Updated project metadata. LCVs purified by immuno-magnetic separation and density gradient centrifugation (fraction 4) were resolved by 1D-SDS-PAGE, the gel lanes were excised in ten equidistant pieces and subjected to trypsin digestion. For the subsequent LC-MS/MS measurements, the digests were separated by reversed phase column chromatography using an EASYnLC apparatus with self-packed columns in a one-column setup. Following loading/ desalting in 0.1% acetic acid in water at a flow rate of 700 nL/min (maximum 220 bar), the peptides were separated by applying a binary non-linear gradient from 5-50% acetonitrile in 0.1% acetic acid over 70 min. The LC was coupled online to a LTQ-Velos Orbitrap mass spectrometer (Thermo Fisher, Bremen, Germany) at a spray voltage of 2.4 kV. After a survey scan in the Orbitrap (r = 30,000), MS/MS data were recorded for the twenty most intensive precursor ions in the linear ion trap. Singly charged ions were not taken into account for MS/MS analysis. The lock mass option was enabled throughout all analyses. After mass spectrometric measurement, MS data was converted into the mzxml format (version 3.1) by ReAdW version 4.3.1 and subsequently subjected to database searching via Sorcerer using Sequest (version 27, revision 11; SageN, Milptas, CA, USA) without charge state deconvolution and deisotoping performed. Database searching was performed either with a database of combined entries of L. pneumophila strain Philadelphia-1 (NC002942) and D. discoideum, or with a database of combined entries of L. pneumophila strain Philadelphia-1 and Mus musculus. Both databases were used as target/decoy databases with a list of common contaminants added (30739 and 64993 entries, respectively). Sequest was used assuming trypsinisation with a fragment ion mass tolerance of 1.00 Da and a search tolerance of 10 ppm for the overview scans. Oxidation of methionine was specified in Sequest as a variable modification. Scaffold (version 3.5.1, Proteome Software Inc., Portland, OR, USA) was used to filter and validate MS/MS-based peptide and protein identifications. Peptide identifications were accepted when spectra exceeded Xcorr values of 2.2, 3.3 and 3.8 for doubly, triply and quadruply peptides with deltaCN values of more than 0.1. Protein identifications are based on at least 2 unique peptides. Proteins that contained similar peptides and could not be differentiated based on MS/MS analysis alone were grouped to meet the principle of parsimony.