![]() Proceed to the next step to complete the assembly. A pop-up window will be displayed where one can visually inspect the structure (Fig. Click the "view structure" link next to the Component PDB file link. ![]() If this step is not working the instructor will provide pre-calculated files.ĬHARMM-GUI will display the list of prepared files (Fig. Proceed to the next step to combine membrane components. This could be a problem that will not be resolved by minimization and the system has to be regenerated. Proceed to the next step.ĬHARMM-GUI reports on possible lipid penetrations of rings (not shown). Select CaCl 2 as the salt of choice (Fig. As for the ions, we will use calcium ions for system neutralization and additional concentration. We will use the default Replacement method. The system size summary will be displayed (not shown) as well as two choices for protein insertion into the membrane (Fig. Click again the "Show the system info" button. Observe that summary now has list of lipids (Fig. Remark: for E.coli outer membrane composition composition see e.g., Lugtenberg EJJ & Peters R, BBA, 441, 38–47, 1976. Click the "Show the system info" button to update. Hover over the links "Image" in the row of the chosen lipids and lipid structure will be shown. As a reminder, PE is a zwitterionic (formally neutral) while PG is charged lipid. Enter "90" in the upper and lower leaflet boxes for POPE, and "10" in the upper and lower leaflet boxes for POPG. 6): Build a membrane consisting of phosphatidylethanolamine (POPE) 90% and phosphatidylglycerol (POPG) 10%, which will be our model for the outer membrane of E. Select lipids under the clickable triangles (Fig. We can keep the default value of the water thickness at 17.5 Å. The results of the estimate will be shown in the table (Fig. 5, left) and click the "Show the system info" button. Enter 50 Å as the initial estimate for the size of the cell (Fig. Cross sectional density will be displayed (not shown) as well as system size options (Fig. Proceed to the next step.ġ.2 CHARMM-GUI: select lipids and water thickness. 4) – this assumes the Z-axis is aligned with the principal axis of inertia of the protein. Keep the PDB orientation as a choice (Fig. Open the CHARMM-GUI website () and go to Input Generator –> Membrane Builder –> Bilayer Builder.ġ.1 CHARMM-GUI: load, analyze, and position PDBĬHARMM-GUI provides choice for protein orientation in the membrane. Small modifications might be needed when used on other computers. This tutorial can be completed on iMacs in the SCS VizLab (151 Noyes Lab) or with personal computers with Windows or Mac OS. MobaXTerm for a Windows machine), and CHARMM-GUI web server. Personal computer: Terminal (Mac OSX) or xserver (e.g. Step 4: when job is completed, analyze the results. Step 3: submit the system to the local computer cluster Step 2: download the system to local desktop computer ![]() Step 1: prepare membrane-OmpLA structure using CHARMM-GUI web-server For info on the cluster see SCS Clusters webpage. Outline: we will use the SCS computer cluster to model the systems. CHARMM-GUI is developed by the Im Lab at the Lehigh University ( ).Įstimated time to complete this tutorial is 1.5 hr. Note: NAMD and VMD are developed at the NIH Center for Macromolecular Modeling hosted at the University of Illinois at Urbana-Champaign ( ). In a recent experimental study, the Fleming Lab (Johns Hopkins) used spontaneous folding of OmpLA into the membrane to design a hydrophobicity scale (Moon PC and Fleming KG, PNAS 108, 10174, 2011). The system of interest will be the outer membrane phospholipase A from E. This tutorial is designed to introduce the preparation, modeling, and analysis of membrane-protein system with molecular dynamics (MD) using NAMD, VMD, and CHARMM-GUI. School of Chemical Sciences, University of Illinois Urbana-ChampaignĪugust 17, 2016, Edition 1.1. Basics of membrane-protein interactions using molecular dynamics with NAMD, VMD, and CHARMM-GUI
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