4WB4

wt SA11 NSP4_CCD

Summary for 4WB4

• Entry DOI: 10.2210/pdb4wb4/pdb
• Related: 4WBA
• Descriptor: Non-structural glycoprotein NSP4, CALCIUM ION (3 entities in total)
• Functional Keywords: nonstructural protein, enterotoxin, ca2+-binding protein, viral protein
• Biological source: Simian rotavirus A/SA11
• Total number of polymer chains: 2
• Total formula weight: 12710.99

Authors

Viskovska, M.,Sastri, N.P.,Hyser, J.M.,Tanner, M.R.,Horton, L.B.,Sankaran, B.,Prasad, B.V.V.,Estes, M.K. (deposition date: 2014-09-02, release date: 2014-09-24, Last modification date: 2023-09-27)

Primary citation

Sastri, N.P.,Viskovska, M.,Hyser, J.M.,Tanner, M.R.,Horton, L.B.,Sankaran, B.,Prasad, B.V.,Estes, M.K.
Structural Plasticity of the Coiled-Coil Domain of Rotavirus NSP4.
J.Virol., 88:13602-13612, 2014

PubMed Abstract: Rotavirus (RV) nonstructural protein 4 (NSP4) is a virulence factor that disrupts cellular Ca(2+) homeostasis and plays multiple roles regulating RV replication and the pathophysiology of RV-induced diarrhea. Although its native oligomeric state is unclear, crystallographic studies of the coiled-coil domain (CCD) of NSP4 from two different strains suggest that it functions as a tetramer or a pentamer. While the CCD of simian strain SA11 NSP4 forms a tetramer that binds Ca(2+) at its core, the CCD of human strain ST3 forms a pentamer lacking the bound Ca(2+) despite the residues (E120 and Q123) that coordinate Ca(2+) binding being conserved. In these previous studies, while the tetramer crystallized at neutral pH, the pentamer crystallized at low pH, suggesting that preference for a particular oligomeric state is pH dependent and that pH could influence Ca(2+) binding. Here, we sought to examine if the CCD of NSP4 from a single RV strain can exist in two oligomeric states regulated by Ca(2+) or pH. Biochemical, biophysical, and crystallographic studies show that while the CCD of SA11 NSP4 exhibits high-affinity binding to Ca(2+) at neutral pH and forms a tetramer, it does not bind Ca(2+) at low pH and forms a pentamer, and the transition from tetramer to pentamer is reversible with pH. Mutational analysis shows that Ca(2+) binding is necessary for the tetramer formation, as an E120A mutant forms a pentamer. We propose that the structural plasticity of NSP4 regulated by pH and Ca(2+) may form a basis for its pleiotropic functions during RV replication.

PubMed: 25231315
DOI: 10.1128/JVI.02227-14

Experimental method

X-RAY DIFFRACTION (2.03 Å)