Abstract
Human myxovirus resistance protein 1 (MxA) restricts a wide range of viruses and is closely related to the membrane-remodelling GTPase dynamin. The functions of MxA rely on domain rearrangements coupled with GTP hydrolysis cycles. To gain insight into this process, we studied real-time domain dynamics of MxA by single-molecule fluorescence resonance energy transfer. We find that the GTPase domain-bundle-signalling-element (BSE) region can adopt either an ‘open’ or a ‘closed’ conformation in all nucleotide-loading conditions. Whereas the open conformation is preferred in nucleotide-free, GDP·AlF4−-bound and GDP-bound forms, loading of GTP activates the relative movement between the two domains and alters the conformational preference to the ‘closed’ state. Moreover, frequent relative movement was observed between BSE and stalk via hinge 1. On the basis of these results, we suggest how MxA molecules within a helical polymer collectively generate a stable torque through random GTP hydrolysis cycles. Our study provides mechanistic insights into fundamental cellular events such as viral resistance and endocytosis.
Highlights
Human myxovirus resistance protein 1 (MxA) restricts a wide range of viruses and is closely related to the membrane-remodelling GTPase dynamin
Structural studies on stalkless-MxA and the GTPase domain (GD)-BSE construct of dynamin revealed that GTP binding and a hydrolysis are coupled with relative movement between GD and BSE28–30
The MxAMO1 structure indicates that disruption of the oligomerization interfaces of the stalk does not affect the architecture of MxA
Summary
Human myxovirus resistance protein 1 (MxA) restricts a wide range of viruses and is closely related to the membrane-remodelling GTPase dynamin. Both dynamin and MxA are able to tubulate liposomes in vitro[18,23,24] They have similar architectures featured by the N-terminal GTPase domain (GD), a bundle-signallingelement (BSE) composed of three helices from widely dispersed sequence regions, and a four-helical stalk that is connected to the BSE via two loops named hinge 1 (refs 17,25–27). Their functions depend on self-assembly into polymeric rings or helical filaments via stalk, and association between the GDs from neighbouring rings/rungs[17,23,25,26,27,28]. The relative movement between BSE and stalk has not been investigated and whether this plays a role in regulating disassembly of the polymer is not understood
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have