Title: The Escherichia coli Peripheral Inner Membrane Proteome
Authors: Papanastasiou, Malvina ×
Orfanoudaki, Georgia
Koukaki, Marina
Kountourakis, Nikos
Sardis, Marios Frantzeskos
Aivaliotis, Michalis
Karamanou, Spyridoula
Economou, Anastassios #
Issue Date: Mar-2013
Publisher: American Society for Biochemistry and Molecular Biology
Series Title: Molecular & Cellular Proteomics vol:12 issue:3 pages:599-610
Article number: 10.1074/mcp.M112.024711
Abstract: Biological membranes are essential for cell viability. Their functional characteristics strongly depend on their protein content, which consists of transmembrane (integral) and peripherally associated membrane proteins. Both integral and peripheral inner membrane proteins mediate a plethora of biological processes. Whereas transmembrane proteins have characteristic hydrophobic stretches and can be predicted using bioinformatics approaches, peripheral inner membrane proteins are hydrophilic, exist in equilibria with soluble pools, and carry no discernible membrane targeting signals. We experimentally determined the cytoplasmic peripheral inner membrane proteome of the model organism Escherichia coli using a multidisciplinary approach. Initially, we extensively re-annotated the theoretical proteome regarding subcellular localization using literature searches, manual curation, and multi-combinatorial bioinformatics searches of the available databases. Next we used sequential biochemical fractionations coupled to direct identification of individual proteins and protein complexes using high resolution mass spectrometry. We determined that the proposed cytoplasmic peripheral inner membrane proteome occupies a previously unsuspected ∼19% of the basic E. coli BL21(DE3) proteome, and the detected peripheral inner membrane proteome occupies ∼25% of the estimated expressed proteome of this cell grown in LB medium to mid-log phase. This value might increase when fleeting interactions, not studied here, are taken into account. Several proteins previously regarded as exclusively cytoplasmic bind membranes avidly. Many of these proteins are organized in functional or/and structural oligomeric complexes that bind to the membrane with multiple interactions. Identified proteins cover the full spectrum of biological activities, and more than half of them are essential. Our data suggest that the cytoplasmic proteome displays remarkably dynamic and extensive communication with biological membrane surfaces that we are only beginning to decipher.
ISSN: 1535-9476
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular Bacteriology (Rega Institute)
× corresponding author
# (joint) last author

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