Holo Structure and Steady State Kinetics of the Thiazolinyl Imine Reductases for Siderophore Biosynthesis.
Thiazolinyl imine reductases catalyze the NADPH-dependent reduction of a thiazoline to a thiazolidine, a required step in the formation of the siderophores yersiniabactin (Yersinia spp.) and pyochelin (Pseudomonas aeruginosa). These stand-alone nonribosomal peptide tailoring domains are structural homologues of sugar oxidoreductases. Two closed structures of the thiazolinyl imine reductase from Yersinia enterocolitica (Irp3) are presented here: an NADP(+)-bound structure to 1.45 Å resolution and a holo structure to 1.28 Å resolution with NADP(+) and a substrate analogue bound. Michaelis-Menten kinetics were measured using the same substrate analogue and the homologue from P. aeruginosa, PchG. The data presented here support the hypothesis that tyrosine 128 is the likely general acid residue for catalysis and also highlight the phosphopantetheine tunnel for tethering of the substrate to the nonribosomal peptide synthetase module during assembly line biosynthesis of the siderophore.
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Kathleen M
KM
Meneely
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Trey A
TA
Ronnebaum
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Andrew P
AP
Riley
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Thomas E
TE
Prisinzano
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Audrey L
AL
Lamb
D018360:Crystallography, X-Ray; D007700:Kinetics; D013058:Mass Spectrometry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D017262:Siderophores / Q000096:biosynthesis*
D017262:Siderophores; D010088:Oxidoreductases