2IUC

Structure of alkaline phosphatase from the Antarctic bacterium TAB5

Summary for 2IUC

• Entry DOI: 10.2210/pdb2iuc/pdb
• Descriptor: ALKALINE PHOSPHATASE, ZINC ION, MAGNESIUM ION, ... (7 entities in total)
• Functional Keywords: hydrolase, alkaline phosphatase, cold adaptation, psycrophiles
• Biological source: ANTARCTIC BACTERIUM TAB5; More
• Total number of polymer chains: 2
• Total formula weight: 81197.40

Authors

Wang, E.,Koutsioulis, D.,Leiros, H.K.S.,Andersen, O.A.,Bouriotis, V.,Hough, E.,Heikinheimo, P. (deposition date: 2006-06-01, release date: 2006-11-28, Last modification date: 2023-12-13)

Primary citation

Wang, E.,Koutsioulis, D.,Leiros, H.K.S.,Andersen, O.A.,Bouriotis, V.,Hough, E.,Heikinheimo, P.
Crystal Structure of Alkaline Phosphatase from the Antarctic Bacterium Tab5.
J.Mol.Biol., 366:1318-, 2007

PubMed Abstract: Alkaline phosphatases (APs) are non-specific phosphohydrolases that are widely used in molecular biology and diagnostics. We describe the structure of the cold active alkaline phosphatase from the Antarctic bacterium TAB5 (TAP). The fold and the active site geometry are conserved with the other AP structures, where the monomer has a large central beta-sheet enclosed by alpha-helices. The dimer interface of TAP is relatively small, and only a single loop from each monomer replaces the typical crown domain. The structure also has typical cold-adapted features; lack of disulfide bridges, low number of salt-bridges, and a loose dimer interface that completely lacks charged interactions. The dimer interface is more hydrophobic than that of the Escherichia coli AP and the interactions have tendency to pair with backbone atoms, which we propose to result from the cold adaptation of TAP. The structure contains two additional magnesium ions outside of the active site, which we believe to be involved in substrate binding as well as contributing to the local stability. The M4 site stabilises an interaction that anchors the substrate-coordinating R148. The M5 metal-binding site is in a region that stabilises metal coordination in the active site. In other APs the M5 binding area is supported by extensive salt-bridge stabilisation, as well as positively charged patches around the active site. We propose that these charges, and the TAP M5 binding, influence the release of the product phosphate and thus might influence the rate-determining step of the enzyme.

PubMed: 17198711
DOI: 10.1016/J.JMB.2006.11.079

Experimental method

X-RAY DIFFRACTION (1.95 Å)