Figure 2. NMR chemical-shift analysis of the Alba1 interaction with nucleic acids.

The weighted sum of ¹⁵N-^r and ¹H- proton chemical shift changes (√[(Δδn/10)²+Δδnh²]) upon titration of Alba with (A) 16 bp dsDNA, (B) 16 mer ssDNA, (C) 16 mer ssRNA and (D) 28A ssRNA are plotted against residue number. Vertical broken lines show residues associated with a conserved crystallographic dimer–dimer interface. Those residues with a sum chemical-shift change >0.015 are plotted. These are highlighted in red on the corresponding surface representations of Alba1 in order to indicate the regions that are perturbed upon binding. Lys¹⁶ and Arg⁴⁴, which are in intermediate exchange, are shown in dash grey. Lys¹⁶ has been shown previously to be involved in binding DNA [7], and Arg⁴⁴ is likely to be involved given its position and charge. The structural representations were generated using MacPyMOL (DeLano Scientific; http://www.pymol.org).