Universität zu Köln

Riyahi, Tanja Y., Frese, Frederike, Steinert, Michael, Omosigho, Napoleon N., Gloeckner, Gernot, Eichinger, Ludwig ORCID: 0000-0003-1594-6117, Orabi, Benoit, Williams, Robin S. B. and Noegel, Angelika A. (2011). RpkA, a Highly Conserved GPCR with a Lipid Kinase Domain, Has a Role in Phagocytosis and Anti-Bacterial Defense. PLoS One, 6 (11). SAN FRANCISCO: PUBLIC LIBRARY SCIENCE. ISSN 1932-6203

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Abstract

RpkA (Receptor phosphatidylinositol kinase A) is an unusual seven-helix transmembrane protein of Dictyostelium discoideum with a G protein coupled receptor (GPCR) signature and a C-terminal lipid kinase domain (GPCR-PIPK) predicted as a phosphatidylinositol-4-phosphate 5-kinase. RpkA-homologs are present in all so far sequenced Dictyostelidae as well as in several other lower eukaryotes like the oomycete Phytophthora, and in the Legionella host Acanthamoeba castellani. Here we show by immunofluorescence that RpkA localizes to endosomal membranes and is specifically recruited to phagosomes. RpkA interacts with the phagosomal protein complex V-ATPase as proteins of this complex co-precipitate with RpkA-GFP as well as with the GST-tagged PIPK domain of RpkA. Loss of RpkA leads to a defect in phagocytosis as measured by yeast particle uptake. The uptake of the pathogenic bacterium Legionella pneumophila was however unaltered whereas its intracellular replication was significantly enhanced in rpkA(-). The difference between wild type and rpkA(-) was even more prominent when L. hackeliae was used. When we investigated the reason for the enhanced susceptibility for L. pneumophila of rpkA(-) we could not detect a difference in endosomal pH but rpkA(-) showed depletion of phosphoinositides (PIP and PIP2) when we compared metabolically labeled phosphoinositides from wild type and rpkA(-). Furthermore rpkA(-) exhibited reduced nitrogen starvation tolerance, an indicator for a reduced autophagy rate. Our results indicate that RpkA is a component of the defense system of D. discoideum as well as other lower eukaryotes.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Riyahi, Tanja Y. UNSPECIFIED UNSPECIFIED UNSPECIFIED Frese, Frederike UNSPECIFIED UNSPECIFIED UNSPECIFIED Steinert, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Omosigho, Napoleon N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gloeckner, Gernot UNSPECIFIED UNSPECIFIED UNSPECIFIED Eichinger, Ludwig UNSPECIFIED orcid.org/0000-0003-1594-6117 UNSPECIFIED Orabi, Benoit UNSPECIFIED UNSPECIFIED UNSPECIFIED Williams, Robin S. B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Noegel, Angelika A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-485568
DOI:	10.1371/journal.pone.0027311
Journal or Publication Title:	PLoS One
Volume:	6
Number:	11
Date:	2011
Publisher:	PUBLIC LIBRARY SCIENCE
Place of Publication:	SAN FRANCISCO
ISSN:	1932-6203
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LEGIONELLA-PNEUMOPHILA; DICTYOSTELIUM-DISCOIDEUM; PHOSPHOINOSITIDE METABOLISM; INTRACELLULAR GROWTH; PHAGOSOME MATURATION; LEGIONNAIRES-DISEASE; DRINKING-WATER; SOCIAL AMEBAS; VALPROIC ACID; HELA-CELLS Multiple languages Multidisciplinary Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48556