9C4O

Cryo-EM structure of PqqU with ligand PQQ

Summary for 9C4O

• Entry DOI: 10.2210/pdb9c4o/pdb
• EMDB information: 45192
• Descriptor: Pyrroloquinoline quinone transporter, CALCIUM ION, PYRROLOQUINOLINE QUINONE, ... (4 entities in total)
• Functional Keywords: tond-dependent, outer membrane, transporter, pqq uptake, membrane protein
• Biological source: Escherichia coli BW25113
• Total number of polymer chains: 1
• Total formula weight: 78771.45

Authors

Munder, F.,Venugopal, H.,Grinter, R. (deposition date: 2024-06-04, release date: 2024-06-19, Last modification date: 2025-08-13)

Primary citation

Munder, F.,Voutsinos, M.,Hantke, K.,Venugopal, H.,Grinter, R.
High-affinity PQQ import is widespread in Gram-negative bacteria.
Sci Adv, 11:eadr2753-eadr2753, 2025

PubMed Abstract: Pyrroloquinoline quinone (PQQ) is a soluble redox cofactor used by diverse bacteria. Many Gram-negative bacteria that encode PQQ-dependent enzymes do not produce it and instead obtain it from the environment. To achieve this, uses the TonB-dependent transporter PqqU as a high-affinity PQQ importer. Here, we show that PqqU binds PQQ with high affinity and determine the high-resolution structure of the PqqU-PQQ complex, revealing that PqqU undergoes conformational changes in PQQ binding to capture the cofactor in an internal cavity. We show that these conformational changes preclude the binding of a bacteriophage, which targets PqqU as a cell surface receptor. Guided by the PqqU-PQQ structure, we identify amino acids essential for PQQ import and leverage this information to map the presence of PqqU across Gram-negative bacteria. This reveals that PqqU is encoded by Gram-negative bacteria from at least 22 phyla occupying diverse habitats, indicating that PQQ is an important cofactor for bacteria that adopt diverse lifestyles and metabolic strategies.

PubMed: 40446051
DOI: 10.1126/sciadv.adr2753

Experimental method

ELECTRON MICROSCOPY (1.99 Å)