Key result
The guanine-nucleotide exchange factor RCC1 facilitates tight binding between the encephalomyocarditis virus Leader protein and cellular Ran GTPase with a KD of ~13 nM, relieving nucleotide inhibition.
The guanine-nucleotide exchange factor RCC1 facilitates exceptionally tight binding between the encephalomyocarditis virus leader protein and cellular Ran GTPase, overcoming inhibition by cellular nucleotides.
The leader (L) protein of encephalomyocarditis virus (EMCV) shuts off host cell nucleocytoplasmic trafficking (NCT) by inducing hyperphosphorylation of nuclear pore proteins. This dramatic effect by a nonenzymatic protein of 6 kDa is not well understood but clearly involves L binding to cellular Ran GTPase, a critical factor of active NCT. Exogenous GDP and GTP are inhibitory to L-Ran binding, but the guanine-nucleotide exchange factor RCC1 can relieve this inhibition. In the presence of RCC1, L binds Ran with a KD (equilibrium dissociation constant) of ≈ 3 nM and reaches saturation within 20 min. The results of fluorescently tagged nucleotide experiments suggest that L-Ran interactions affect the nucleotide-binding pocket of Ran.
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Petty et al. (2013) studied Encephalomyocarditis virus (EMCV) infection. Guanine-Nucleotide Exchange Factor RCC1 vs. Absence of RCC1 was evaluated on Equilibrium dissociation constant (KD) of L-Ran binding. The guanine-nucleotide exchange factor RCC1 facilitates tight binding between the encephalomyocarditis virus Leader protein and cellular Ran GTPase with a KD of ~13 nM, relieving nucleotide inhibition.
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