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Last Updated: 2/8/18

Description

This Mover computes which residues are lipid accessible and puts that information into the B-factors: 50 is lipid accessible, 0 is lipid INaccessible.

Code and Demo

The Mover lives in main/source/src/protocols/membrane/.

Algorithm: First, it sets the B-Factor to zero for all atoms. Then it computes concave and outer hulls and goes through the slices. Residues that are on the boundary are lipid-exposed. If the angle between COM-CA-CB is smaller than the cutoff, then it is not lipid-exposed.

RosettaScripts interface

The following options are available within the RosettaScript interface:

angle_cutoff - Real - Provide the angle cutoff. slice_width - Real - Provide the slice width. shell_radius - Real - Provide the shell radius. dist_cutoff - Real - Provide the distance cutoff. tm_alpha - bool - Provide the tm_alpha.

Flags / Options

Flag Description
-mp::lipid_acc::angle_cutoff <Real> Cutoff for CA-CB-COM angle to identify lipid accessible residues, in degrees. < 90 faces towards COM, > 90 faces away from COM. Default = 65. For smaller proteins like GPCRs (number of spans <= 7), default = 45.
-mp::lipid_acc::slice_width <Real> Width of the slice in Angstrom to compute hull. Default = 10.0.
-mp::lipid_acc::shell_radius <Real> Radius of shell from outermost atoms that are still counted as boundary, i.e. how thick is lipid-exposed layer from the outside. Default = 6.0.
-mp::lipid_acc::dist_cutoff <Real> Distances between boundary atoms longer than this cutoff (in 2D) will be cut in. Anything larger will be kept as boundary atoms. Default = 10.0.
-mp::lipid_acc::tm_alpha <Bool> Is the main secondary structure in the membrane helical? Default = true.

Reference

RosettaMP is described in

  • Alford RF, Koehler Leman J, Weitzner BD, Duran AM, Elazar A, Tilley DC, Gray JJ (2015) An integrated framework advancing membrane protein modeling and design, PLoS Computational Biology (in press)