The HIV-1 viral infectivity factor (Vif) is required for productive infection of non-permissive cells, including most natural HIV-1 targets, where it counteracts the antiviral activities of the cellular cytosine deaminases APOBEC-3G (A3G) and A3F. Vif is a multimeric protein and the conserved proline-rich domain (161)PPLP(164) regulating Vif oligomerization is crucial for its function and viral...

Translocation of bacteria into the mesenteric fat during intestinal inflammation and the expression of functional TLR1-9 in murine preadipocytes and adipocytes suggest an active role for these cells in innate immunity. The present study focuses on nucleotide oligomerization domains 1 and 2 representing intracellular pattern recognition receptors that sense motifs derived from bacterial peptidog...

Tailed DNA bacteriophages assemble empty procapsids that are subsequently filled with the viral genome by means of a DNA packaging machine situated at a special fivefold vertex. The packaging machine consists of a "small terminase" and a "large terminase" component. One of the functions of the small terminase is to initiate packaging of the viral genome, whereas the large terminase is responsib...

Interferon stimulation of cells can activate several hundred target genes, many of which are required for antiviral protection. Promoter binding of tyrosine-phosphorylated (activated) Stat1 dimers is essential for gene induction, a process that often entails the oligomerization of Stat1 dimers via interactions of their aminoterminal domains. The mutation of a single residue (F77) in the N-domai...

The synaptic vesicle protein synaptotagmin I has been proposed to serve as a Ca(2+) sensor for rapid exocytosis. Synaptotagmin spans the vesicle membrane once and possesses a cytoplasmic domain largely comprised of two C2 domains designated C2A and C2B. We have determined how deep the Ca(2+)-binding loops of Ca(2+).C2A penetrate into the lipid bilayer and report mutations in synaptotagmin that ...

The effects of guanine nucleotides on the intrinsic and extrinsic fluorescence properties of dynamin were assessed. The intrinsic Trp (tryptophan) fluorescence spectra of purified recombinant dynamin-1 and -2 were very similar, with a maximum at 332 nm. Collisional quenching by KI was weak (approximately 30%), suggesting that the majority of Trp residues are buried. Binding of guanine nucleotid...

The human herpes simplex virus type 1 regulatory protein ICP4 binds DNA as a dimer and forms a single protein-DNA complex (A complex) with short DNA probes. ICP4 oligomerized in a DNA-dependent manner, forming two or more protein-DNA complexes with longer DNA fragments containing a single DNA binding site. When resolved electrophoretically, one or more low-mobility DNA-protein complexes follow ...