9PRB

Crystal structure of the N-terminal domain of the A subunit of the Bacillus cereus GerI germinant receptor

Summary for 9PRB

• Entry DOI: 10.2210/pdb9prb/pdb
• Descriptor: Spore germination protein GerIA, ACETATE ION (3 entities in total)
• Functional Keywords: germinant receptor; germination; bacillus, protein transport
• Biological source: Bacillus cereus ATCC 14579
• Total number of polymer chains: 3
• Total formula weight: 90646.95

Authors

Li, Y.,Hao, B. (deposition date: 2025-07-23, release date: 2026-03-25, Last modification date: 2026-04-08)

Primary citation

Li, Y.,Ow-Young-Villarreal, G.,Pustovalova, Y.,Bailey, D.M.D.,Yarrow, J.,Korza, G.,Ye, F.,Erlandsen, H.,Setlow, P.,Christie, G.,Hao, B.
Structural and functional analysis of the Bacillus cereus GerI inosine-responsive spore germinant receptor.
Mbio, :e0010826-e0010826, 2026

PubMed Abstract: Bacterial endospores are metabolically dormant yet can rapidly return to vegetative growth upon exposure to nutrients through the process of germination. Spore germination is triggered by specific chemical nutrients binding to cognate germinant receptors (GRs) in spores' inner membrane. These GRs function as ligand-gated ion channels and are composed of clusters of at least three subunits. Given their central role in germinant recognition and discrimination, elucidating 3D structures of GR subunits is a key part of efforts to understand the mechanism(s) of spore germination. Here, we present the crystal structure of the N-terminal domain of the GerIA protein (GerIA), a component of the inosine-responsive GerI GR. GerIA adopts a conformation homologous to substrate-binding proteins in bacterial ABC transporters. NMR chemical shift perturbation and site-directed mutagenesis identified GerIA residues potentially involved in inosine binding or critical for germinosome assembly in spores, modification of which abrogated inosine-induced germination. Molecular modeling and mutagenesis additionally identified residues in the GerIB subunit forming germinant and cation-binding sites. GerQ, the second GR that contributes to inosine germination in spores, was capable of complementing hypomorphic alleles in several instances, demonstrating cooperative restoration of function despite being incapable of initiating germination to inosine in null spores. Collectively, our results provide new insights into GR subunit function and the molecular basis of the germinative response to inosine.

PubMed: 41891750
DOI: 10.1128/mbio.00108-26

Experimental method

X-RAY DIFFRACTION (2.8 Å)