Dinoflagellate/viral nucleoproteins (DVNPs) are a family of positively-charged,
DNA-binding nucleoproteins
Nucleoproteins are proteins conjugated with nucleic acids (either DNA or RNA). Typical nucleoproteins include ribosomes, nucleosomes and viral nucleocapsid proteins.
Structures
Nucleoproteins tend to be positively charged, facilitating inte ...
found exclusively in
dinoflagellates and
Nucleocytoviricota. It serves to
compact DNA in these organisms.
The proteins are known to pack DNA more tightly than histones do. When expressed in eukaryotes that possess histones, they displace
nucleosome
A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamen ...
s and impair translation. This action is thought to be one of the driving forces for dinoflagellates to switch to this protein instead of
histone for packaging. Some dinoflagellates have further switched to
dinoflagellate histone-like proteins
In molecular biology, bacterial DNA binding proteins are a family of small, usually basic proteins of about 90 residues that bind DNA and are known as histone-like proteins. Since bacterial binding proteins have a diversity of functions, it has be ...
(HLPs) for packaging.
The version of DVNPs in dinoflagellates have a variable N-terminal tail with a
nuclear localization signal. It also has many
phosphorylation sites
In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...
, a feature not seen in viral counterparts. The fixed C-terminal domain may have a helix-turn-helix fold.
References
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DNA-binding proteins