Virus Structure and Assembly
You have reached the Prevelige laboratory in the Department
of Microbiology at the University
of Alabama at Birmingham. The lab studies virus assembly using
a wide variety of techniques. We are interested in the manner in
which viral subunits specifically recognize one another and associate
to from a closed viral capsid (as pictured above). One of the central
questions is how otherwise identical protein subunits can alter their
conformation to form hexavalent and pentavalent clusters (as pictured
above) during the process of assembly. This phenomenon requires conformational
plasticity in the subunit as well as control mechanisms to insure
the proper positioning of the switched subunits on the growing capsid
surface. Our general approach is to apply biophysical techniques
to in vitro studies. Understanding the process of virus assembly
is key to designing antivirals targeted at inhibition of assembly.
Experimental Systems and Approaches
The lab studies the assembly of
two different viruses, the Salmonella typhimurium bacteriophage
P22 and HIV. The P22 system affords the advantages of
being a well defined system in which genetic manipulations
are straightforward. Milligram quantities of structural
proteins can be purified and studied in our in vitro assembly
system. HIV is a technically more challenging system
which affords the advantages of immediate medical relevance
and providing a window in virus/host interactions. More
detailed information on the research underway in the laboratory may
be found by selecting the Research link. Individual projects are
also described in the Members section.
The Structure and Assembly of dsDNA Bacteriophage
Bacteriophage assembly proceeds through the initial formation of a procapsid into which the DNA is packaged. The DNA is packaged through a portal located at one vertex. The “portal” protein forms a ring at the vertex and serves as one component of the ATP driven packaging motor. This talk illustrates the “finger trap” mechanism of portal function, and the structure of the nucleation complex responsible for portal incorporation.
Mass Spectrometry of Macromolecular
Mass spectrometry has become a
powerful technique in structural biology as witnessed by the 2002
Nobel prize in Chemistry. Hydrogen/deuterium
exchange can provide
information about the dynamics of macromolecular complexes as well
as identifying subunit/subunit interfaces. This is particularly valuable
when the sample of interest is poorly behaved (insoluble or polymorphous)
or precious.We are using hydrogen/deuterium exchange to identify
changes in intersubunit interfaces during viral morphogeneis, as
well as to probe the dynamics of viral processes such as DNA packaging.
In a parallel effort we are using chemical crosslinking and mass
spec. analysis to obtain distance constraints which will then be
used to position subunits of known three-dimensional structure in
three dimensional space.
Virus Based Nanotechnology
Viral capsids represent symmetrical nanoscale platforms that are amenable to both genetic and chemical manipulation. In collaboration with labs at the University of Alabama and Montana State University we are using bacteriophage P22 as a platform for photo-catalysis and nano-medicine. We have developed a variety of approaches to take advantage of the inherent symmetry of the capsid to pattern either semiconductor materials (photo-catalysis) or targeting peptides (nano-medicine) on the surface of the capsid. We have also developed a variety of approaches to load cargo such as TiO2, proteins, or nucleic acids into the interior of the particles.