Identification of the essential Brucella melitensis porin Omp2b as a suppressor of Bax-induced cell death in yeast in a genome-wide screening.
BACKGROUND
Inhibition of apoptosis is one of the mechanisms selected by numerous intracellular pathogenic bacteria to control their host cell. Brucellae, which are the causative agent of a worldwide zoonosis, prevent apoptosis of infected cells, probably to support survival of their replication niche.


RESULTS
In order to identify Brucella melitensis anti-apoptotic effector candidates, we performed a genome-wide functional screening in yeast. The B. melitensis ORFeome was screened to identify inhibitors of Bax-induced cell death in S. cerevisiae. B. melitensis porin Omp2b, here shown to be essential, prevents Bax lethal effect in yeast, unlike its close paralog Omp2a. Our results based on Omp2b size variants characterization suggest that signal peptide processing is required for Omp2b effect in yeast.


CONCLUSIONS
We report here the first application to a bacterial genome-wide library of coding sequences of this "yeast-rescue" screening strategy, previously used to highlight several new apoptosis regulators. Our work provides B. melitensis proteins that are candidates for an anti-apoptotic function, and can be tested in mammalian cells in the future. Hypotheses on possible molecular mechanisms of Bax inhibition by the B. melitensis porin Omp2b are discussed.
Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium.
Géraldine
G
Laloux
Michaël
M
Deghelt
Marie
M
de Barsy
Jean-Jacques
JJ
Letesson
Xavier
X
De Bolle
D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology; D017347:Brucella melitensis / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology*; D016681:Genome, Fungal; D016366:Open Reading Frames; D018272:Porins / Q000378:metabolism* / Q000502:physiology; D015003:Yeasts / Q000235:genetics / Q000502:physiology*; D051028:bcl-2-Associated X Protein / Q000502:physiology*
D001426:Bacterial Proteins; C096736:Omp2b protein, Brucella; D018272:Porins; D051028:bcl-2-Associated X Protein