Dynamic metal coordination controls chemoselectivity in radical halogenases.

The activation of inert C( )-H bonds by non-heme Fe enzymes plays a key role in metabolism, epigenetics, and signaling, while providing a powerful biocatalytic platform for the chemical synthesis of molecules with increased complexity. In this context, Fe /α-ketoglutarate-dependent radical halogenases represent a broadly interesting system, as they are uniquely capable of carrying out transfer of a diverse array of bound anions following C-H activation. Here, we provide the first experimental evidence that bifurcation of H-atom abstraction and radical rebound is driven both by the ability of a dynamic metal coordination sphere to reorganize as well as by a second-sphere hydrogen-bond network where only two residues (Asn224 and Ile151) are necessary and sufficient.

The nitrogen-fixing symbiosis requires CbrA-dependent regulation of a DivL and CckA phosphorelay.

The cell cycle is a fundamental process involved in bacterial reproduction and cellular differentiation. For , cell cycle outcomes depend on its growth environment. This bacterium shows a tight coupling of DNA replication initiation with cell division during free-living growth.

Expanding chemistry through in vitro and in vivo biocatalysis.

Living systems contain a vast network of metabolic reactions, providing a wealth of enzymes and cells as potential biocatalysts for chemical processes. The properties of protein and cell biocatalysts-high selectivity, the ability to control reaction sequence and operation in environmentally benign conditions-offer approaches to produce molecules at high efficiency while lowering the cost and environmental impact of industrial chemistry. Furthermore, biocatalysis offers the opportunity to generate chemical structures and functions that may be inaccessible to chemical synthesis.

Biocatalytic control of site-selectivity and chain length-selectivity in radical amino acid halogenases.

Biocatalytic C-H activation has the potential to merge enzymatic and synthetic strategies for bond formation. Fe/αKG-dependent halogenases are particularly distinguished for their ability both to control selective C-H activation as well as to direct group transfer of a bound anion along a reaction axis separate from oxygen rebound, enabling the development of new transformations. In this context, we elucidate the basis for the selectivity of enzymes that perform selective halogenation to yield 4-Cl-lysine (BesD), 5-Cl-lysine (HalB), and 4-Cl-ornithine (HalD), allowing us to probe how site-selectivity and chain length selectivity are achieved.

Reaction pathway engineering converts a radical hydroxylase into a halogenase.

Fe/α-ketoglutarate (Fe/αKG)-dependent enzymes offer a promising biocatalytic platform for halogenation chemistry owing to their ability to functionalize unactivated C-H bonds. However, relatively few radical halogenases have been identified to date, limiting their synthetic utility. Here, we report a strategy to expand the palette of enzymatic halogenation by engineering a reaction pathway rather than substrate selectivity.