Figure 3: Unfolding of CNB domain. | Nature Communications

Figure 3: Unfolding of CNB domain.

From: Conformational rearrangements in the transmembrane domain of CNGA1 channels revealed by single-molecule force spectroscopy

Figure 3

(a) Schematic representation of the unfolding sequence, with the expected Lc values and the relative a.a. length in parenthesis and single module of I27 (cyan triangle), CNB domain (green rectangle), C-linker (green oval), transmembrane domains (cyan rectangles) and mutation P366C (red dots). (b) (F,Lc) plot from a typical curve of P366C-(I27)2-HisTag. The finger print is composed by two force peaks of ∼200 pN separated by ∼28 nm with the detachment peak, with a value of Lc corresponding to unfolding of the cytoplasmic domain from D690 to P366 and the two I27 modules (that is, (D690−P366)·0.4 nm+2·28 nm))=186 nm. (c) Superimposition of the F–D curves of CNGA1 (red), P366C-HisTag (cyan) and P366C-(I27)2-HisTag (black). The F–D curves from the construct P366C-HisTag are shorter than those from CNGA1 and have a detachment event at 120–140 nm. Force peaks with Lc values at 96 and 116 nm are present in the F–D curves from the CNGA1, P366C-HisTag and P366C-(I27)2-HisTag constructs. (d) Different unfolding pathways in the open and closed states; I and II: superposition of the F–D curves from CNGA1 channels (red) and from the construct P366C-(I27)2-HisTag (black) in the closed state. In I, there are two force peaks with Lc values of 96 and 116 nm, but there is only one force peak in II; III and IV: superposition of the F–D curves from CNGA1 channels (blue) and from the constructs P366C-(I27)2-HisTag (green) in the open state. In III there are three force peaks with Lc values of 54, 84 and 116 nm, and in IV there are three force peaks with Lc values of 84, 96 and 118 nm. The force peak with an Lc of 158 is only present in the construct P366C-(I27)2-HisTag. (e) Superimposition of histograms of normalized counts/bin against Lc from the F–D curves obtained from P366C-(I27)2-HisTag (black) and from CNGA1 channels (red) in the closed state (f) same as in e for P366C-(I27)2-HisTag (green) and from CNGA1 channels (blue) in the open state. The data in e,f are from CNGA1 channels as described in Figs 1 and 2.

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