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Crystal Structure of Pseudomonas aeruginosa D-Arginine Dehydrogenase in Complex with Imino-Arginine
Structural highlights
FunctionDAUA_PSEAE DauA is highly expressed within the cystic fibrosis (CF) lung, and it is required for virulence via the optimal production of hydrogen cyanide, pyocyanine, pyoverdine, rhamnolipid and alginate during biofilm formation (PubMed:24011342). Involved in the catabolism of D-lysine and D-arginine. Under aerobic conditions, the arginine succinyltransferase (AST) and arginine transaminase (ATA) pathways are 2 major routes for L-arginine utilization as the sole source of carbon and nitrogen. The D-to-L racemization of arginine by DauA and DauB is necessary, before to be channeled into the AST and/or ATA pathways. DauA catalyzes the flavin-dependent oxidative deamination of D-arginine into 2-ketoarginine (2-KA) and ammonia (PubMed:3141581, PubMed:19139398, PubMed:19850617, PubMed:20809650). It has also dehydrogenase activity towards D-lysine, D-tyrosine, D-methionine, D-phenylalanine, D-ornithine, D-histidine and D-leucine as substrates (PubMed:19850617, PubMed:20809650).[1] [2] [3] [4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDADH catalyzes the flavin-dependent oxidative deamination of d-amino acids to the corresponding alpha-keto acids and ammonia. Here we report the first X-ray crystal structures of DADH at 1.06 A resolution and its complexes with iminoarginine (DADH(red)/iminoarginine) and iminohistidine (DADH(red)/iminohistidine) at 1.30 A resolution. The DADH crystal structure comprises an unliganded conformation and a product-bound conformation, which is almost identical to the DADH(red)/iminoarginine crystal structure. The active site of DADH was partially occupied with iminoarginine product (30% occupancy) that interacts with Tyr53 in the minor conformation of a surface loop. This flexible loop forms an "active site lid", similar to those seen in other enzymes, and may play an essential role in substrate recognition. The guanidinium side chain of iminoarginine forms a hydrogen bond interaction with the hydroxyl of Thr50 and an ionic interaction with Glu87. In the structure of DADH in complex with iminohistidine, two alternate conformations were observed for iminohistidine where the imidazole groups formed hydrogen bond interactions with the side chains of His48 and Thr50 and either Glu87 or Gln336. The different interactions and very distinct binding modes observed for iminoarginine and iminohistidine are consistent with the 1000-fold difference in k(cat)/K(m) values for d-arginine and d-histidine. Comparison of the kinetic data for the activity of DADH on different d-amino acids and the crystal structures in complex with iminoarginine and iminohistidine establishes that this enzyme is characterized by relatively broad substrate specificity, being able to oxidize positively charged and large hydrophobic d-amino acids bound within a flask-like cavity. Conformational Changes and Substrate Recognition in Pseudomonas aeruginosa d-Arginine Dehydrogenase (,).,Fu G, Yuan H, Li C, Lu CD, Gadda G, Weber IT Biochemistry. 2010 Sep 9. PMID:20809650[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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