Putative transmembrane domain more commonly known as Non-structural Protein 6 (NSP6) is one of the two non-structural proteins that gene 11 in
rotavirus encodes for alongside
NSP5. NSP6 is composed of six
transmembrane domains and a C terminal tail. In contrast to the other rotavirus non-structural proteins, NSP6 was found to have a high rate of turnover, being completely degraded within 2 hours of synthesis. NSP6 was found to be a sequence-independent
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...
binding protein, with similar affinities for
ssRNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
and
dsRNA
It has been determined that NSP6 has three crucial functions that it conducts. As messages flow among the replication
organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the ...
and the
endoplasmic reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
(ER) NSP6 acts as a filter. In this case, NSP6 hinders the access of ER luminal proteins to the DMVs but permits the passing of
lipids. Next NSP6 arranges DMV clusters, since the DMV clusters are organized by NSP6 it can reconstruct them with LD-derived Lipids. Lastly, through LD-tethering complex DFCP1-RAB18 intervenes in the contact of
lipid droplets (LDs).
Since NSP6 is one of two non-structural proteins that gene 11 codes for NSP6 is found in both α and β
coronavirus
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the com ...
es and produces
autophagosomes. While NSP6 is found to produce a substantial amount of autophagosomes, through the analysis of
MAP1LC3B puncta it is observed that autophagosomes produced by NSP6 are much smaller in size. As indicated by the statistical analysis of
WIPI2 puncta the size of NSP6-produced autophagosomes is restricted at
omegasome formation. The small size of these autophagosomes inhibits the transportation of viral components to
lysosomes and this could aid in coronavirus infection.
References
{{Viral proteins
Rotaviruses
Viral nonstructural proteins