Publications

• Conformational changes and substrate recognition in Pseudomonas aeruginosa D-arginine dehydrogenase.

  Fu G., Yuan H., Li C., Lu C.D., Gadda G., Weber I.T.

  DADH catalyzes the flavin-dependent oxidative deamination of d-amino acids to the corresponding α-keto acids and ammonia. Here we report the first X-ray crystal structures of DADH at 1.06 Å resolution and its complexes with iminoarginine (DADH(red)/iminoarginine) and iminohistidine (DADH(red)/imin ... >> More

  DADH catalyzes the flavin-dependent oxidative deamination of d-amino acids to the corresponding α-keto acids and ammonia. Here we report the first X-ray crystal structures of DADH at 1.06 Å resolution and its complexes with iminoarginine (DADH(red)/iminoarginine) and iminohistidine (DADH(red)/iminohistidine) at 1.30 Å 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. << Less

  Biochemistry 49:8535-8545(2010) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Regulation of the dauBAR operon and characterization of D-amino acid dehydrogenase DauA in arginine and lysine catabolism of Pseudomonas aeruginosa PAO1.

  Li C., Yao X., Lu C.D.

  A unique D-to-L racemization of arginine by coupled arginine dehydrogenases DauA and DauB encoded by the dauBAR operon has been recently reported as a prerequisite for D-arginine utilization as the sole source of carbon and nitrogen through L-arginine catabolic pathways in P. aeruginosa. In this s ... >> More

  A unique D-to-L racemization of arginine by coupled arginine dehydrogenases DauA and DauB encoded by the dauBAR operon has been recently reported as a prerequisite for D-arginine utilization as the sole source of carbon and nitrogen through L-arginine catabolic pathways in P. aeruginosa. In this study, enzymic properties of the catabolic FAD-dependent d-amino acid dehydrogenase DauA and the physiological functions of the dauBAR operon were further characterized with other d-amino acids. These results establish DauA as a D-amino acid dehydrogenase of broad substrate specificity, with D-Arg and D-Lys as the two most effective substrates, based on the kinetic parameters. In addition, expression of dauBAR is specifically induced by exogenous D-Arg and D-Lys, and mutations in the dauBAR operon affect utilization of these two amino acids alone. The function of DauR as a repressor in the control of the dauBAR operon was demonstrated by dauB promoter activity measurements in vivo and mobility shift assays with purified His-tagged protein in vitro. The potential effect of 2-ketoarginine (2-KA) derived from D-Arg deamination by DauA as a signal molecule in dauBAR induction was first revealed by mutation analysis and further supported by its in vitro effect on alleviation of DauR-DNA interactions. Through sequence analysis, putative DauR operators were identified and confirmed by mutation analysis. Induction of the dauBAR operon to the maximal level was found to require the L-arginine-responsive regulator ArgR, as supported by the loss of inductive effect by L-Arg on dauBAR expression in the argR mutant and binding of purified ArgR to the dauB regulatory region in vitro. In summary, this study establishes that optimal induction of the dauBAR operon requires relief of DauR repression by 2-KA and activation of ArgR by L-Arg as a result of d-Arg racemization by the encoded DauA and DauB. << Less

  Microbiology 156:60-71(2010) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.