Spring Conference 2011 - Society for General Microbiology

Please note: Abstracts are published as received from the authors and are not subject to editing.
8
Spring Meeting 11–14 April 2011
Harrogate – www.sgmharrogate2011.org.uk
SESSION AbSTrACTS
↑Contents
HA01 Cont.
enable not only replication of viral rNA but also protect newly-synthesized genomes from recognition by host defence mechanisms. The
mechanisms used to create replication sites by NS4B are poorly understood but could be similar to the processes involved in the formation
of Er tubules. in addition, the HCV core protein, which forms the capsid within virions, is targeted specifically to the membranous surface
of lipid droplets. Disrupting the ability of core to target lipid droplets prevents release of infectious virus. using biophysical methods in
live cells, the similarities and differences between HCV core and NS4B proteins and cellular components that target membranes will be
described. These studies illustrate the importance of host membranes and the membrane-binding properties of viral proteins to productive
HCV infection.
Involvement of the cell nucleus in plant virus systemic infections
M. TAliANSKY, S.H. Kim, E. ryabov, N. Kalinina, J. Shaw, S. MacFarlane, J.W.S. Brown
Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA
The nucleolus and Cajal bodies (CBs) are prominent interacting subnuclear domains involved in crucial aspects of cell function such as rNA
metabolism, the cell cycle and aging. Certain viruses interact with these compartments but the functions of such interactions are largely
uncharacterized. in this work, we show that the ability of the Groundnut rosette virus OrF3 protein to move viral rNA long-distances
through the phloem and mediate systemic infection strictly depends on its interaction with CBs, the nucleolus and the major nucleolar
protein, fibrillarin. The OrF3 protein targets and re-organizes CBs into multiple CB-like structures and then enters the nucleolus by causing
fusion of these structures with the nucleolus. This process is mediated by the interaction between OrF3 protein and fibrillarin leading to
the formation of ring-like complexes. These rings formed by both OrF3 and fibrillarin proteins interact with viral rNA encapsidating it and
re-organizing it into helical structures, and thereby play a key role in the assembly of umbraviral rNP complexes capable of long-distance
movement and systemic infection. These results may have functional implications for other viruses, which will be discussed.
Identification of a kinesin-I light chain binding signature in the human genome
Mark P. Dodding, richard Mitter, Ashley Humphries, MiCHAEl WAY
Cell Motility Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln’s Inn Fields, London WC2A 3PX
(email michael.way@cancer.org.uk)
During vaccinia virus infection, newly assembled virus particles, which fuse with the plasma membrane and remain attached to the outside
of the cell recruit a signalling complex of Grb2, Nck, WiP and N-WASP to stimulate Arp2/3 complex-dependent actin polymerization to
enhance their spread into neighbouring cells. Before vaccinia can induce actin polymerization it has to travel from its peri-nuclear site of
assembly to the plasma membrane. it achieves this by recruiting kinesin-1 and undergoing microtubule-based motility. The viral protein A36
interacts directly to the kinesin-1 light chain (KlC). We now show that this interaction is mediated by a bi-partite tryptophan based motif,
which is also found in a number of cellular kinesin-1 binding proteins. Bioinformatic analysis reveals that a related bipartite motif is present
in over 450 human proteins. using vaccinia as a surrogate cargo we show that the bi-partite motifs from a variety of cellular proteins can
recruit KlC to promote virus transport in the absence of A36. Furthermore, these proteins can interact with the KlC outside the context
of infection. Our observations suggest KlC binding depends on a common set of features found in a wide range of proteins with multiple
cellular functions and disease associations.
retrovirus cell-to-cell transmission
Walther Mothes
Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Ave, New Haven, CT 06536, USA
The higher efficiency of HiV transmission via direct cell-cell contact over diffusion through the extra-cellular milieu is believed to be due
to the ability of HiV to efficiently coordinate several steps of the retroviral life cycle at contact sites. using the murine leukemia virus
(MlV) as a model retrovirus, we have shown that polarized assembly in infected cells contributes to the efficiency of viral spreading. in
addition, studying HiV cell-to-cell transmission, we observe a potent entry block for cell-free HiV in certain T cells that can be overcome
by the formation of an Env/CD4 dependent synapse. The ability of a virological synapse to overcome this block correlates directly to the
expression levels of CD4, but not co-receptor. High CD4 expression led to tighter synapses and transmission became more resistant to
neutralizing antibodies. As such, our mechanistic studies reveal details of how several retroviruses efficiently coordinate virus assembly and
entry at sites of cell-cell contact. Current work in the laboratory is devoted to identifying the cellular factors required for virus cell-to-cell
transmission and the isolation of small molecule inhibitors specifically interfering with virus transmission.
s o c i e t y f o r g e n e r a l
Microbiology