Figure 3
From: Structural insights into phosphatidylethanolamine formation in bacterial membrane biogenesis
N-terminal three-helices are crucial for membrane binding and auto-cleavage. (A) Amphipathic nature of N-terminal helices are displayed in light green and the hydrophobic residues are labeled and highlighted in dark green. (B) Membrane association assay of PSD full-length (WT, 1–322), α1-helix (ΔH1, 13–322), α1–2 (ΔH2, 30–322), and α1–3 truncated (ΔH3, 46–322). The proteins were heterologously expressed in E. coli. The cells were lysed by sonication in non-detergent solution (PBS, phosphate-buffered saline), and separated into soluble, membrane, and inclusion body (IB) fractions by sequential rounds of centrifuge and ultracentrifuge. Each fractions were analyzed by 12% SDS-PAGE and western blotting using anti-histag antibody. Lane M ladder marker. (C) Distribution of electrostatic potential on αβ-heterotetramer. Left and right, two views are same as in Fig. 2A. The surface with positive charge is displayed in blue, negative in red, and neutral in white. Approximate location of cell membrane is shown as gray box. N-terminal three-helices are designated on the left panel.
