9DIR

Cryo-EM structure of the heme/hemoglobin transporter ChuA, in complex with de novo designed binder G7

This is a non-PDB format compatible entry.

Summary for 9DIR

• Entry DOI: 10.2210/pdb9dir/pdb
• Related: 9DHE
• EMDB information: 46916
• Descriptor: ChuA binding protein G7, Outer membrane heme/hemoglobin receptor (2 entities in total)
• Functional Keywords: tonb-dependent transporter, chua, heme, hemoglobin, outer-membrane, de novo designed protein, binding protein, transport protein
• Biological source: synthetic construct; More
• Total number of polymer chains: 2
• Total formula weight: 85020.07

Authors

Fox, D.,Venugopal, H.,Lupton, C.J.,Spicer, B.A.,Grinter, R. (deposition date: 2024-09-05, release date: 2025-05-21, Last modification date: 2025-07-23)

Primary citation

Fox, D.R.,Asadollahi, K.,Samuels, I.,Spicer, B.A.,Kropp, A.,Lupton, C.J.,Lim, K.,Wang, C.,Venugopal, H.,Dramicanin, M.,Knott, G.J.,Grinter, R.
Inhibiting heme piracy by pathogenic Escherichia coli using de novo-designed proteins.
Nat Commun, 16:6066-6066, 2025

PubMed Abstract: Iron is an essential nutrient for most bacteria and is often growth-limiting during infection, due to the host sequestering free iron as part of the innate immune response. To obtain the iron required for growth, many bacterial pathogens encode transporters capable of extracting the iron-containing cofactor heme directly from host proteins. Pathogenic E. coli and Shigella spp. produce the outer membrane transporter ChuA, which binds host hemoglobin and extracts its heme cofactor, before importing heme into the cell. Heme extraction by ChuA is a dynamic process, with the transporter capable of rapidly extracting heme from hemoglobin in the absence of an external energy source, without forming a stable ChuA-hemoglobin complex. In this work, we utilise a combination of structural modelling, Cryo-EM, X-ray crystallography, mutagenesis, and phenotypic analysis to understand the mechanistic detail of this process. Based on this understanding we utilise artificial intelligence-based protein design to create binders capable of inhibiting E. coli growth by blocking hemoglobin binding to ChuA. By screening a limited number of these designs, we identify several binders that inhibit E. coli growth at low nanomolar concentrations, without experimental optimisation. We determine the structure of a subset of these binders, alone and in complex with ChuA, demonstrating that they closely match the computational design. This work demonstrates the utility of de novo-designed proteins for inhibiting bacterial nutrient uptake and uses a workflow that could be applied to integral membrane proteins in other organisms.

PubMed: 40634285
DOI: 10.1038/s41467-025-60612-9

Experimental method

ELECTRON MICROSCOPY (2.97 Å)