Steve Ealick's Research Group

Klebsiella pneumoniae HpxJ

PDB file:



Klebsiella pneumoniae HpxJ is an aminotransferase that preferentially converts ureidoglycine and an α-keto acid into oxalurate and the corresponding amino acid. The crystal structure of KpHpxJ allowed us to present an explanation for its substrate specificity.

The KpHpxJ protomer, shown at right, shows a high degree of structural conservation with the members of the alanine-glyoxylate aminotransferase superfamily, but exhibits a relatively large degree of variation among active site residues. 


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HpxJ has a homotetramer as the biologically relevant unit.

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Since this enzyme was highly similar to other PLP-dependent aminotransferases, it was not surprising to find a covalently bound PLP molecule in the active site. Ureidoglycine was modeled into the KpHpxJ active site to maintain a reasonable proximity to PLP. 

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French JB and Ealick SE. Biochemical and Structural Characterization of a Ureidoglycine Aminotransferase in the Klebsiella Pneumoniae Ureide Catabolic Pathway. Biochemistry 49:5975-5977 (2010).

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