3T1T: Mgla Bound To Gdp In P1 Tetrameric Arrangement

The bacterium Myxococcus xanthus uses a G protein cycle to dynamically regulate the leading/lagging pole polarity axis. The G protein MglA is regulated by its GTPase-activating protein (GAP) MglB, thus resembling Ras family proteins. Here, we show structurally and biochemically that MglA undergoes a dramatic, GDP-GTP-dependent conformational change involving a screw-type forward movement of the central beta2-strand, never observed in any other G protein. This movement and complex formation with MglB repositions the conserved residues Arg53 and Gln82 into the active site. Residues required for catalysis are thus not provided by the GAP MglB, but by MglA itself. MglB is a Roadblock/LC7 protein and functions as a dimer to stimulate GTP hydrolysis in a 2:1 complex with MglA. In vivo analyses demonstrate that hydrolysis mutants abrogate Myxococcus' ability to regulate its polarity axis changing the reversal behaviour from stochastic to oscillatory and that both MglA GTPase activity and MglB GAP catalysis are essential for maintaining a proper polarity axis.
PDB ID: 3T1TDownload
MMDB ID: 93358
PDB Deposition Date: 2011/7/22
Updated in MMDB: 2011/11
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 3T1T: monomeric; determined by author and by software (PISA)
Molecular Components in 3T1T
Label Count Molecule
Protein (1 molecule)
Gliding Protein Mgla
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB