title: Structure and activity of PA5508, a hexameric glutamine synthetase homologue.
abstract: The structure of PA5508 from Pseudomonas aeruginosa, a glutamine synthetase (GS) homologue, has been determined at 2.5 Å. Surprisingly, PA5508 forms single hexameric rings rather than the stacked double rings that are characteristic of GS. The C-terminal helical thong motif that links GS rings is present in PA5508; however, it is folded back toward the core of its own polypeptide, preventing it from interacting with a second ring. Interestingly, PA5508 displays a clear preference for aromatic amine substrates. Unique aspects of the structure illustrate how the enzyme is able to catalyze reactions involving bulky amines rather than ammonia.
authors.affiliation: Institute for Bioscience and Biotechnology Research, University of Maryland, MD, USA.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Ladner
authors.forename: Vesna
authors.initials: V
authors.lastname: Atanasova
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Dolezelova
authors.forename: James F
authors.initials: JF
authors.lastname: Parsons
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011073:Polyamines / Q000378:metabolism; D055503:Protein Multimerization; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D011073:Polyamines; D005974:Glutamate-Ammonia Ligase