Crystal Structure of the Hexamerization Domain of N-ethylmaleimide–Sensitive Fusion Protein

Abstract

N-ethylmaleimide-sensitive fusion protein (NSF) is a cytosolic ATPase required for many intracellular vesicle fusion reactions. NSF consists of an amino-terminal region that interacts with other components of the vesicle trafficking machinery, followed by two homologous ATP-binding cassettes, designated D1 and D2, that possess essential ATPase and hexamerization activities, respectively. The crystal structure of D2 bound to Mg2+-AMPPNP has been determined at 1.75 A resolution. The structure consists of a nucleotide-binding and a helical domain, and it is unexpectedly similar to the first two domains of the clamp-loading subunit delta' of E. coli DNA polymerase III. The structure suggests several regions responsible for coupling of ATP hydrolysis to structural changes in full-length NSF.

Structural similarity between the flagellar type III ATPase FliI and F 1 -ATPase subunits

“…However, they do not show any similarity in their N-terminal domains; instead, AAA ATPases have their unique domain or subdomain that follows the ATPase domain, contributing to the hexamer formation as well as the ATPase domain (30)(31)(32). Thus, the fold and the way the subunits assemble into hexamer are completely different from that of F 1 -ATPase and our FliI model.…”

Amino Acid Substitutions in the C-terminal AAA+ Module of Hsp104 Prevent Substrate Recognition by Disrupting Oligomerization and Cause High Temperature Inactivation

“…The crystal structures of the Hsp100 family members, HslU (8 -11), ClpA (12), ClpB (13), and ClpX (14) as well as the AAA ϩ modules of more distantly related AAA ϩ family members NSF (15,16) and p97 (17) clearly demonstrate that AAA ϩ proteins have conserved tertiary structures. The AAA ϩ module consists of two domains.…”

Out-of-plane motions in open sliding clamps: Molecular dynamics simulations of eukaryotic and archaeal proliferating cell nuclear antigen

“…Clamp loaders are AAA ϩ ATPases (23), and the ATP-loaded forms of many other AAA ϩ ATPases, such as N-ethylamidesensitive fusion protein (NSF), are flat, circular structures that are similar in overall shape and dimensions to PCNA (24,25). It is natural to wonder whether the clamp loader complex flattens out into an NSF-like structure to fully engage the PCNA clamp.…”