immunology of infectious and parasitic diseases - XXXVII Congress ...

THE ROLE OF K + TRANSPORTERS IN THE Legionella pneumophila
REPLICATION
JULIANA ISSA HORI 1 AND DARIO SIMÕES ZAMBONI 1 .
(1). Department of Cellular and Molecular Biology, School of Medicine of
Ribeirão Preto, University of São Paulo (FMRP/USP).
Introduction: Legionella pneumophila is a facultative intracellular bacteria
found ubiquitously in lakes and rivers where parasitizes a broad number of
amoebae species. Potassium is an essential nutrient for organisms and certain
bacterial species, such as L. pneumophila, requires large amounts of potassium
to replicate. It is known that bacteria, as well as plants, accumulate potassium
by a number of different transport systems that vary in kinetics, energy coupling,
and regulation. So, we investigate the role of L. pneumophila K+ transporters
during bacteria growth in macrophages and in axenic media.
Methods and Results: In silico analysis of the L. pneumophila genomic
revealed that the bacterium presents three genes predicted to encode K+
transporters. These genes showed strong sequence similarity to Kup family K+
transporters that are highly conserved among different organisms. To evaluate
the expression of these genes in L. pneumophila we performed reverse
transcriptase-PCR analyses and found that the bacteria express them all. By
measuring the K + concentrations in the media we found that KupA is a
functional K+ transporter and its absence does not interfere with bacterial
growth in axenic medium and bacterial multiplication in Acanthamoeba
castellanii. In contrast, kupA was required to the early multiplication in mouse
macrophages and this defect was correlated with a defect in the establishment
of the LCV (Legionella Containing Vacuole).
Conclusion: Collectively, our data indicates that L. pneumophila expresses
three gene products predicted to function as K + transporter; KupA is a functional
K + transporter required for bacterial replication in macrophages.
Supported by: FAPESP and INCTV/CNPq.