ERRATUM
Volume 90, no. 12, p. 5759–5769, 2016. Page 5764, Fig. 3: Helix labels “α2,” “α3,” “α4,” “α5,” “α6,” “α7,” “α8,” “α9,” “α10,” and “α11” should read “η1,” “α2,” “α3,” “α4,” “α5,” “α6,” “α7,” “α8,” “α9,” and “α10,” respectively.
Figure 3 should appear as shown on the following page.