Figure 5.

ASLV TM CR region histidine residues are important for stability at low pH. A) Left panels: ribbon diagrams of ASLV TM, HTLV‐1 gp21, IAV HA₂, and EBOV GP₂. Molecules are viewed down the 3‐fold axis with the CR region facing toward the viewer. Right panels: electrostatic potential mapped onto the molecular surface. Red and blue regions denote negative and positive charges, respectively. Positively charged residues that stabilize the negative helix dipole moment are highlighted as green sticks. B) CD thermal denaturation profiles of ASLV TM His490Ala, His490Arg, His492Ala, His492Glu, and HTLV‐1 gp21 Lys394His at pH 8.0, 7.5, 6.5, and 5.0. CD signal was normalized between 0 (folded) and 1 (unfolded).