al, 1990), however, four spots of GAPDH were decreased by UV-B in the present study.…”