Structural insights into a high affinity nanobody:antigen complex by homology modelling.

Area of Science:

• Oral microbiology
• Immunology
• Structural biology

Background:

• Porphyromonas gingivalis is a key pathogen in periodontitis.
• The cysteine protease RgpB, secreted by P. gingivalis, is a potential diagnostic target.
• A nanobody, VHH7, exhibits high affinity and specificity for RgpB.

Purpose of the Study:

• To build a homology model of the VHH7 nanobody.
• To identify key residues involved in the VHH7-RgpB interaction.
• To provide insights for developing targeted RgpB therapies.

Main Methods:

• Homology modeling of VHH7 nanobody.
• Identification of complementarity determining regions (CDRs) and RgpB epitope residues.
• Information-driven flexible docking using the HADDOCK server.

Main Results:

• The VHH7 homology model and VHH7:RgpB complex were analyzed.
• The RgpB epitope was located within its immunoglobulin-like domain.
• Key residue pairs at the paratope:epitope interface crucial for complex stability were identified.

Conclusions:

• The study provides structural insights into the VHH7-RgpB interaction.
• This knowledge can guide the design of specific RgpB-targeting antibody-drug conjugates.
• The findings support RgpB as a viable target for Porphyromonas gingivalis diagnostics and therapeutics.