A cage for catalysts

Abstract

Biochemistry The biosynthetic reactions that power cells often require unstable or toxic intermediates that must be contained and kept at low concentrations. One strategy to manage transient species is physical encapsulation, which can occur at many different size scales. Bernhardsgrutter et al. characterized a protein cage formed by conjoined catalytic domains, creating an incredibly small “nanoreactor” for three sequential reactions in a carbon-fixation pathway. A crystal structure revealed that each domain houses an independent active site facing the interior compartment. Enzyme kinetics suggest that the cage can close upon substrate and cofactor binding, preventing release of reaction intermediates, which have reactive moieties. Nat. Chem. Biol. 14 , 1127 (2018).