3M4J

Crystal structure of N-acetyl-L-ornithine transcarbamylase complexed with PALAO

Summary for 3M4J

• Entry DOI: 10.2210/pdb3m4j/pdb
• Related: 3KZK 3KZO
• Descriptor: N-acetylornithine carbamoyltransferase, N~2~-acetyl-N~5~-(phosphonoacetyl)-L-ornithine, SULFATE ION, ... (4 entities in total)
• Functional Keywords: transcarbamylase, transferase
• Biological source: Xanthomonas campestris pv. campestris
• Cellular location: Cytoplasm : Q8P8J2
• Total number of polymer chains: 1
• Total formula weight: 40525.85

Authors

Li, Y.,Yu, X.,Allewell, N.M.,Tuchman, M.,Shi, D. (deposition date: 2010-03-11, release date: 2010-07-28, Last modification date: 2023-11-22)

Primary citation

Li, Y.,Yu, X.,Ho, J.,Fushman, D.,Allewell, N.M.,Tuchman, M.,Shi, D.
Reversible Post-Translational Carboxylation Modulates the Enzymatic Activity of N-Acetyl-l-ornithine Transcarbamylase.
Biochemistry, 49:6887-6895, 2010

PubMed Abstract: N-Acetyl-l-ornithine transcarbamylase (AOTCase), rather than ornithine transcarbamylase (OTCase), is the essential carbamylase enzyme in the arginine biosynthesis of several plant and human pathogens. The specificity of this unique enzyme provides a potential target for controlling the spread of these pathogens. Recently, several crystal structures of AOTCase from Xanthomonas campestris (xc) have been determined. In these structures, an unexplained electron density at the tip of the Lys302 side chain was observed. Using (13)C NMR spectroscopy, we show herein that Lys302 is post-translationally carboxylated. The structure of wild-type AOTCase in a complex with the bisubstrate analogue N(delta)-(phosphonoacetyl)-N(alpha)-acetyl-l-ornithine (PALAO) indicates that the carboxyl group on Lys302 forms a strong hydrogen bonding network with surrounding active site residues, Lys252, Ser253, His293, and Glu92 from the adjacent subunit either directly or via a water molecule. Furthermore, the carboxyl group is involved in binding N-acetyl-l-ornithine via a water molecule. Activity assays with the wild-type enzyme and several mutants demonstrate that the post-translational modification of lysine 302 has an important role in catalysis.

PubMed: 20695527
DOI: 10.1021/bi1007386

Experimental method

X-RAY DIFFRACTION (2.2 Å)