Mapping the interaction forces between TAR RNA and TAT peptides on GaAs surfaces using chemical force microscopy.

The complexation of the HIV transactivation response element (TAR) RNA with the viral regulatory protein TAT is of enormous interest for the design of new sensing and therapeutic strategies. In this work, we anchored TAT peptides on GaAs surfaces using microcontact printing. Atomic force microscopy was used to quantify the interaction between TAR RNA and model TAT peptide sequences. Different pH conditions were utilized in order to assess specific vs nonspecific interactions. AFM tips functionalized with TAR RNA molecules were used to collect adhesion maps that displayed stronger interaction with peptide sequences that contained a greater number of arginine residues. All of the studies consistently showed a pH dependence of the interaction between the surface bound peptides and the TAR RNA on the AFM tips. This work quantifies the TAR RNA/TAT peptide interaction after one of the molecules is anchored on a surface. The conclusions in this paper are consistent with previous work and demonstrate that cationic residues are responsible for the polyelectrolyte-like affinity of TAT peptides for TAR RNA.