Indeed, the amount of GalE measured by Western blot analysis stayed almost the same starting from late exponential to stationary phase while those of GalT and GalK decreased, supporting our notion that cells need to maintain a certain concentration of GalE against decreasing mRNA level during stationary phase.. Inhalation of L. pneumophila contaminated aerosols by immuno-compromised individuals can lead to an atypical acute pneumonia known as Legionnaires’ disease. The cell biological features associated with infections of amoeba and mammalian cells are highly similar, suggesting that amoeba serves as the “training site” for its ability to colonize higher organisms. Similarly, most genetic determinants important for multiplying within amoebae cells also are essential for its growth in mammalian cells. The single most important virulence factor of L. pneumophila is the Dot/ Icm type IV secretion system. Built with about 26 proteins, this apparatus connects the bacterial cytoplasm to the extracellular environment and functions as the conduit through which effector proteins are delivered into host cells. Protein R428 1037624-75-1 substrates of the Dot/Icm are directly involved in the construction of the niche called Legionella containing vacuole that supports intracellular bacterial growth. Elucidating the functions of these substrates will reveal not only the mechanisms used by L. pneumophila to subvert host cellular processes but also could potentially reveal novel host pathways undetectable or difficult to study under normal physiological conditions. Thus, tremendous efforts have been invested to identify such effector proteins, characterize their functions, and to understand their roles in L. pneumophila pathogenesis. Candidate genes used in these translocation assays were obtained by a number of strategies, including bioinformatics analyses to retrieve proteins harboring structural features or functional domains typically found in proteins of eukaryotes origins ; second, proteins that physically interact with components of the Dot/Icm complex or chaperones ; third, proteins capable of disrupting cellular processes of Saccharomyces cerevisiae ; fourth, proteins whose expression appears to be regulated similarly to known substrates ; fifth, computational tools to search for proteins which have one or more of the above features. The combination of these gene search methods and the use of one or more translocation reporter systems have led to the identification of 204 proteins transferred by Dot/Icm. A hydrophobic residue at the -3rd position and the E-block are the two known features important for Dot/Icmdependent translocation of subsets of substrates. Other characteristics, such as frequent occurrence of small side-chain residues at 11th to -5th residues, and a polar residue at the -16th position had been found in many substrates. Whether these features are important for protein translocation is unknown. Dot/Icm.