4PGA

GLUTAMINASE-ASPARAGINASE FROM PSEUDOMONAS 7A

Summary for 4PGA

• Entry DOI: 10.2210/pdb4pga/pdb
• Descriptor: GLUTAMINASE-ASPARAGINASE, SULFATE ION, AMMONIUM ION, ... (4 entities in total)
• Functional Keywords: bacterial amidohydrolase
• Biological source: Pseudomonas sp. 7A
• Cellular location: Periplasm: P10182
• Total number of polymer chains: 2
• Total formula weight: 72734.04

Authors

Jakob, C.G.,Lewinski, K.,Lacount, M.W.,Roberts, J.,Lebioda, L. (deposition date: 1997-01-14, release date: 1997-07-23, Last modification date: 2024-05-22)

Primary citation

Jakob, C.G.,Lewinski, K.,LaCount, M.W.,Roberts, J.,Lebioda, L.
Ion binding induces closed conformation in Pseudomonas 7A glutaminase-asparaginase (PGA): crystal structure of the PGA-SO4(2-)-NH4+ complex at 1.7 A resolution.
Biochemistry, 36:923-931, 1997

PubMed Abstract: Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D- and L-isomers of glutamine and asparagine. X-ray quality type-1 crystals of PGA have been obtained from 2.0 M ammonium sulfate. The space group is C222(1) with unit-cell dimensions a = 78.62, b = 135.80, and c = 137.88 A. The tetrameric molecule is located on a crystallographic 2-fold axis, and two subunits form the asymmetric portion of the unit cell. The structure was solved by the molecular replacement method and refined at 1.7 A resolution to an R = 19.9% with a good geometry of the model, G = 0.05. The resultant electron density maps enabled us to resolve individual constituent atoms of most residues and introduce minor revisions to the amino acid sequence. The catalytic loop, Thr20-Gly40, is in the closed conformation with excellent electron density in both subunits. A sulfate ion and an ammonium ion are bound in the substrate binding site and interect with the loop. This interaction appears to be responsible for the observed closed conformation. New arguments supporting Thr20 as the catalytic nucleophile in the asparaginase activity are proposed.

PubMed: 9020792
DOI: 10.1021/bi961979x

Experimental method

X-RAY DIFFRACTION (1.7 Å)