Abstract
VPg linkage to the 5′ ends of Picornavirus RNAs requires production of VPg-pUpU. VPg-pUpU is templated by an RNA stem-loop (the ere or oriI) found at different locations in picornavirus genomes. At least one adaptive mutation is required for human rhinovirus type 14 (HRV-14) to use poliovirus type 3 (PV-3) or PV-1 oriI efficiently. One mutation changes Leu-94 of 3C to Pro; the other changes Asp-406 of 3Dpol to Asn. By using an in vitro VPg uridylylation system for HRV-14 that recapitulates biological phenotypes, we show that the 3C adaptive mutation functions at the level of 3C(D) and the 3D adaptive mutation functions at the level of 3Dpol. Pro-94 3C(D) has an expanded specificity and enhanced stability relative to wild-type 3C(D) that leads to production of more processive uridylylation complexes. PV-1/HRV-14 oriI chimeras reveal sequence specificity in 3C(D) recognition of oriI that resides in the upper stem. Asn-406 3Dpol is as active as wild-type 3Dpol in RNA-primed reactions but exhibits greater VPg uridylylation activity due to more efficient recruitment to and retention in the VPg uridylylation complex. Asn-406 3Dpol from PV-1 exhibits identical behavior. These studies suggest a two-step binding mechanism in the assembly of the 3C(D)-oriI complex that leads to unwinding of at least the upper stem of oriI and provide additional support for a direct interaction between the back of the thumb of 3Dpol and 3C that is required for 3Dpol recruitment to and retention in the uridylylation complex.
Original language | English (US) |
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Pages (from-to) | 12485-12495 |
Number of pages | 11 |
Journal | Journal of virology |
Volume | 81 |
Issue number | 22 |
DOIs | |
State | Published - Nov 2007 |
All Science Journal Classification (ASJC) codes
- Microbiology
- Immunology
- Insect Science
- Virology