Metalloenzymes for Fatty Acid‐Derived Hydrocarbon Biosynthesis: Nature's Cryptic Catalysts

Abstract

Waning resources, massive energy consumption, ever‐deepening global warming crisis, and climate change have raised grave concerns regarding continued dependence on fossil fuels as the predominant source of energy and generated tremendous interest for developing biofuels, which are renewable. Hydrocarbon‐based ′drop‐in′ biofuels can be a proper substitute for fossil fuels such as gasoline or jet fuel. In Nature, hydrocarbons are produced by diverse organisms such as insects, plants, bacteria, and cyanobacteria. Metalloenzymes play a crucial role in hydrocarbons biosynthesis, and the past decade has witnessed discoveries of a number of metalloenzymes catalyzing hydrocarbon biosynthesis from fatty acids and their derivatives employing unprecedented mechanisms. These discoveries elucidated the enigma related to the divergent chemistries involved in the catalytic mechanisms of these metalloenzymes. There is substantial diversity in the structure, mode of action, cofactor requirement, and substrate scope among these metalloenzymes. Detailed structural analysis along with mutational studies of some of these enzymes have contributed significantly to identifying the key amino acid residues that dictate substrate specificity and catalytic intricacy. In this Review, we discuss the metalloenzymes that catalyze fatty acid‐derived hydrocarbon biosynthesis in various organisms, emphasizing the active site architecture, catalytic mechanism, cofactor requirements, and substrate specificity of these enzymes. Understanding such details is essential for successfully implementing these enzymes in emergent biofuel research through protein engineering and synthetic biology approaches.

Unraveling the Conversion of Fatty Acids into Terminal Alkenes by an Integral Membrane Enzyme, UndB

“…Therefore, the biosynthesis of hydrocarbons in a sustainable fashion has gained tremendous attention as these molecules are the major components of fossil fuels. − There are two natural pathways leading to the biosynthesis of hydrocarbons, aldehyde decarbonylation and fatty acid decarboxylation (Figure S1). , Since fatty acids are naturally abundant, their conversion into terminal olefins has attracted enormous scientific interest. Terminal olefins are also extensively used in various industries, such as polymer, lubricant, and detergent. − …”

De-novo genome assembly of the invasive mosquito species Aedes japonicus and Aedes koreicus

“…In adults of Ae. japonicus, among the many genes up-regulated after exposure to 15°C, we should mention the members of the Cytochrome P450 and Acyl-CoA desaturase families which role in cold adaptation has already been described (37). Moreover, genes of the Actin family, that in Culex pipiens are known to be expressed from early diapause to late diapause and in young nondiapaused adult mosquitoes reared at 18°C (38), were found up-regulated, as well as members of Mitochondrial carriers and members of the Methyltransferase superfamily.…”

A chimeric membrane enzyme and an engineered whole-cell biocatalyst for efficient 1-alkene production

“…1-Alkenes are also heavily used as commodity chemicals in various industries as precursors of detergents, polymers, and lubricants (6)(7)(8)(9)(10), making them attractive molecules to biosynthesize. A feasible route to 1-alkene biosynthesis is the enzymatic one-step decarboxylation of naturally abundant free fatty acids by fatty acid decarboxylases (11,12). These enzymes include a heme-containing soluble cytochrome P450 enzyme, OleT (13); a soluble non-heme diiron enzyme, UndA (14,15); and a recently explored integral membrane enzyme, UndB (16,17).…”