Contribution of the residue at position 4 within classical nuclear localization signals to modulating interaction with importins and nuclear targeting

Publication date: August 2018Source: Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, Volume 1865, Issue 8Author(s): Kate M. Smith, Veronica Di Antonio, Luca Bellucci, David R. Thomas, Fabiana Caporuscio, Francesco Ciccarese, Hanieh Ghassabian, Kylie M. Wagstaff, Jade K. Forwood, David A. Jans, Giorgio Palù, Gualtiero AlvisiAbstractNuclear import involves the recognition by importin (IMP) superfamily members of nuclear localization signals (NLSs) within protein cargoes destined for the nucleus, the best understood being recognition of classical NLSs (cNLSs) by the IMPα/β1 heterodimer. Although the cNLS consensus [K-(K/R)-X-(K/R) for positions P2–P5] is generally accepted, recent studies indicated that the contribution made by different residues at the P4 position can vary. Here, we apply a combination of microscopy, molecular dynamics, crystallography, in vitro binding, and bioinformatics approaches to show that the nature of residues at P4 indeed modulates cNLS function in the context of a prototypical Simian Virus 40 large tumor antigen-derived cNLS (KKRK, P2–5). Indeed, all hydrophobic substitutions in place of R impaired binding to IMPα and nuclear targeting, with the largest effect exerted by a G residue at P4. Substitution of R with neutral hydrophobic residues caused the loss of electrostatic and van der Waals interactions between the P4 residue side chains and IMPα. Detailed bioinformatics analysis confirmed the importance of the P4 residue for ...

Source: Biochimica et Biophysica Acta (BBA) Molecular Cell Research - July 11, 2018 Category: Molecular Biology Source Type: research