The human APOBEC3G (A3G) protein is a cellular polynucleotide cytidine deaminase that acts as a host restriction factor of retroviruses, including HIV-1 and various transposable elements. Recently, three NMR and two crystal structures of the catalytic deaminase domain of A3G have been reported, but these are in disagreement over the conformation of a terminal beta-strand, beta2, as well as the identification of a putative DNA binding site. We here report molecular dynamics simulations with all of the solved A3G catalytic domain structures, taking into account solubility enhancing mutations that were introduced during derivation of three out of the five structures. In the course of these simulations, we observed a general trend towards increased definition of the beta2 strand for those structures that have a distorted starting conformation of beta2. Solvent density maps around the protein as calculated from MD simulations indicated that this distortion is dependent on preferential hydration of residues within the beta2 strand. We also demonstrate that the identification of a pre-defined DNA binding site is prevented by the inherent flexibility of loops that determine access to the deaminase catalytic core. We discuss the implications of our analyses for the as yet unresolved structure of the full-length A3G protein and its biological functions with regard to hypermutation of DNA.
Pubmed ID: 20635000 RIS Download
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A user-sponsored molecular visualization software system on an open-source foundation. The software has the capabilities to view, render, animate, export, present and develop three dimensional molecular structures.
View all literature mentionsA software package created to perform molecular dynamics. It is primarily designed for biochemical molecules like proteins, lipids and nucleic acids that have many complicated bonded interactions, but it can also be used for research on non-biological systems, such as polymers.
View all literature mentionsCell line HEK293T is a Transformed cell line with a species of origin Homo sapiens (Human)
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