From: ncbi-seminar-admin@ncbi.nlm.nih.gov on behalf of Yanli Wang
[ywang@keystone.nlm.nih.gov]
Sent: Monday, May 20, 2002 10:21 AM
To: ncbi-seminar@keystone.nlm.nih.gov
Subject: seminar (fwd)


Seminar will be given at 11:00am today at the 5th floor conference room 
in building 38A. Sorry for the short notice.


Yanli


On May 17,  3:28pm, Yanli Wang wrote:
> Subject: visitor
> Hi, everyone,
> 
> Dr. Chunxu Qu will visit NCBI next Monday and Tuseday. She will give a
> seminar at 11:00am in the 5th floor conference room. Title and abstract 
> is in the following. 
> 
> =============================================================
> "The Structure and Function of Cowpea Chlorotic Mottle Virus"
> 
> Cowpea Chlorotic Mottle Virus (CCMV) is a plant virus.
> Its tripartite genome is composed of three unique,
> positive sense, single strand RNA molecules. CCMV is
> stable at pH 5 and swells when the pH is raised to 7.5
> in the absence of divalent cations.  The viral capsid dynamics of the 
> wild type CCMV and the salt stable mutant, K42R, are studied in both 
> compact and swollen conditions using matrix-assisted laser
> desorption/ionization mass spectrometry combined with
> time resolved, limited proteolysis.  In the wild type
> CCMV, the N-termini, which are observed to be inside
> of the virus capsid using X-ray crystallography, are
> transiently exposed to the virus surface in the
> compact form, while they are unexpectedly less mobile
> in the swollen condition.  The interactions between
> protein and RNA are weaker in the swollen condition,
> and the N-termini are probably rearranged in the
> interior of the virus, interacting with the capsid
> protein shell instead of viral RNA.  From the crystal
> structure of the salt stable mutant, it is postulated
> that the R42 residues form salt-bridges with the E34
> residues of the neighbour subunits at the quasi
> sixfolds at basic pH.  These 120 extra salt-bridges
> stabilize the capsid structure of the mutant, but also
> limit the dynamics of the capsid, which makes the
> N-termini less susceptible to trypsin.  These
> observations indicate that the mobility of the
> N-termini is coupled with the dynamics of the capsid.
> However, these salt bridges do not eliminate the
> swelling ability of the virus. These results support
> the co-translational disassembly pathway of the
> viruses with swelling ability. In the end, some 
> informatics work will be talked brieftly along with an 
> introduction about the computational platform at 
> GeneFormatics.
> ============================================================
> 
> Yanli
>-- End of excerpt from Yanli Wang