InterPro domain: IPR018004

The amino-terminal module of the poxvirus D6R/NIR proteins defines a novel conserved DNA-binding domain (the KilA-N domain) that is found in a wide range of proteins of large bacterial and eukaryotic DNA viruses [ 1 ]. Putative proteins with homology to the KilA-N domain have also been identified in Maverick transposable elements of the parabasalid protozoa Trichomonas vaginalis [ 2 ]. The KilA-N domain has been suggested to be homologous to the fungal DNA-binding APSES domain (see PDOC51299 ). In all proteins shown to contain the KilA-N domain, it occurs at the extreme amino terminus accompanied by a wide range of distinct carboxy-terminal domains. These carboxy-terminal modules may be enzymes, such as the nuclease domains, or might mediate additional, specific interactions with nucleic acids or proteins, like the RING (see PDOC00449 ) or CCCH fingers in the poxviruses [ 3 ]. The KilA-N domain is predicted to adopt an alpha-beta fold with four conserved strands and at least two conserved helices [ 3 ]. Some proteins known to contain a KilA-N domain are listed below:

• Bacteriophage P1 protein kilA ( P19653 ).
• Fowlpox virus (FPV) protein FPV236 ( P14365 ).
• Trichomonas vaginalis G3 Putative uncharacterised protein ( A2D8C0 ).
• Vaccinia virus hypothetical 21.7kDa HindIII-C protein ( P17366 ).

1. Extensive domain shuffling in transcription regulators of DNA viruses and implications for the origin of fungal APSES transcription factors. Genome Biol. 3, RESEARCH0012
2. Mavericks, a novel class of giant transposable elements widespread in eukaryotes and related to DNA viruses. Gene 390, 3-17