Crystal Structure of Mn2+-bound Escherichia coli L-arabinose Isomerase (ECAI) and Implications in Protein Catalytic Mechanism and Thermo-Stability

Journal Article · Mon Jan 01 00:00:00 EST 2007 · Journal of Young Investigators

OSTI ID:930523

Zhu, W; Manjasetty, B; Chance, M

The functional properties of proteins depend on their three-dimensional shapes. Protein structures can be determined by X-ray crystallography as a tool. The three-dimensional structure of the apo form of the Escherichia coli L-arabinose isomerase (ECAI) has recently been determined. ECAI is responsible for the initial stage of L-arabinose catabolism, converting arabinose into ribulose in vivo. This enzyme also plays a crucial role in catalyzing the conversion of galactose into tagatose (low calorie natural sugar) in vitro. ECAI utilizes Mn{sup 2+} for its catalytic activity. Crystals of the ECAI + Mn{sup 2+} complex helps to investigate the catalytic properties of the enzyme. Therefore, crystals of ECAI + Mn{sup 2+} complex were grown using hanging drop vapor diffusion method at room temperature. Diffraction data were collected at X4C beamline, National Synchrotron Light Source, Brookhaven National Laboratory. The structure was solved by the molecular replacement technique and has been refined to Rwork of 0.23 at 2.8 {angstrom} resolution using X3A beamline computational facility. The structure was deposited to Protein Data Bank (PDB ID 2HXG). Mn{sup 2+} ion was localized to the previously identified putative active site with octahedral coordination. Comparison of apo and holo form of ECAI structures permits the identification of structural features that are of importance to the intrinsic activity and heat stability of AI.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 930523
• Report Number(s): BNL-80530-2008-JA; TRN: US0901406
• Journal Information: Journal of Young Investigators, Vol. 17, Issue 3; ISSN 1470-8175
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
43 PARTICLE ACCELERATORS
ARABINOSE
BNL
CATABOLISM
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
DIFFRACTION
DIFFUSION
ENZYMES
ESCHERICHIA COLI
FUNCTIONALS
GALACTOSE
IN VITRO
IN VIVO
ISOMERASES
NSLS
PROTEIN STRUCTURE
PROTEINS
RESOLUTION
RIBULOSE
SACCHAROSE
SENSITIVITY
THERMAL DEGRADATION
national synchrotron light source