Proteolytic processing of poliovirus polypeptides: antibodies to polypeptide P3-7c inhibit cleavage at glutamine-glycine pairs.

Abstract

Proteolytic processing of poliovirus polypeptides was examined by the addition of antibodies directed against the viral proteins P3-7c and P2-X to a cell-free translation extract prepared from infected HeLa cells. Antisera to P3-7c specifically inhibited in vitro processing at Gln-Gly pairs. Partial amino acid sequence analysis revealed a second Tyr-Gly pair that is utilized in protein processing. Neither Tyr-Gly cleavage is affected by antibody to P3-7c. Anti-P3-7c antibodies react not only with P3-7c but also with P3-6a and P3-2, two viral polypeptides NH2-coterminal with P3-7c. Preimmune and anti-P2-X antibodies had no effect on the processing of poliovirus proteins in vitro. We conclude that the activity responsible for processing poliovirus polypeptides at Gln-Gly pairs resides in the primary structure of P3-7c (or P3-2 and P3-6a) and not in P2-X.

Membrane-dependent uridylylation of the genome-linked protein VPg of poliovirus.

“…We speculate that the first step in initiation is the uridylylation of a Tyr residue near the COOH terminus of the membrane-bound polypeptide P3-9. This modification may activate the Gln-Gly cleavage site within P3-9, possibly by conformational change, such that VPg is cleaved from P3-9 by the virus-encoded proteinase P3-7c (4,6,32). The newly formed VPg-pU or VPg-pUpU can now function as a primer for the primer-dependent, virus-encoded RNA polymerase P3-4b (23,24,33).…”

Picornavirus IRES elements: RNA structure and host protein interactions

“…The polyprotein of all picornaviruses contain embedded proteinases that catalyze cleavages in cis and in trans in a processing cascade (Hanecak et al, 1982;Parks et al, 1989;Skern et al, 1991;Toyoda et al, 1986). Primary cleavages of the polyprotein are mediated by the 3C proteinase (3C pro ), a serine-proteinase with a cysteine active site (Seipelt et al, 1999).…”

Synthesis of Immunogenic, but Non-infectious, Poliovirus Particles in Insect Cells by a Baculovirus Expression Vector

“…Translation of the viral polyprotein is not initiated at the first, Y-proximal AUG, but begins at a later AUG (nucleotide residues 743 to 745 for the P3/Leon/37 strain of poliovirus type 3). During translation, the viral polyprotein is processed via a variety of intermediates into the various poliovirus proteins through the action of at least two virus-coded proteases (Hanecak et al, 1982;Toyoda et al, 1986). When infectious virus is produced in permissive cells, the structural proteins include the capsid proteins, VP1 to VP4.…”