Open AccessRegulation of the Legionella mip ‐promotor during infection of human monocytes
Author(s) -
Wieland Hagen,
Faigle Marion,
Lang Florian,
Northoff Hinnak,
Neumeister Birgid
Publication year - 2002
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2002.tb11255.x
Subject(s) - legionella , promoter , microbiology and biotechnology , monocyte , biology , virology , immunology , bacteria , genetics , gene , gene expression
The opportunistic pathogen Legionella pneumophila , the etiologic agent of Legionnaires disease, is able to invade and multiply intracellularly in human macrophages. This process is controlled by several bacterial virulence factors. As recently demonstrated, one of these virulence factors, the macrophage infectivity potentiator (Mip) protein, is important for invasion and proper intracellular establishment of L. pneumophila in macrophages and protozoa. Knockout mutants devoid of a functional mip ‐gene enter host cells much less effectively but intracellular replication is not affected. Using a P mip ‐green fluorescent protein reporter construct in L. pneumophila substrain Corby, P mip was recently shown to be constitutively active in replicating bacteria. A stringent regulation during the infection process could not be observed, neither in intracellular nor in BYE broth‐grown bacteria. For enhanced temporal and quantitative resolution, we examined the activity of mip on RNA level in order to detect short transient regulatory events. Our results show that P mip of L. pneumophila is temporarily repressed directly after invasion of the monocytic human cell line MonoMac 6 and regains activity after 24 h of intracellular replication.