Stereochemical Consequences of Vinylpyruvate Hydratase-Catalyzed Reactions.

A stereochemical analysis has been carried out on two vinylpyruvate hydratases (VPH), which convert 2-hydroxy-2,4-pentadienoate to 2-keto-4S-hydroxypentanoate in meta-fission pathways. Bacterial strains with this pathway can use aromatic compounds as sole sources of energy and carbon. The analysis was carried out using the 5-methyl and 5-chloro derivatives of 2-hydroxy-2,4-pentadienoate with the enzymes from Pseudomonas putida mt-2 (Pp) and Leptothrix cholodnii SP-6 (Lc).

Identification and characterization of new family members in the tautomerase superfamily: analysis and implications.

Tautomerase superfamily members are characterized by a β-α-β building block and a catalytic amino terminal proline. 4-Oxalocrotonate tautomerase (4-OT) and malonate semialdehyde decarboxylase (MSAD) are the title enzymes of two of the five known families in the superfamily. Two recent developments in these families indicate that there might be more metabolic diversity in the tautomerase superfamily than previously thought.

Structural and kinetic characterization of two 4-oxalocrotonate tautomerases in Methylibium petroleiphilum strain PM1.

Methylibium petroleiphilum strain PM1 uses various petroleum products including the fuel additive methyl tert-butyl ether and straight chain and aromatic hydrocarbons as sole carbon and energy sources. It has two operons, dmpI and dmpII, that code for the enzymes in a pair of parallel meta-fission pathways. In order to understand the roles of the pathways, the 4-oxalocrotonate tautomerase (4-OT) isozyme from each pathway was characterized.

Kinetic, crystallographic, and mechanistic characterization of TomN: elucidation of a function for a 4-oxalocrotonate tautomerase homologue in the tomaymycin biosynthetic pathway.

The biosynthesis of the C ring of the antitumor antibiotic agent, tomaymycin, is proposed to proceed through five enzyme-catalyzed steps from l-tyrosine. The genes encoding these enzymes have recently been cloned and their functions tentatively assigned, but there is limited biochemical evidence supporting the assignments of the last three steps. One enzyme, TomN, shows 58% pairwise sequence similarity with 4-oxalocrotonate tautomerase (4-OT), an enzyme found in a catabolic pathway for aromatic hydrocarbons.

Kinetic and structural characterization of a heterohexamer 4-oxalocrotonate tautomerase from Chloroflexus aurantiacus J-10-fl: implications for functional and structural diversity in the tautomerase superfamily .

4-Oxalocrotonate tautomerase (4-OT) isozymes play prominent roles in the bacterial utilization of aromatic hydrocarbons as sole carbon sources. These enzymes catalyze the conversion of 2-hydroxy-2,4-hexadienedioate (or 2-hydroxymuconate) to 2-oxo-3-hexenedioate, where Pro-1 functions as a general base and shuttles a proton from the 2-hydroxyl group of the substrate to the C-5 position of the product. 4-OT, a homohexamer from Pseudomonas putida mt-2, is the most extensively studied 4-OT isozyme and the founding member of the tautomerase superfamily.

Crystal structures of native and inactivated cis-3-chloroacrylic acid dehalogenase. Structural basis for substrate specificity and inactivation by (R)-oxirane-2-carboxylate.

The bacterial degradation pathways for the nematocide 1,3-dichloropropene rely on hydrolytic dehalogenation reactions catalyzed by cis- and trans-3-chloroacrylic acid dehalogenases (cis-CaaD and CaaD, respectively). X-ray crystal structures of native cis-CaaD and cis-CaaD inactivated by (R)-oxirane-2-carboxylate were elucidated. They locate four known catalytic residues (Pro-1, Arg-70, Arg-73, and Glu-114) and two previously unknown, potential catalytic residues (His-28 and Tyr-103').

Secretory leukocyte protease inhibitor: inhibition of human immunodeficiency virus-1 infection of monocytic THP-1 cells by a newly cloned protein.

The ability of the salivary protein, secretory leukocyte protease inhibitor (SLPI), to inhibit human immunodeficiency virus-1 (HIV-1) infection in vitro has been reported previously and has led to the suggestion that SLPI may be partially responsible for the low oral transmission rate of HIV-1. However, results contradictory to these findings have also been published. These discrepancies can be attributed to a number of factors ranging from the variability of macrophage susceptibility to HIV infection to the quality of commercially available preparations of SLPI.