Biology Reference
In-Depth Information
the panhandle and thus making the 3´ terminus of RNA available for
the viral polymerase.
The phenomenon of hantaviral N protein oligomerization was
discovered simultaneously by research groups from Finland
16
and the
United States.
17
It was found that the N protein can form stable
trimers in both viral particles and infected cells, and it was suggested
that these trimers represent intermediates in the process of N protein
oligomerization and RNP formation. An interaction between N pro-
tein monomers appeared to be non-covalent and electrostatic.
16
The studies that followed have further characterized the interacting
domains and pinpointed aa residues that are crucial for the interac-
tion.
18-21
The oligomerization of the hantaviral N protein was ana-
lyzed using a combination of computer modeling with the following
in vitro
techniques: peptide and alanine scanning, a mammalian two-
hybrid assay, and an immunofluorescence assay. It was shown that
both termini of the molecule contribute to the N-N-interaction. The
data supported a “head-to-head, tail-to-tail” model, which suggests
that the N-N-interaction is a two-step process involving an initial
interplay between the N-terminal domains followed by a consolidat-
ing interaction between the C-terminal domains. The N-terminal
tri/oligomerization domain of the hantaviral N protein was found to
fold into a coiled-coil structure.
17,21,22
The results obtained were con-
sistent with the existence of an anti-parallel coiled-coil, and several aa
residues (L44, L58 and I51), all located at the “a” positions of hep-
tad repeats, were found to be especially important for the N-N-inter-
action.
21
The consolidating interaction between the C-terminal
domains were found to occur via protrusions of two alpha-helices and
the shared hydrophobic space formed by amino acid residues 380-
IILLF-384 and 413-LI-414.
19
All hantaviruses seemed to have the
same, or very similar, structure of the terminal domains, which sug-
gested a genus-specific mode of the N protein tri/oligomerization.
Experiments with
Hantaviral minigenomes
demonstrated that
functional L and N proteins are the only viral proteins needed for repli-
cation and transcription.
23
Both proteins are at least partially colocal-
ized at the Golgi compartment
24
and most probably interact with each
other in determining the location of RNA synthesis of hantaviruses
