Arch Virol (2006) 151: 155–165
Preliminary x-ray characterization of authentic
providence virus and attempts to express its coat
protein gene in recombinant baculovirus
D. J. Taylor
, J. A. Speir
, V. Reddy
, G. Cingolani
, F. M. Pringle
L. A. Ball
, and J. E. Johnson
Department of Chemistry and Biochemistry, University of California,
San Diego, La Jolla, CA, U.S.A.
Department of Molecular Biology, The Scripps Research Institute,
La Jolla, CA, U.S.A.
Department of Microbiology, University of Alabama at Birmingham,
Birmingham, AL, U.S.A.
Received December 16, 2004; accepted April 1, 2005
Published online October 7, 2005
Summary. Providence Virus (PrV) is a non-envoloped, T = 4 icosahedral beta-
tetravirus that undergoes autocatalytic cleavage of its coat protein precursor after
capsid assembly. This is also a well characterized function of Nudaurelia
capensis ω virus (NωV), a member of the related omegatetraviruses, whose x-ray
structure has been determined. Virus-like particle (VLP) production of PrV in
a recombinant baculovirus expression system was attempted to obtain high VLP
yields for comparison of structural and autocatalytic active site properties between
these virus groups. This resulted in insoluble aggregates of PrV coat protein
even though NωV VLPs have been successfully produced in the same system.
Betatetraviruses may be more dependent on compartmentalization and availability
of their full-length genome for proper folding and assembly. However, crystals
were grown of limited quantities of authentic PrV produced in cell culture and
a partial X-ray data set collected to 3.8A
resolution. The virus particle position
and orientation in the unit cell was determined by space group consideration and
rotation function analysis. A phasing model, based on NωV, was developed to
initiate the structure solution of PrV.
ProvidenceVirus (PrV) is a member of the Tetraviridae, a family of nonenveloped,
T = 4, icosahedral viruses that exclusively infect insects of the Lepidopteran order.
Viruses in this family have single-stranded, positive-sense RNA genomes and