Loading
PDBj
MenuPDBj@FacebookPDBj@X(formerly Twitter)PDBj@BlueSkyPDBj@YouTubewwPDB FoundationwwPDB
RCSB PDBPDBeBMRBAdv. SearchSearch help

2P2N

Crystal Structure and Allosteric Regulation of the Cytoplasmic Escherichia coli L-Asparaginase I

Summary for 2P2N
Entry DOI10.2210/pdb2p2n/pdb
Related2HIM 2P2D
DescriptorL-ASPARAGINASE I, CHLORIDE ION, ASPARTIC ACID, ... (6 entities in total)
Functional Keywordsasparaginase, transferase
Biological sourceEscherichia coli
Cellular locationCytoplasm: P0A962
Total number of polymer chains4
Total formula weight159817.83
Authors
Yun, M.-K.,Nourse, A.,White, S.W.,Rock, C.O.,Heath, R.J. (deposition date: 2007-03-07, release date: 2007-05-15, Last modification date: 2011-07-13)
Primary citationYun, M.-K.,Nourse, A.,White, S.W.,Rock, C.O.,Heath, R.J.
Crystal Structure and Allosteric Regulation of the Cytoplasmic Escherichia colil-Asparaginase I
J.Mol.Biol., 369:794-811, 2007
Cited by
PubMed Abstract: AnsA is the cytoplasmic asparaginase from Escherichia coli involved in intracellular asparagine utilization. Analytical ultracentifugation and X-ray crystallography reveal that AnsA forms a tetrameric structure as a dimer of two intimate dimers. Kinetic analysis of the enzyme reveals that AnsA is positively cooperative, displaying a sigmoidal substrate dependence curve with an [S](0.5) of 1 mM L-asparagine and a Hill coefficient (n(H)) of 2.6. Binding of L-asparagine to an allosteric site was observed in the crystal structure concomitant with a reorganization of the quarternary structure, relative to the apo enzyme. The carboxyl group of the bound asparagine makes salt bridges and hydrogen bonds to Arg240, while the N(delta2) nitrogen interacts with Thr162. Mutation of Arg240 to Ala increases the [S](0.5) value to 5.9 mM, presumably by reducing the affinity of the site for L-asparagine, although the enzyme retains cooperativity. Mutation of Thr162 to Ala results in an active enzyme with no cooperativity. Transmission of the signal from the allosteric site to the active site appears to involve subtle interactions at the dimer-dimer interface and relocation of Gln118 into the vicinity of the active site to position the probable catalytic water molecule. These data define the structural basis for the cooperative regulation of the intracellular asparaginase that is required for proper functioning within the cell.
PubMed: 17451745
DOI: 10.1016/j.jmb.2007.03.061
PDB entries with the same primary citation
Experimental method
X-RAY DIFFRACTION (1.9 Å)
Structure validation

227344

PDB entries from 2024-11-13

PDB statisticsPDBj update infoContact PDBjnumon