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EMBO J. 2012 Apr 4;31(7):1774-84. doi: 10.1038/emboj.2012.16. Epub 2012 Feb 3.

Reversible phosphocholination of Rab proteins by Legionella pneumophila effector proteins.

Author information

1
Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.

Abstract

The Legionella pneumophila protein AnkX that is injected into infected cells by a Type IV secretion system transfers a phosphocholine group from CDP-choline to a serine in the Rab1 and Rab35 GTPase Switch II regions. We show here that the consequences of phosphocholination on the interaction of Rab1/Rab35 with various partner proteins are quite distinct. Activation of phosphocholinated Rabs by GTP/GDP exchange factors (GEFs) and binding to the GDP dissociation inhibitor (GDI) are strongly inhibited, whereas deactivation by GTPase activating proteins (GAPs) and interactions with Rab-effector proteins (such as LidA and MICAL-3) are only slightly inhibited. We show that the Legionella protein lpg0696 has the ability to remove the phosphocholine group from Rab1. We present a model in which the action of AnkX occurs as an alternative to GTP/GDP exchange, stabilizing phosphocholinated Rabs in membranes in the GDP form because of loss of GDI binding ability, preventing interactions with cellular GTPase effectors, which require the GTP-bound form. Generation of the GTP form of phosphocholinated Rab proteins cannot occur due to loss of interaction with cellular GEFs.

PMID:
22307087
PMCID:
PMC3321196
DOI:
10.1038/emboj.2012.16
[Indexed for MEDLINE]
Free PMC Article

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