1ymq
From Proteopedia
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'''HAD Superfamily Phosphotransferase Substrate Diversification: Structure and Function Analysis of the HAD Subclass IIB Sugar Phosphatase BT4131''' | '''HAD Superfamily Phosphotransferase Substrate Diversification: Structure and Function Analysis of the HAD Subclass IIB Sugar Phosphatase BT4131''' | ||
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[[Category: Dunaway-Mariano, D.]] | [[Category: Dunaway-Mariano, D.]] | ||
[[Category: Lu, Z.]] | [[Category: Lu, Z.]] | ||
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| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:31:07 2008'' | |
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Revision as of 13:31, 3 May 2008
HAD Superfamily Phosphotransferase Substrate Diversification: Structure and Function Analysis of the HAD Subclass IIB Sugar Phosphatase BT4131
Overview
The BT4131 gene from the bacterium Bacteroides thetaiotaomicron VPI-5482 has been cloned and overexpressed in Escherichia coli. The protein, a member of the haloalkanoate dehalogenase superfamily (subfamily IIB), was purified to homogeneity, and its X-ray crystal structure was determined to1.9 A resolution using the molecular replacement phasing method. BT4131 was shown by an extensive substrate screen to be a broad-range sugar phosphate phosphatase. On the basis of substrate specificity and gene context, the physiological function of BT4131 in chitin metabolism has been tentatively assigned. Comparison of the BT4131 structure alpha/beta cap domain structure with those of other type IIB enzymes (phosphoglycolate phosphatase, trehalose-6-phosphate phosphatase, and proteins of unknown function known as PDB entries , , and ) identified two conserved loops (BT4131 residues 172-182 and 118-130) in the alphabetabeta(alphabetaalphabeta)alphabetabeta type caps and one conserved loop in the alphabetabetaalphabetabeta type caps, which contribute residues for contact with the substrate leaving group. In BT4131, the two loops contribute one polar and two nonpolar residues to encase the displaced sugar. This finding is consistent with the lax specificity BT4131 has for the ring size and stereochemistry of the sugar phosphate. In contrast, substrate docking showed that the high-specificity phosphoglycolate phosphatase (PDB entry ) uses a single substrate specificity loop to position three polar residues for interaction with the glycolate leaving group. We show how active site "solvent cages" derived from analysis of the structures of the type IIB HAD phosphatases could be used in conjunction with the identity of the residues stationed along the cap domain substrate specificity loops, as a means of substrate identification.
About this Structure
1YMQ is a Single protein structure of sequence from Bacteroides thetaiotaomicron. Full crystallographic information is available from OCA.
Reference
HAD superfamily phosphotransferase substrate diversification: structure and function analysis of HAD subclass IIB sugar phosphatase BT4131., Lu Z, Dunaway-Mariano D, Allen KN, Biochemistry. 2005 Jun 21;44(24):8684-96. PMID:15952775 Page seeded by OCA on Sat May 3 16:31:07 2008
