Simple usage
Keywords: manual

Next: More advanced usage Up: Automated comparative modeling with Previous: Automated comparative modeling with Contents Index

#
Simple usage

The simple example below constructs a single comparative model for the `1fdx` sequence from the known `5fd1` structure, using `alignment.ali`, a PIR format alignment of `5fd1` and `1fdx`. The final model is written into the PDB file `1fdx.B99990001.pdb`. See Section 1.6.2 for instructions on how to run this script.

Example: examples/automodel/model-default.py

      # Homology modeling by the automodel class
      from modeller import *              # Load standard Modeller classes
      from modeller.automodel import *    # Load the automodel class

      log.verbose()    # request verbose output
      env = environ()  # create a new MODELLER environment to build this model in

      # directories for input atom files
      env.io.atom_files_directory = './:../atom_files'

      a = automodel(env,
                    alnfile  = 'alignment.ali',     # alignment filename
                    knowns   = '5fd1',              # codes of the templates
                    sequence = '1fdx')              # code of the target
      a.starting_model= 1                 # index of the first model
      a.ending_model  = 1                 # index of the last model
                                          # (determines how many models to calculate)
      a.make()                            # do the actual homology modeling

Example: examples/automodel/alignment.ali

      C; A sample alignment in the PIR format; used in tutorial

      >P1;5fd1
      structureX:5fd1:1    : :106  : :ferredoxin:Azotobacter vinelandii: 1.90: 0.19
      AFVVTDNCIKCKYTDCVEVCPVDCFYEGPNFLVIHPDECIDCALCEPECPAQAIFSEDEVPEDMQEFIQLNAELA
      EVWPNITEKKDPLPDAEDWDGVKGKLQHLER*

      >P1;1fdx
      sequence:1fdx:1    : :54   : :ferredoxin:Peptococcus aerogenes: 2.00:-1.00
      AYVINDSC--IACGACKPECPVNIIQGS--IYAIDADSCIDCGSCASVCPVGAPNPED-----------------
      -------------------------------*

Stepping through the script, first we load the `automodel` class, using standard Python syntax to load a module. Next, we request verbose output (see Section 6.25) so that we can more easily spot errors. We then create an environ() object (see Section 6.2) and call it `env`. This object holds the MODELLER `environment', which comprises default values for many parameters, as well as the libraries used for comparative modeling (topology, parameters, dihedral classes, etc). An `environ` object is needed to create most other MODELLER objects, but you can call it whatever you like (it doesn't have to be called `env`).

Once we have the `environ` object, we can set some global parameters. In this case, we set io_data.atom_files_directory to set the directories to look for PDB files in.

Next, we create an `automodel` object, tell it which PIR alignment file to use, and which sequences are templates and which one we want to build a model for, and call it `a`. This doesn't actually build any models, but creates the object, ready to be tweaked for our purposes. In this case, we simply tell it to build a single model, by setting both automodel.starting_model and automodel.ending_model to 1. Finally, we actually build the model by running automodel.make().

Next: More advanced usage Up: Automated comparative modeling with Previous: Automated comparative modeling with Contents Index