Dataset Information

Small-Angle X-ray Scattering Models of APOBEC3B Catalytic Domain in a Complex with a Single-Stranded DNA Inhibitor.

ABSTRACT: In normal cells APOBEC3 (A3A-A3H) enzymes as part of the innate immune system deaminate cytosine to uracil on single-stranded DNA (ssDNA) to scramble DNA in order to give protection against a range of exogenous retroviruses, DNA-based parasites, and endogenous retroelements. However, some viruses and cancer cells use these enzymes, especially A3A and A3B, to escape the adaptive immune response and thereby lead to the evolution of drug resistance. We have synthesized first-in-class inhibitors featuring modified ssDNA. We present models based on small-angle X-ray scattering (SAXS) data that (1) confirm that the mode of binding of inhibitor to an active A3B C-terminal domain construct in the solution state is the same as the mode of binding substrate to inactive mutants of A3A and A3B revealed in X-ray crystal structures and (2) give insight into the disulfide-linked inactive dimer formed under the oxidizing conditions of purification.

SUBMITTER: Barzak FM

PROVIDER: S-EPMC7918907 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Small-Angle X-ray Scattering Models of APOBEC3B Catalytic Domain in a Complex with a Single-Stranded DNA Inhibitor.

Barzak Fareeda M FM Ryan Timothy M TM Kvach Maksim V MV Kurup Harikrishnan M HM Aihara Hideki H Harris Reuben S RS Filichev Vyacheslav V VV Harjes Elena E Jameson Geoffrey B GB

Viruses 20210212 2

In normal cells APOBEC3 (A3A-A3H) enzymes as part of the innate immune system deaminate cytosine to uracil on single-stranded DNA (ssDNA) to scramble DNA in order to give protection against a range of exogenous retroviruses, DNA-based parasites, and endogenous retroelements. However, some viruses and cancer cells use these enzymes, especially A3A and A3B, to escape the adaptive immune response and thereby lead to the evolution of drug resistance. We have synthesized first-in-class inhibitors fea ...[more]

PMID: 33673243

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Project description:BACKGROUND:Genome sequencing projects have expanded the gap between the amount of known protein sequences and structures. The limitations of current high resolution structure determination methods make it unlikely that this gap will disappear in the near future. Small angle X-ray scattering (SAXS) is an established low resolution method for routinely determining the structure of proteins in solution. The purpose of this study is to develop a method for the efficient calculation of accurate SAXS curves from coarse-grained protein models. Such a method can for example be used to construct a likelihood function, which is paramount for structure determination based on statistical inference. RESULTS:We present a method for the efficient calculation of accurate SAXS curves based on the Debye formula and a set of scattering form factors for dummy atom representations of amino acids. Such a method avoids the computationally costly iteration over all atoms. We estimated the form factors using generated data from a set of high quality protein structures. No ad hoc scaling or correction factors are applied in the calculation of the curves. Two coarse-grained representations of protein structure were investigated; two scattering bodies per amino acid led to significantly better results than a single scattering body. CONCLUSION:We show that the obtained point estimates allow the calculation of accurate SAXS curves from coarse-grained protein models. The resulting curves are on par with the current state-of-the-art program CRYSOL, which requires full atomic detail. Our method was also comparable to CRYSOL in recognizing native structures among native-like decoys. As a proof-of-concept, we combined the coarse-grained Debye calculation with a previously described probabilistic model of protein structure, TorusDBN. This resulted in a significant improvement in the decoy recognition performance. In conclusion, the presented method shows great promise for use in statistical inference of protein structures from SAXS data.

Dataset Information

Small-Angle X-ray Scattering Models of APOBEC3B Catalytic Domain in a Complex with a Single-Stranded DNA Inhibitor.

Publications

Small-Angle X-ray Scattering Models of APOBEC3B Catalytic Domain in a Complex with a Single-Stranded DNA Inhibitor.

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