Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Aug 29:9:933400.
doi: 10.3389/fmolb.2022.933400. eCollection 2022.

MutDock: A computational docking approach for fixed-backbone protein scaffold design

Affiliations

MutDock: A computational docking approach for fixed-backbone protein scaffold design

Varun M Chauhan et al. Front Mol Biosci. .

Abstract

Despite the successes of antibodies as therapeutic binding proteins, they still face production and design challenges. Alternative binding scaffolds of smaller size have been developed to overcome these issues. A subset of these alternative scaffolds recognizes target molecules through mutations to a set of surface resides, which does not alter their backbone structures. While the computational design of antibodies for target epitopes has been explored in depth, the same has not been done for alternative scaffolds. The commonly used dock-and-mutate approach for binding proteins, including antibodies, is limited because it uses a constant sequence and structure representation of the scaffold. Docking fixed-backbone scaffolds with a varied group of surface amino acids increases the chances of identifying superior starting poses that can be improved with subsequent mutations. In this work, we have developed MutDock, a novel computational approach that simultaneously docks and mutates fixed backbone scaffolds for binding a target epitope by identifying a minimum number of hydrogen bonds. The approach is broadly divided into two steps. The first step uses pairwise distance alignment of hydrogen bond-forming areas of scaffold residues and compatible epitope atoms. This step considers both native and mutated rotamers of scaffold residues. The second step mutates clashing variable interface residues and thermodynamically unfavorable residues to create additional strong interactions. MutDock was used to dock two scaffolds, namely, Affibodies and DARPins, with ten randomly selected antigens. The energies of the docked poses were minimized and binding energies were compared with docked poses from ZDOCK and HADDOCK. The top MutDock poses consisted of higher and comparable binding energies than the top ZDOCK and HADDOCK poses, respectively. This work contributes to the discovery of novel binders based on smaller-sized, fixed-backbone protein scaffolds.

Keywords: binding energy; force field; hydrogen bonds; protein docking; protein scaffold.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Examples of alternative binding scaffolds. Depicted are (A) Affibody (PDB: 3MZW) and (B) DARPin (PDB: 6FPA) structures. Their variable residues that mutate to bind target proteins are colored in pink.
FIGURE 2
FIGURE 2
MutDock workflow. MutDock can be divided into two main steps: pose identification (panels A–C) and pose validation (panel D). Step (A) PBRs are identified for all paratope residues and all other rotamers of variable residues (shown in pink). Similarly, EBAs are identified for all epitope residues. Step (B) Pairwise distance calculations within the sets of PBRs and EBAs. Step (C) Pairwise distance matching between PBR pairs and EBA pairs to identify groups of compatible low entropy interactions. Step (D) Each pose from Step C is passed through steric clash filters, and clashing variable side chains are mutated.
FIGURE 3
FIGURE 3
PBR and EBA pairwise distance and angle calculations. PBRs generated for paratope ASP and ARG. EBA identified for epitope TRP and GLU. The interactions being considered here are H-bonds between 1) ASP and TRP and 2) ARG and GLU. For the two interactions to be compatible, |D1 – D2| < 1.8 Å, |∠PBR1p - ∠EBA1p| < 70°, |∠PBR2p - ∠EBA2p| < 70°, |∠PBR1s - ∠EBA1a| < 70°, and |∠PBR2s - ∠EBA2a| < 70°.
FIGURE 4
FIGURE 4
Percentage frequencies of amino acids in design mutations before and after clash mutations. In the clash mutations, aromatic amino acids which have larger side chains and lower flexibilities were mutated to smaller polar amino acids and LEU.
FIGURE 5
FIGURE 5
Example design and clash mutations in three MutDock designs. Design mutations are shown in pink, clash mutations are shown in dark cyan, and H-bonds are shown in broken green lines. (A) 1JRH-affibody. Native residue 10ARG and design mutations ARG28TRP andALA17ASP make H-bonds with 91GLU, 43ASN, and 46TRP, respectively. Clash mutation TYR13ASP makes H-bond with 37LYS. Clash mutation TYR35LEU makes hydrophobic interaction with 39TYR. (B) 4AL8-DARPin. Design mutations VAL102GLU, GLN80ASN, and MET101TYR make H-bonds with 69ASN, 20HIS, and 67PRO, respectively. Clash mutation TRP71LEU makes hydrophobic interaction with 20HIS. (C) 3BDY-affibody. Design mutations ARG28ASN, TYR13ASP, and LEU18ARG make H-bonds with 76GLN, 80GLU, and 31GLU, respectively. Clash mutation TYR35LEU makes hydrophobic interaction with 78ILE.
FIGURE 6
FIGURE 6
Top Rosetta-predicted computational binding energies of poses from the 20 docking simulations performed using ZDOCK, MutDock, HADDOCK, and a combination approach of HADDOCK with top MutDock scaffold.

Similar articles

Cited by

References

    1. Adolf-Bryfogle J., Kalyuzhniy O., Kubitz M., Weitzner B. D., Hu X., Adachi Y., et al. (2018). RosettaAntibodyDesign (RAbD): a general framework for computational antibody design. PLoS Comput. Biol. 14, e1006112. 10.1371/journal.pcbi.1006112 - DOI - PMC - PubMed
    1. Alford R. F., Leaver-Fay A., Jeliazkov J. R., O’Meara M. J., DiMaio F. P., Park H., et al. (2017). The Rosetta all-atom energy function for macromolecular modeling and design. J. Chem. Theory Comput. 13, 3031–3048. 10.1021/acs.jctc.7b00125 - DOI - PMC - PubMed
    1. Almagro J. C., Pedraza-Escalona M., Arrieta H. I., Pérez-Tapia S. M. (2019). Phage display libraries for antibody therapeutic discovery and development. Antibodies 8, 44. 10.3390/antib8030044 - DOI - PMC - PubMed
    1. Alsultan A. M., Chin D. Y., Howard C. B., de Bakker C. J., Jones M. L., Mahler S. M. (2016). Beyond antibodies: development of a novel protein scaffold based on human chaperonin 10. Sci. Rep. 6, 37348. 10.1038/srep37348 - DOI - PMC - PubMed
    1. Altunay B., Morgenroth A., Beheshti M., Vogg A., Wong N. C. L., Ting H. H., et al. (2021). HER2-directed antibodies, affibodies and nanobodies as drug-delivery vehicles in breast cancer with a specific focus on radioimmunotherapy and radioimmunoimaging. Eur. J. Nucl. Med. Mol. Imaging 48, 1371–1389. 10.1007/s00259-020-05094-1 - DOI - PMC - PubMed

LinkOut - more resources

-