National Center for
4RA9: Crystal Structure Of Conjoint Pyrococcus Furiosus L-asparaginase With Citrate
Structural and functional insights into an archaeal L-asparaginase obtained through the linker-less assembly of constituent domains
Acta Crystallogr. D Biol. Crystallogr. (2014) 70 p.3187-3197
Covalent linkers bridging the domains of multidomain proteins are considered to be crucial for assembly and function. In this report, an exception in which the linker of a two-domain dimeric L-asparaginase from Pyrococcus furiosus (PfA) was found to be dispensable is presented. Domains of this enzyme assembled without the linker into a conjoined tetrameric form that exhibited higher activity than the parent enzyme. The global shape and quaternary structure of the conjoined PfA were also similar to the wild-type PfA, as observed by their solution scattering profiles and X-ray crystallographic data. Comparison of the crystal structures of substrate-bound and unbound enzymes revealed an altogether new active-site composition and mechanism of action. Thus, conjoined PfA is presented as a unique enzyme obtained through noncovalent, linker-less assembly of constituent domains that is stable enough to function efficiently at elevated temperatures.