Fig. 2: Crystal structures of the paLptDE-LptM and apo-paLptDE complex.
From: Surface lipoprotein sorting by crosstalk between Lpt and Lol pathways in gram-negative bacteria
A Schematic structures of paLptD (green), paLptE (magenta) and LptM (orange). The two conserved inter-domain disulfide bonds (yellow) and the jellyroll-barrel connecting loop (residues P316-P328, red) in paLptD are labeled and highlighted, respectively. The signal peptides of paLptD (residues 1-33), paLptE (residues 1–19) and LptM (residues 1–19) are labeled. B Crystal structure of the paLptDE-LptM (left) and apo-paLptDE (right) complex. The paLptD (green) and paLptE (magenta) are shown in cartoon. Unbiased Fo − Fc difference Fourier electron density (blue mesh, contoured at 2.0 σ) calculated before modeling LptM molecule. C Zoomed-in view of the atomic model of LptM superimposed with the electron density. The LptM (stick mode) was placed in the electron densities, showing that the electron density fragment in the paLptD barrel displays polypeptide features with bulky side chains (left top insert). The jellyroll-barrel connecting loop and the two pairs of disulfide bonds are highlighted in red and magenta, respectively. Numbering of the LptM residues in the structure follows the nomenclature of bacterial lipoproteins (left bottom insert). D Close-up view of the LptM-paLptDE interactions. Residues of paLptD (F281, I313, Y314, F325, I892, L894 and L897, in green) that interact with the three acyl chains (R1, R2 and R3) are shown in stick mode (left panel); residues of paLptD (Q322, Y357, E371, R373, I900 and V901, in green) that interact with the proteinaceous part of LptM are also shown in stick mode and labeled (right panel). LptM is shown in stick mode (brown). R1, R2 and R3 stand for three acyl chains of LptM.
