2le2
From Proteopedia
Novel dimeric structure of phage phi29-encoded protein p56: Insights into Uracil-DNA glycosylase inhibition
Structural highlights
FunctionP56_BPPH2 Inhibits the host uracil-DNA glycosylase (UDG), an enzyme which removes uracil residues from DNA by the base excision repair. Interacts with host uracil-DNA glycosylase and prevents the latter from binding to DNA. Since the viral DNA polymerase efficiently incorporates dUMP into DNA, the virus needs to prevent the deleterious effect caused by host UDG when it eliminates uracil residues present in the viral genome.[1] [2] [3] Publication Abstract from PubMedProtein p56 encoded by the Bacillus subtilis phage 29 inhibits the host uracil-DNA glycosylase (UDG) activity. To get insights into the structural basis for this inhibition, the NMR solution structure of p56 has been determined. The inhibitor defines a novel dimeric fold, stabilized by a combination of polar and extensive hydrophobic interactions. Each polypeptide chain contains three stretches of anti-parallel beta-sheets and a helical region linked by three short loops. In addition, microcalorimetry titration experiments showed that it forms a tight 2:1 complex with UDG, strongly suggesting that the dimer represents the functional form of the inhibitor. This was further confirmed by the functional analysis of p56 mutants unable to assemble into dimers. We have also shown that the highly anionic region of the inhibitor plays a significant role in the inhibition of UDG. Thus, based on these findings and taking into account previous results that revealed similarities between the association mode of p56 and the phage PBS-1/PBS-2-encoded inhibitor Ugi with UDG, we propose that protein p56 might inhibit the enzyme by mimicking its DNA substrate. Novel dimeric structure of phage {phi}29-encoded protein p56: insights into uracil-DNA glycosylase inhibition.,Asensio JL, Perez-Lago L, Lazaro JM, Gonzalez C, Serrano-Heras G, Salas M Nucleic Acids Res. 2011 Sep 2. PMID:21890898[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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