Coronavirus JHM: a Virion-associated Protein Kinase

Abstract

SUMMARYCoronavirus JHM contains six major proteins, one of which, the 60000 rnol. wt. nucleocapsid protein pp60, is phosphorylated. In JHM-infected cells ip 60K, the intracellular precursor to pp60 is also phosphorylated. Associated with purified JHM virions is a protein kinase which will phosphorylate pp60 and a variety of exogenous substrates in vitro. The enzyme has the characteristics of a cyclic nucleotideindependent protein kinase. Both the in vivo reaction and the enzyme activity in vitro transferred the y-phosphate of ATP to serine residues on the nucleocapsid protein.

Sequences of the Nucleocapsid Genes from Two Strains of Avian Infectious Bronchitis Virus

“…The major cluster of serine residues from bases 594 to 677 is mirrored almost exactly in the MHV JHM sequence (although this is not otherwise a region of very high homology between the two sequences), and several smaller clusters of serines also have their counterparts in MHV. This is interesting, since it is known that the nucleocapsid protein of MHV is phosphorylated specifically at serine residues (Stohlman & Lai, 1979;Siddell et al, 1981). The amino acid differences between IBV Beaudette and IBV M41 are not distributed evenly along the sequence but are restricted to certain regions.…”

“…It appears that, in general, only the 5' proximal region of each RNA is translated (Stern & Kennedy, 1980b;Rottier et al, 1981;Siddell, 1983: Stern & Sefton, 1984. In the case of avian infectious bronchitis virus (IBV), and of the murine coronavirus murine hepatitis virus (MHV), the smallest mRNA is the most abundant and codes for a phosphorylated (Stohlman & Lai, 1979;Siddell et al, 1981 ;Stohlman et al, 1983) unglycosylated (Sturman, 1977;M acnaughton et al, 1977) polypeptide of 50 000 to 60 000 mol. wt.…”

Coronavirus JHM: Coding Assignments of Subgenomic mRNAs

“…For one-dimensional electrophoresis, cytoplasmic lysates, immunoprecipitates or the products of in vitro translations were mixed with electrophoresis sample buffer (Siddell et al, 1980), boiled for 2 min and electrophoresed on 15 % discontinuous SDS-polyacrylamide gels as described by Laemmli (1970). For two-dimensional electrophoresis, the products of in vitro translations were treated with pancreatic ribonuclease and subjected to non-equilibrium pH gradient electrophoresis (NEPHGE) or isoelectric focussing (IEF) in the first dimension and SDS polyacrylamide gradient gel electrophoresis (PAGE) in the second dimension as described by O'Farrell (1975) and O'Farrell et al (1977) with the modifications described in Siddell et al (1981 a). All gels were stained, dried and exposed for autoradiography or fluorography (Laskey & Mills, 1975).…”

Viral Aspects of Protein Phosphorylation

“…The animal viruses for which phosphoproteins have been reported include members of the following classes: herpesviridae (Pereira et al, 1977;Marsden et al, 1978), adenoviridae (Russell & Blair, 1977;Axelrod, 1978), papovaviridae (Schaffhausen & Benjamin, 1979), hepadnaviridae (Roosink & Siddiqui, 1987), iridoviridae (Aubertin et al, 1980), poxviridae (Sagot & Beaud, 1979), African swine fever virus (Tabar6s et al, 1983), baculoviridae (Kelly & Lescott, 1984), reoviridae (Krystal et al, 1975), parvoviridae (Cotmore & Tattersall, 1986), picornaviridae (La Torre et al, 1980), togaviridae (Waite et al, 1974), coronaviridae (Siddell et al, 1981), rhabdoviridae (Moyer & Summers, 1974), paramyxoviridae (Lamb & Choppin, 1977), orthomyxoviridae (Privalsky & Penhoet, 1977) and retroviridae (Pal et al, 1975;Hizi & Joklik, 1977). There is also a report of a plant virus phosphoprotein (Hahn & Shepherd, 1980).…”