@article{EckhardtAndersMuranyietal.2011,
  author    = {Eckhardt, Manon and Anders, Maria and Muranyi, Walter and Heilemann, Mike and Krijnse-Locker, Jacomine and M{\"u}ller, Barbara},
  title     = {A SNAP-Tagged Derivative of HIV-1-A Versatile Tool to Study Virus-Cell Interactions},
  series = {PLoS ONE},
  volume    = {6},
  journal   = {PLoS ONE},
  number    = {7},
  doi       = {10.1371/journal.pone.0022007},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-133534},
  pages     = {e22007},
  year      = {2011},
  abstract  = {Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and their maturation kinetics. Furthermore, several independent FP-tagged constructs have to be cloned and characterized in order to obtain spectral variations suitable for multi-color imaging setups. In contrast, the so-called SNAP-tag represents a genetically encoded non-fluorescent tag which mediates specific covalent coupling to fluorescent substrate molecules in a self-labeling reaction. Fusion of the SNAP-tag to the protein of interest allows specific labeling of the fusion protein with a variety of synthetic dyes, thereby offering enhanced flexibility for fluorescence imaging approaches. Here we describe the construction and characterization of the HIV derivative HIV(SNAP), which carries the SNAP-tag as an additional domain within the viral structural polyprotein Gag. Introduction of the tag close to the C-terminus of the matrix domain of Gag did not interfere with particle assembly, release or proteolytic virus maturation. The modified virions were infectious and could be propagated in tissue culture, albeit with reduced replication capacity. Insertion of the SNAP domain within Gag allowed specific staining of the viral polyprotein in the context of virus producing cells using a SNAP reactive dye as well as the visualization of individual virions and viral budding sites by stochastic optical reconstruction microscopy. Thus, HIV(SNAP) represents a versatile tool which expands the possibilities for the analysis of HIV-cell interactions using live cell imaging and sub-diffraction fluorescence microscopy.},
  language  = {en}
}
@article{MuranyiMalkuschMuelleretal.2013,
  author    = {Muranyi, Walter and Malkusch, Sebastian and M{\"u}ller, Barbara and Heilemann, Mike and Kr{\"a}usslich, Hans-Georg},
  title     = {Super-Resolution Microscopy Reveals Specific Recruitment of HIV-1 Envelope Proteins to Viral Assembly Sites Dependent on the Envelope C-Terminal Tail},
  series = {PLoS Pathogens},
  volume    = {9},
  journal   = {PLoS Pathogens},
  number    = {2},
  doi       = {10.1371/journal.ppat.1003198},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131235},
  pages     = {e1003198},
  year      = {2013},
  abstract  = {The inner structural Gag proteins and the envelope (Env) glycoproteins of human immunodeficiency virus (HIV-1) traffic independently to the plasma membrane, where they assemble the nascent virion. HIV-1 carries a relatively low number of glycoproteins in its membrane, and the mechanism of Env recruitment and virus incorporation is incompletely understood. We employed dual-color super-resolution microscopy visualizing Gag assembly sites and HIV-1 Env proteins in virus-producing and in Env expressing cells. Distinctive HIV-1 Gag assembly sites were readily detected and were associated with Env clusters that always extended beyond the actual Gag assembly site and often showed enrichment at the periphery and surrounding the assembly site. Formation of these Env clusters depended on the presence of other HIV-1 proteins and on the long cytoplasmic tail (CT) of Env. CT deletion, a matrix mutation affecting Env incorporation or Env expression in the absence of other HIV-1 proteins led to much smaller Env clusters, which were not enriched at viral assembly sites. These results show that Env is recruited to HIV-1 assembly sites in a CT-dependent manner, while Env\((\Delta CT)\) appears to be randomly incorporated. The observed Env accumulation surrounding Gag assemblies, with a lower density on the actual bud, could facilitate viral spread in vivo. Keeping Env molecules on the nascent virus low may be important for escape from the humoral immune response, while cell-cell contacts mediated by surrounding Env molecules could promote HIV-1 transmission through the virological synapse.},
  language  = {en}
}