Molecular features of steroid-binding antidins and their use for assaying serum progesterone

PLoS One. 2019 Feb 20;14(2):e0212339. doi: 10.1371/journal.pone.0212339. eCollection 2019.

Abstract

Chicken avidin (Avd) and streptavidin from Streptomyces avidinii are extensively used in bionanotechnology due to their extremely tight binding to biotin (Kd ~ 10-15 M for chicken Avd). We previously reported engineered Avds known as antidins, which have micro- to nanomolar affinities for steroids, non-natural ligands of Avd. Here, we report the 2.8 Å X-ray structure of the sbAvd-2 (I117Y) antidin co-crystallized with progesterone. We describe the creation of new synthetic phage display libraries and report the experimental as well as computational binding analysis of progesterone-binding antidins. We introduce a next-generation antidin with 5 nM binding affinity for progesterone, and demonstrate the use of antidins for measuring progesterone in serum samples. Our data give insights on how to engineer and alter the binding preferences of Avds and to develop better molecular tools for modern bionanotechnological applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avidin / chemistry
  • Avidin / metabolism*
  • Binding Sites
  • Biological Assay
  • Biotin / chemistry
  • Biotin / metabolism*
  • Dogs
  • Ligands
  • Models, Molecular
  • Progesterone / blood*
  • Progesterone / chemistry
  • Progesterone / metabolism*
  • Protein Binding

Substances

  • Ligands
  • Avidin
  • Progesterone
  • Biotin

Grants and funding

This work was supported by grant funding from the Academy of Finland (257814 (M.S.J.), 272283 (M.S.J.), 263540 (V.P.H), 290506 (V.P.H.), 261285 (M.S.K.), and 272288 (M.S.K.)); Sigrid Juselius Foundation; Joe, Pentti and Tor Borg Memorial Fund; Orion Research Foundation sr; Academy of Finland FIRI program (141398); and Åbo Akademi Center of Excellence in Cell Stress and Aging. Fimlab Laboratories (Tampere, Finland) provided support in the form of salaries for author VPH and research materials for the group led by VPH. Fimlab and the other funders had no influence in the study design, data collection and analysis, decision to publish or preparation of the manuscript.