Structure of Rhizobium sp. 4-9 histamine dehydrogenase and analysis of the electron transfer pathway to an abiological electron acceptor.

Histamine dehydrogenase from the gram-negative bacterium Rhizobium sp. 4-9 (HaDHR) is a member of a small family of dehydrogenases containing a covalently attached FMN, and the only member so far identified to date that does not exhibit substrate inhibition. In this study, we present the 2.

Improving the kinetic parameters of nicotine oxidizing enzymes by homologous structure comparison and rational design.

Demand exists for a nicotine oxidase enzyme with high catalytic efficiency for a variety of applications including the in vivo detection of nicotine, therapeutic enzymatic blockade of nicotine from the CNS, and inactivation of toxic industrial wastes generated in the manufacture of tobacco products. Nicotine oxidase enzymes identified to date suffer from low efficiency, exhibiting either a high k or low K, but not both. Here we present the crystal structure of the (S)-6-hydroxy-nicotine oxidase from Shinella sp HZN7 (NctB), an enzyme that oxidizes (S)-nicotine with a high k (>1 s), that possesses remarkable structural and sequence similarity to an enzyme with a nanomolar K for (S)-nicotine, the (S)-nicotine oxidase from Pseudomonas putidia strain S16 (NicA2).

Probing Selective Self-Assembly of Putrescine Oxidase with Controlled Orientation Using a Genetically Engineered Peptide Tag.

Controlling enzyme orientation and location on surfaces is a critical step for their successful deployment in diverse applications from biosensors to lab-on-a-chip devices. Functional activity of the enzymes on the surface will largely depend on the spatial arrangement and orientation. Solid binding peptides have been proven to offer versatility for immobilization of biomolecules on inorganic materials including metals, oxides, and minerals.

Self-Immobilized Putrescine Oxidase Biocatalyst System Engineered with a Metal Binding Peptide.

Flavin oxidases are valuable biocatalysts for the oxidative synthesis of a wide range of compounds, while at the same time reduce oxygen to hydrogen peroxide. Compared to other redox enzymes, their ability to use molecular oxygen as an electron acceptor offers a relatively simple system that does not require a dissociable coenzyme. As such, they are attractive targets for adaptation as cost-effective biosensor elements.

An active site mutation in 6-hydroxy-l-Nicotine oxidase from Arthrobacter nicotinovorans changes the substrate specificity in favor of (S)-nicotine.

The enzyme 6-Hydroxy-l-Nicotine oxidase (HLNO) is a flavin-dependent enzyme that catalyzes the first step in the pyridine pathway of oxidation of nicotine as a source of energy and nitrogen in several bacteria. Recombinant Arthrobacter nicotinovorans HLNO also catalyzes oxidation of (s)-nicotine at a low but measurable rate (Fitzpatrick et al., 2016, Biochemistry 55, 697-703).

Methionine sulfoxide reductase A (MsrA) mediates the ubiquitination of 14-3-3 protein isotypes in brain.

The methionine sulfoxide reductase (Msr) system is known for its function in reducing protein-methionine sulfoxide to methionine. Recently, we showed that one member of the Msr system, MsrA, is involved in the ubiquitination-like process in Archaea. Here, the mammalian MsrA is demonstrated to mediate the ubiquitination of the 14-3-3 zeta protein and to promote the binding of 14-3-3 proteins to alpha synuclein in brain.

Retraction: X. Ma et al. Hybrid Endovascular Repair in Aortic Arch Pathologies: A Retrospective Study. Int. J. Mol. Sci. 2010, 11, 4687-4696.

We have been made aware that the figures and experimental data reported in the title paper [1] are duplicated in another publication by P. Bergeron [2]. [.

Isolated RING2 domain of parkin is sufficient for E2-dependent E3 ligase activity.

The E3 ubiquitin ligase activity of the parkin protein is implicated in playing a protective role against neurodegenerative disorders including Parkinson's, Huntington's, and Alzheimer's diseases. Parkin has four zinc-containing domains: RING0, RING1, IBR (in-between ring), and RING2. Mutational analysis of full-length parkin suggests that the C-terminal RING2 domain contains the catalytic core.

Reactive oxygen species affect ATP hydrolysis by targeting a highly conserved amino acid cluster in the thylakoid ATP synthase γ subunit.

The vast majority of organisms produce ATP by a membrane-bound rotating protein complex, termed F-ATP synthase. In chloroplasts, the corresponding enzyme generates ATP by using a transmembrane proton gradient generated during photosynthesis, a process releasing high amounts of molecular oxygen as a natural byproduct. Due to its chemical properties, oxygen can be reduced incompletely which generates several highly reactive oxygen species (ROS) that are able to oxidize a broad range of biomolecules.

The role of specific beta-gamma subunit interactions in oxyanion stimulation of the MgATP hydrolysis of a hybrid photosynthetic F1-ATPase.

Pairs of cysteine residues were introduced into the twisted N- and C-terminal helices of the gamma subunit of the chloroplast F1-ATPase to test, via disulfide cross-linking, potential inter-helical movements involved in catalysis of ATP hydrolysis. The extent of disulfide cross-linking was determined by estimating the amount of free sulfhydryl available for labeling with fluoresceinyl maleimide before and after cross-linking. Significant disulfide formation (50-75%) was observed between cysteines introduced at positions 30 and 31 in the N-terminal helix and 276 and 278 in the C-terminal helix.

C-Terminal mutations in the chloroplast ATP synthase gamma subunit impair ATP synthesis and stimulate ATP hydrolysis.

Two highly conserved amino acid residues, an arginine and a glutamine, located near the C-terminal end of the gamma subunit, form a "catch" by hydrogen bonding with residues in an anionic loop on one of the three catalytic beta subunits of the bovine mitochondrial F1-ATPase [Abrahams, J. P., Leslie, A.

Mutations within the C-terminus of the gamma subunit of the photosynthetic F1-ATPase activate MgATP hydrolysis and attenuate the stimulatory oxyanion effect.

Two highly conserved amino acid residues near the C-terminus within the gamma subunit of the mitochondrial ATP synthase form a "catch" with an anionic loop on one of the three beta subunits within the catalytic alphabeta hexamer of the F1 segment [Abrahams, J. P., Leslie, A.

Structural analysis of the regulatory dithiol-containing domain of the chloroplast ATP synthase gamma subunit.

The gamma subunit of the F1 portion of the chloroplast ATP synthase contains a critically placed dithiol that provides a redox switch converting the enzyme from a latent to an active ATPase. The switch prevents depletion of intracellular ATP pools in the dark when photophosphorylation is inactive. The dithiol is located in a special regulatory segment of about 40 amino acids that is absent from the gamma subunits of the eubacterial and mitochondrial enzymes.

Ectoadenylate kinase and plasma membrane ATP synthase activities of human vascular endothelial cells.

Formation of ATP from ADP on the external surface of vascular endothelial cells has been attributed to plasma membrane ATP synthase, ectoadenylate kinase (ecto-AK), and/or ectonucleoside diphosphokinase. These enzymes or their catalytic products have been causatively linked to the elaboration of vascular networks and the regulation of capillary function. The amount of ATP generated extracellularly is small, requiring sensitive analytical methods for quantification.

Coupling proton movement to ATP synthesis in the chloroplast ATP synthase.

The chloroplast F(0)F(1)-ATP synthase-ATPase is a tiny rotary motor responsible for coupling ATP synthesis and hydrolysis to the light-driven electrochemical proton gradient. Reversible oxidation/reduction of a dithiol, located within a special regulatory domain of the gamma subunit of the chloroplast F(1) enzyme, switches the enzyme between an inactive and an active state. This regulatory mechanism is unique to the ATP synthases of higher plants and its physiological significance lies in preventing nonproductive depletion of essential ATP pools in the dark.

Gamma-epsilon Interactions Regulate the Chloroplast ATP Synthase.

Current literature on the structure and function of the chloroplast ATP synthase is reviewed with an emphasis on the roles of the gamma and epsilon subunits. Together these two subunits are thought to couple, via rotation, the proton motive force to nucleotide synthesis and hydrolysis by the catalytic F(1) segment of the enzyme. These two subunits are also responsible for inducing the latent state of the enzyme that is necessary to prevent futile hydrolysis of ATP in the dark when electron transfer and ATP synthesis are inactive.

Observation of calcium-dependent unidirectional rotational motion in recombinant photosynthetic F1-ATPase molecules.

ATP hydrolysis and synthesis by the F(0)F(1)-ATP synthase are coupled to proton translocation across the membrane in the presence of magnesium. Calcium is known, however, to disrupt this coupling in the photosynthetic enzyme in a unique way: it does not support ATP synthesis, and CaATP hydrolysis is decoupled from any proton translocation, but the membrane does not become leaky to protons. Understanding the molecular basis of these calcium-dependent effects can shed light on the as yet unclear mechanism of coupling between proton transport and rotational catalysis.