A multi-iron enzyme installs copper-binding oxazolone/thioamide pairs on a nontypeable virulence factor.

The multinuclear nonheme iron-dependent oxidases (MNIOs) are a rapidly growing family of enzymes involved in the biosynthesis of ribosomally synthesized, posttranslationally modified peptide natural products (RiPPs). Recently, a secreted virulence factor from nontypeable (NTHi) was found to be expressed from an operon, which we designate the operon, that also encodes an MNIO. Here, we show by Mössbauer spectroscopy that the MNIO HvfB contains a triiron cofactor.

Enhancing ferryl accumulation in HO-dependent cytochrome P450s.

A facile strategy is presented to enhance the accumulation of ferryl (iron(IV)-oxo) species in HO dependent cytochrome P450s (CYPs) of the CYP152 family. We report the characterization of a highly chemoselective CYP decarboxylase from Staphylococcus aureus (OleT) that is soluble at high concentrations. Examination of OleT Compound I (CpdI) accumulation with a variety of fatty acid substrates reveals a dependence on resting spin-state equilibrium.

Excision of a Protein-Derived Amine for -Aminobenzoate Assembly by the Self-Sacrificial Heterobimetallic Protein CADD.

Chlamydia protein associating with death domains (CADD), the founding member of a recently discovered class of nonheme dimetal enzymes termed hemeoxygenase-like dimetaloxidases (HDOs), plays an indispensable role in pathogen survival. CADD orchestrates the biosynthesis of -aminobenzoic acid (ABA) for integration into folate via the self-sacrificial excision of a protein-derived tyrosine (Tyr27) and several additional processing steps, the nature and timing of which have yet to be fully clarified. Nuclear magnetic resonance (NMR) and proteomics approaches reveal the source and probable timing of amine installation by a neighboring lysine (Lys152).

Self-sacrificial tyrosine cleavage by an Fe:Mn oxygenase for the biosynthesis of -aminobenzoate in .

Chlamydia protein associating with death domains (CADD) is involved in the biosynthesis of -aminobenzoate (pABA), an essential component of the folate cofactor that is required for the survival and proliferation of the human pathogen . The pathway used by for pABA synthesis differs from the canonical multi-enzyme pathway used by most bacteria that relies on chorismate as a metabolic precursor. Rather, recent work showed pABA formation by CADD derives from l-tyrosine.

Experimental and Theoretical Examination of the Kinetic Isotope Effect in Cytochrome P450 Decarboxylase OleT.

Using a combination of experimental studies, theory, simulation, and modeling, we investigate the hydrogen atom transfer (HAT) reaction by the high-valent ferryl cytochrome P450 (CYP) intermediate known as Compound I, a species that is central to innumerable and important detoxification and biosynthetic reactions. The P450 decarboxylase known as OleT converts fatty acids, a sustainable biological feedstock, into terminal alkenes and thus is of high interest as a potential means to produce fungible biofuels. Previous experimental work has established the intermediacy of Compound I in the C─C scission reaction catalyzed by OleT and an unprecedented ability to monitor the HAT process in the presence of bound fatty acid substrates.

Modeling the Ligand Effect on the Structure of CYP 450 Within the Density Functional Theory.

An improved understanding of the P450 structure is relevant to the development of biomimetic catalysts and inhibitors for controlled CH-bond activation, an outstanding challenge of synthetic chemistry. Motivated by the experimental findings of an unusually short Fe-S bond of 2.18 Å for the wild-type (WT) OleT P450 decarboxylase relative to a cysteine pocket mutant form (A369P), a computational model that captures the effect of the thiolate axial ligand on the iron-sulfur distance is presented.

Stimuli-Modulated Metal Oxidation States in Photochromic MOFs.

Tuning metal oxidation states in metal-organic framework (MOF) nodes by switching between two discrete linker photoisomers via an external stimulus was probed for the first time. On the examples of three novel photochromic copper-based frameworks, we demonstrated the capability of switching between +2 and +1 oxidation states, on demand. In addition to crystallographic methods used for material characterization, the role of the photochromic moieties for tuning the oxidation state was probed via conductivity measurements, cyclic voltammetry, and electron paramagnetic resonance, X-ray photoelectron, and diffuse reflectance spectroscopies.

BesC Initiates C-C Cleavage through a Substrate-Triggered and Reactive Diferric-Peroxo Intermediate.

BesC catalyzes the iron- and O-dependent cleavage of 4-chloro-l-lysine to form 4-chloro-l-allylglycine, formaldehyde, and ammonia. This process is a critical step for a biosynthetic pathway that generates a terminal alkyne amino acid which can be leveraged as a useful bio-orthogonal handle for protein labeling. As a member of an emerging family of diiron enzymes that are typified by their heme oxygenase-like fold and a very similar set of coordinating ligands, recently termed HDOs, BesC performs an unusual type of carbon-carbon cleavage reaction that is a significant departure from reactions catalyzed by canonical dinuclear-iron enzymes.

Direct Identification of Mixed-Metal Centers in Metal-Organic Frameworks: Cu(BTC) Transmetalated with Rh Ions.

Raman spectroscopy was used to establish direct evidence of heterometallic metal centers in a metal-organic framework (MOF). The Cu(BTC) MOF HKUST-1 (BTC = benzenetricarboxylate) was transmetalated by heating it in a solution of RhCl to substitute Rh ions for Cu ions in the dinuclear paddlewheel nodes of the framework. In addition to the Cu-Cu and Rh-Rh stretching modes, Raman spectra of (CuRh)(BTC) show the Cu-Rh stretching mode, indicating that mixed-metal Cu-Rh nodes are formed after transmetalation.

Enhanced P450 fatty acid decarboxylase catalysis by glucose oxidase coupling and co-assembly for biofuel generation.

Cytochrome P450 OleT is a fatty acid decarboxylase that uses hydrogen peroxide (HO) to catalyze the production of terminal alkenes, which are industrially important chemicals with biofuel and synthetic applications. Despite its requirement for large turnover levels, high concentrations of HO may cause heme group degradation, diminishing enzymatic activity and limiting broad application for synthesis. Here, we report an artificial enzyme cascade composed of glucose oxidase (GOx) and OleT from Staphylococcus aureus for efficient terminal alkene production.

Oxidative Decarboxylase UndA Utilizes a Dinuclear Iron Cofactor.

UndA is a nonheme iron enzyme that activates oxygen to catalyze the decarboxylation of dodecanoic acid to undecene and carbon dioxide. We report the first optical and Mössbauer spectroscopic characterization of UndA, revealing that the enzyme harbors a coupled dinuclear iron cluster. Single turnover studies confirm that the reaction of the diferrous enzyme with dioxygen produces stoichiometric product per cluster.

Divergent mechanisms of iron-containing enzymes for hydrocarbon biosynthesis.

Increasing levels of energy consumption, dwindling resources, and environmental considerations have served as compelling motivations to explore renewable alternatives to petroleum-based fuels, including enzymatic routes for hydrocarbon synthesis. Phylogenetically diverse species have long been recognized to produce hydrocarbons, but many of the enzymes responsible have been identified within the past decade. The enzymatic conversion of C chain length fatty aldehydes (or acids) to C hydrocarbons, alkanes or alkenes, involves a C-C scission reaction.

Dissecting ITC data of metal ions binding to ligands and proteins.

Background: ITC is a powerful technique that can reliably assess the thermodynamic underpinnings of a wide range of binding events. When metal ions are involved, complications arise in evaluating the data due to unavoidable solution chemistry that includes metal speciation and a variety of linked equilibria.

Scope Of Review: This paper identifies these concerns, provides recommendations to avoid common mistakes, and guides the reader through the mathematical treatment of ITC data to arrive at a set of thermodynamic state functions that describe identical chemical events and, ideally, are independent of solution conditions.