3VA7

Crystal structure of the Kluyveromyces lactis Urea Carboxylase

Summary for 3VA7

• Entry DOI: 10.2210/pdb3va7/pdb
• Descriptor: KLLA0E08119p, 5-(HEXAHYDRO-2-OXO-1H-THIENO[3,4-D]IMIDAZOL-6-YL)PENTANAL, UREA, ... (6 entities in total)
• Functional Keywords: carboxylase, ligase
• Biological source: Kluyveromyces lactis (Yeast)
• Total number of polymer chains: 1
• Total formula weight: 137903.95

Authors

Fan, C.,Xiang, S. (deposition date: 2011-12-29, release date: 2012-02-01, Last modification date: 2013-07-17)

Primary citation

Fan, C.,Chou, C.Y.,Tong, L.,Xiang, S.
Crystal structure of urea carboxylase provides insights into the carboxyltransfer reaction
J.Biol.Chem., 287:9389-9398, 2012

PubMed Abstract: Urea carboxylase (UC) is conserved in many bacteria, algae, and fungi and catalyzes the conversion of urea to allophanate, an essential step in the utilization of urea as a nitrogen source in these organisms. UC belongs to the biotin-dependent carboxylase superfamily and shares the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) domains with these other enzymes, but its carboxyltransferase (CT) domain is distinct. Currently, there is no information on the molecular basis of catalysis by UC. We report here the crystal structure of the Kluyveromyces lactis UC and biochemical studies to assess the structural information. Structural and sequence analyses indicate the CT domain of UC belongs to a large family of proteins with diverse functions, including the Bacillus subtilis KipA-KipI complex, which has important functions in sporulation regulation. A structure of the KipA-KipI complex is not currently available, and our structure provides a framework to understand the function of this complex. Most interestingly, in the structure the CT domain interacts with the BCCP domain, with biotin and a urea molecule bound at its active site. This structural information and our follow-up biochemical experiments provided molecular insights into the UC carboxyltransfer reaction. Several structural elements important for the UC carboxyltransfer reaction are found in other biotin-dependent carboxylases and might be conserved within this family, and our data could shed light on the mechanism of catalysis of these enzymes.

PubMed: 22277658
DOI: 10.1074/jbc.M111.319475

Experimental method

X-RAY DIFFRACTION (2.6 Å)