Parallel force assay for protein-protein interactions

PLoS One. 2014 Dec 29;9(12):e115049. doi: 10.1371/journal.pone.0115049. eCollection 2014.

Abstract

Quantitative proteome research is greatly promoted by high-resolution parallel format assays. A characterization of protein complexes based on binding forces offers an unparalleled dynamic range and allows for the effective discrimination of non-specific interactions. Here we present a DNA-based Molecular Force Assay to quantify protein-protein interactions, namely the bond between different variants of GFP and GFP-binding nanobodies. We present different strategies to adjust the maximum sensitivity window of the assay by influencing the binding strength of the DNA reference duplexes. The binding of the nanobody Enhancer to the different GFP constructs is compared at high sensitivity of the assay. Whereas the binding strength to wild type and enhanced GFP are equal within experimental error, stronger binding to superfolder GFP is observed. This difference in binding strength is attributed to alterations in the amino acids that form contacts according to the crystal structure of the initial wild type GFP-Enhancer complex. Moreover, we outline the potential for large-scale parallelization of the assay.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA / metabolism
  • Green Fluorescent Proteins / immunology
  • Protein Binding
  • Protein Interaction Mapping / methods*
  • Single-Domain Antibodies / immunology*

Substances

  • Single-Domain Antibodies
  • Green Fluorescent Proteins
  • DNA

Grants and funding

Funding was provided by the Deutsche Forschungsgemeinschaft SFB 1032-A01 (HEG) and SPP 1623, LE 721/13-1 (HL) as well as a European Research Council Advanced Grant (HEG). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. KK and KL are grateful to the Elite Network of Bavaria (International Doctorate Program NanoBioTechnology) for doctoral fellowships. DA, KK and KL thank Nanosystems Initiative Munich for support.