The Komagataeibacter europaeus GqqA is the prototype of a novel bifunctional N-Acyl-homoserine lactone acylase with prephenate dehydratase activity.
Werner, N., Petersen, K., Vollstedt, C., Garcia, P.P., Chow, J., Ferrer, M., Fernandez-Lopez, L., Falke, S., Perbandt, M., Hinrichs, W., Betzel, C., Streit, W.R.(2021) Sci Rep 11: 12255-12255
- PubMed: 34112823 
- DOI: https://doi.org/10.1038/s41598-021-91536-1
- Primary Citation of Related Structures:  
7ALZ, 7AM0 - PubMed Abstract: 
Previously, we reported the isolation of a quorum quenching protein (QQ), designated GqqA, from Komagataeibacter europaeus CECT 8546 that is highly homologous to prephenate dehydratases (PDT) (Valera et al. in Microb Cell Fact 15, 88. https://doi.org/10.1186/s12934-016-0482-y , 2016). GqqA strongly interfered with N-acyl-homoserine lactone (AHL) quorum sensing signals from Gram-negative bacteria and affected biofilm formation in its native host strain Komagataeibacter europaeus. Here we present and discuss data identifying GqqA as a novel acylase. ESI-MS-MS data showed unambiguously that GqqA hydrolyzes the amide bond of the acyl side-chain of AHL molecules, but not the lactone ring. Consistent with this observation the protein sequence does not carry a conserved Zn 2+ binding motif, known to be essential for metal-dependent lactonases, but in fact harboring the typical periplasmatic binding protein domain (PBP domain), acting as catalytic domain. We report structural details for the native structure at 2.5 Å resolution and for a truncated GqqA structure at 1.7 Å. The structures obtained highlight that GqqA acts as a dimer and complementary docking studies indicate that the lactone ring of the substrate binds within a cleft of the PBP domain and interacts with polar residues Y16, S17 and T174. The biochemical and phylogenetic analyses imply that GqqA represents the first member of a novel type of QQ family enzymes.
Organizational Affiliation: 
Laboratory for Structural Biology of Infection and Inflammation, Institute of Biochemistry and Molecular Biology, University Hamburg, C/O DESY, 22607, Hamburg, Germany.