FIG. 6.

Stabilizing interactions for the K531 loop. (A) Residues D532, H527, and D562 that form electrostatic interactions at the base of the loop containing basic residues K528, K531, and K533 are shown along with neighboring residues R485 and R488, equivalent to R484 and R487, respectively, involved in HS binding by AAV2. 3f-L584 is contributed from a 3-fold (3f) related VP3 monomer. The residues (in stick form) are colored according to atom type: carbon, yellow; nitrogen, blue; and oxygen, red. Dashed lines indicate the distance between interacting residues. Disruption of the D532-H527-D562 interaction by a D532N mutation is predicted to alter the conformation of the basic loop and in turn could alter AAV6 HS binding properties. (B) AAV2 residues E531, H526, D561, and E563 that form electrostatic interactions which stabilize an equivalent surface loop in this serotype containing residues K527, E530, and K532 and the neighboring amino acids, R484 and R487, involved in HS binding. Mutation of D561 and E563 to alanine disrupts HS binding in AAV2. 3f-L583 is contributed from a 3f VP3 monomer. Residues are colored as in panel A. (C) A superimposition of the residues shown in panels A and B with the AAV6 amino acids (labeled in black) shown according to atom type, as described for panels A and B, and those for AAV2 are colored blue (labeled in blue). This figure was generated using the PyMol program (14).