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. 2011 Oct;11(19):3935-41.
doi: 10.1002/pmic.201100103. Epub 2011 Aug 31.

A Reference Map of the Membrane Proteome of Enterococcus Faecalis

Free PMC article

A Reference Map of the Membrane Proteome of Enterococcus Faecalis

Gianluca Maddalo et al. Proteomics. .
Free PMC article


Enterococcus faecalis is a gram-positive bacterium that is part of the indigenous microbiotica of humans and animals as well as an opportunistic pathogen. In this study, we have fractionated the membrane proteome of E. faecalis and identified many of its constituents by mass spectrometry. We present blue native-/SDS-PAGE reference maps that contain 102 proteins. These proteins are important for cellular homeostasis, virulence, and antibiotic intervention. Intriguingly, many proteins with no known function were also identified, indicating that there are substantial gaps in the knowledge of this organism's biology. On a more limited scale, we also provide insight into the composition of membrane protein complexes. This study is a first step toward elucidating the membrane proteome of E. faecalis, which is critical for a better understanding of how this bacterium interacts with a host and with the extracellular milieu.

Conflict of interest statement

The authors declare no conflict of interests.


Figure 1
Figure 1. A birds-eye view of the membrane proteome of E. faecalis OG1X
(A) An overview of the methodology used in this study. A detailed description of all methodology is available in Supplementary Materials and Methods. Identified proteins were classified by (B) cellular location and (C) function.
Figure 2
Figure 2. Examples of membrane protein complexes that were identified
Cropped sections from the BN-/SDS-PAGE showing ‘vertical channels’ that contain proteins in known complexes. Only spots in a precise vertical channel can be part of the same complex. For the sake of clarity we have omitted annotations for proteins that are in close (but unrelated) channels. These spots were identified and are shown in Supplementary Figure 1. Soluble and membrane proteins were used to calibrate the protein complexes in the BN-PAGE (Supplementary Materials and Methods). As these two independent sets of proteins give significantly different calibration curves, we have calculated the molecular mass for each protein complex using both curves and reported a molecular mass range. All molecular mass markers are in kDa.

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