6QBA

Crystal Structure of Retinol-Binding Protein 4 (RBP4) in complex with non-retinoid ligand A1120 and engineered binding scaffold

Summary for 6QBA

• Entry DOI: 10.2210/pdb6qba/pdb
• Descriptor: Retinol-binding protein 4, DNA-binding protein 7a, 2-[({4-[2-(trifluoromethyl)phenyl]piperidin-1-yl}carbonyl)amino]benzoic acid, ... (8 entities in total)
• Functional Keywords: lipocalin, rbp4, retinol binding protein, transport protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 2
• Total formula weight: 29281.70

Authors

Mlynek, G.,Brey, C.U.,Djinovic-Carugo, K.,Puehringer, D. (deposition date: 2018-12-20, release date: 2020-06-03, Last modification date: 2024-11-06)

Primary citation

Zajc, C.U.,Dobersberger, M.,Schaffner, I.,Mlynek, G.,Puhringer, D.,Salzer, B.,Djinovic-Carugo, K.,Steinberger, P.,De Sousa Linhares, A.,Yang, N.J.,Obinger, C.,Holter, W.,Traxlmayr, M.W.,Lehner, M.
A conformation-specific ON-switch for controlling CAR T cells with an orally available drug.
Proc.Natl.Acad.Sci.USA, 117:14926-14935, 2020

PubMed Abstract: Molecular ON-switches in which a chemical compound induces protein-protein interactions can allow cellular function to be controlled with small molecules. ON-switches based on clinically applicable compounds and human proteins would greatly facilitate their therapeutic use. Here, we developed an ON-switch system in which the human retinol binding protein 4 (hRBP4) of the lipocalin family interacts with engineered hRBP4 binders in a small molecule-dependent manner. Two different protein scaffolds were engineered to bind to hRBP4 when loaded with the orally available small molecule A1120. The crystal structure of an assembled ON-switch shows that the engineered binder specifically recognizes the conformational changes induced by A1120 in two loop regions of hRBP4. We demonstrate that this conformation-specific ON-switch is highly dependent on the presence of A1120, as demonstrated by an ∼500-fold increase in affinity upon addition of the small molecule drug. Furthermore, the ON-switch successfully regulated the activity of primary human CAR T cells in vitro. We anticipate that lipocalin-based ON-switches have the potential to be broadly applied for the safe pharmacological control of cellular therapeutics.

PubMed: 32554495
DOI: 10.1073/pnas.1911154117

Experimental method

X-RAY DIFFRACTION (1.8 Å)