HXMS analysis reveals that HART substitution enhances Nef:mSH3 domain interaction without influencing mSH3 dynamics. The wild-type (WT) and HART mHck SH3 domains were exposed to deuterium in the presence or absence of Nef. Representative mass spectra showing an increase in m/z for the +6 charge state with increasing exposure time are presented for the WT mSH3 domain alone (A) and bound to Nef (B), and for mSH3-HART alone (C) and bound to Nef (D). An adduct peak (indicated by an asterisk) is also observed in each spectrum. (E) Unfolding half-lives for the SH3 domains both free and bound to Nef as well as the calculated slowdown factors (SF). The slowdown factor is a measure of the influence of Nef binding on the cooperative unfolding rate of the SH3 domain, and is calculated by taking the ratio of the unfolding half-life under different conditions as described in Hochrein, et al.  All HXMS studies were performed with Nef-Consensus.
Pene-Dumitrescu et al. BMC Chemical Biology 2012 12:1 doi:10.1186/1472-6769-12-1