research papers
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.
Supporting information
Portable Document Format (PDF) file https://doi.org/10.1107/S1399004714023414/qh5016sup1.pdf |
PDB references: P. furiosus L-asparaginase, wild type, 4q0m; conjoined, apo, 4ra6; complex with L-aspartic acid, 4nje; complex with citrate, 4ra9