4hv0

Publication Abstract from PubMed

The structural and functional analysis of the protein AvtR, coded by Acidianus filamentous virus 6 (AFV6) that infects the archaeal genus Acidianus, revealed its unusual structure and involvement in transcriptional regulation of several viral genes. The crystal structure of AvtR (100 amino acids) at 2.6 A resolution shows that it is constituted of a repeated ribbon-helix-helix (RHH) motif, which is found in a large family of bacterial transcriptional regulators. The known RHH proteins form dimers that interact with DNA using their ribbon to create a central beta-sheet. The repeated RHH motifs of AvtR superpose well on such dimers, but its central sheet contains an extra strand, suggesting either conformational changes or a different mode of DNA binding. SELEX experiments combined with systematic mutational and computational analysis of the predicted site revealed 8 potential AvtR targets in the AFV6 genome. Two of these targets were studied in detail and the complex role of AvtR in the transcriptional regulation of viral genes was established. Repressing transcription from its own gene, gp29, AvtR can also act as an activator of another gene, gp30. Its binding sites are distant from both genes' TATA-boxes and the mechanism of AvtR-dependent regulation appears to include protein oligomerisation starting from the protein's initial binding sites. Many RHH transcriptional regulators of archaeal viruses could share this regulatory mechanism.

Structure and function of AvtR, a novel transcriptional regulator from a hyperthermophilic archaeal lipothrixvirus.,Peixeiro N, Keller J, Collinet B, Leulliot N, Campanacci V, Cortez D, Cambillau C, Nitta KR, Vincentelli R, Forterre P, Prangishvili D, Sezonov G, van Tilbeurgh H J Virol. 2012 Oct 10. PMID:23055559^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.