1. Proteomics. 2009 Oct 15;9(24):5484-5496. [Epub ahead of print]

Isolation and 2-D-DIGE proteomic analysis of intracellular and extracellular
forms of Listeria monocytogenes.

Van de Velde S, Delaive E, Dieu M, Carryn S, Van Bambeke F, Devreese B, Raes M,
Tulkens PM.

Unité de pharmacologie cellulaire et moléculaire, Louvain Drug Research
Institute, Université catholique de Louvain, Brussels, Belgium.

The pathogenicity of Listeria monocytogenes is related to its ability of invading
and multiplying in eukaryotic cells. Its main virulence factors are now well
characterized, but limited proteomic data is available concerning its adaptation 
to the intracellular environment. In this study, L. monocytogenes EGD (serotype
1/2a) grown in human THP-1 monocytes (24 h) were successfully separated from host
organelles and cytosolic proteins by differential and isopycnic centrifugation.
For control, we used cell homogenates spiked with bacteria grown in broth.
Proteomes from both forms of bacteria were compared using a 2-D-DIGE approach
followed by MALDI-TOF analysis to identify proteins. From 1684 distinct spots,
448 were identified corresponding to 245 distinct proteins with no apparent
contamination of host proteins. Amongst them, 61 show underexpression (stress
defense; transport systems, carbon metabolism, pyrimidines synthesis, D-Ala-D-Ala
ligase) and 22 an overexpression (enzymes involved in the synthesis of cell
envelope lipids, glyceraldehyde-3-phosphate, pyruvate and fatty acids). Our
proteomic analysis of intracellular L. monocytogenes (i) suggests that bacteria
thrive in a more favorable environment than extracellularly, (ii) supports the
concept of metabolic adaptation of bacteria to intracellular environment and
(iii) may be at the basis of improved anti-Listeria therapy.

PMID: 19834917 [PubMed - as supplied by publisher]