7D53

SpuA mutant - H221N with Glu

Summary for 7D53

• Entry DOI: 10.2210/pdb7d53/pdb
• Descriptor: Probable glutamine amidotransferase, MAGNESIUM ION, GLUTAMIC ACID, ... (4 entities in total)
• Functional Keywords: spua, gama-glutamyl-gama-aminobutyrate hydrolase, glutamine amidotransferase, pseudomonas aeruginosa pao1., hydrolase
• Biological source: Pseudomonas aeruginosa PAO1
• Total number of polymer chains: 4
• Total formula weight: 106614.14

Authors

Chen, Y.,Zhang, Q.,Bartlam, M. (deposition date: 2020-09-24, release date: 2021-10-06, Last modification date: 2023-11-29)

Primary citation

Chen, Y.,Jia, H.,Zhang, J.,Liang, Y.,Liu, R.,Zhang, Q.,Bartlam, M.
Structure and mechanism of the gamma-glutamyl-gamma-aminobutyrate hydrolase SpuA from Pseudomonas aeruginosa.
Acta Crystallogr D Struct Biol, 77:1305-1316, 2021

PubMed Abstract: Polyamines are important regulators in all living organisms and are implicated in essential biological processes including cell growth, differentiation and apoptosis. Pseudomonas aeruginosa possesses an spuABCDEFGHI gene cluster that is involved in the metabolism and uptake of two polyamines: spermidine and putrescine. In the proposed γ-glutamylation-putrescine metabolism pathway, SpuA hydrolyzes γ-glutamyl-γ-aminobutyrate (γ-Glu-GABA) to glutamate and γ-aminobutyric acid (GABA). In this study, crystal structures of P. aeruginosa SpuA are reported, confirming it to be a member of the class I glutamine amidotransferase (GAT) family. Activity and substrate-binding assays confirm that SpuA exhibits a preference for γ-Glu-GABA as a substrate. Structures of an inactive H221N mutant were determined with bound glutamate thioester intermediate or glutamate product, thus delineating the active site and substrate-binding pocket and elucidating the catalytic mechanism. The crystal structure of another bacterial member of the class I GAT family from Mycolicibacterium smegmatis (MsGATase) in complex with glutamine was determined for comparison and reveals a binding site for glutamine. Activity assays confirm that MsGATase has activity for glutamine as a substrate but not for γ-Glu-GABA. The work reported here provides a starting point for further investigation of polyamine metabolism in P. aeruginosa.

PubMed: 34605433
DOI: 10.1107/S2059798321008986

Experimental method

X-RAY DIFFRACTION (1.6 Å)