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Structure and Activity of PA5508, a Novel Hexameric Glutamine Synthase Homolog



Jane E. Ladner, James F. Parsons


The structure of PA5508 from Pseudomonas aeruginosa, a glutamine synthase (GS) homolog, has been solved 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. Other unique aspects of the structure illustrate how the enzyme is able to catalyze reactions involving bulky amines rather than ammonia. PA5508 displays no GS activity but instead acts on a variety of linear, cyclic, and aromatic mono- and polyamines.


glutamine synthase homolog, polyamine, Pseudomonas


Ladner, J. and Parsons, J. (2012), Structure and Activity of PA5508, a Novel Hexameric Glutamine Synthase Homolog, Biochemistry, [online], (Accessed March 1, 2024)
Created December 12, 2012, Updated November 10, 2018