Solute channels of the outer membrane: from bacteria to chloroplasts
| Autor: | Katrin Philippar, Jürgen Soll, Daniela Duy |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Transmembrane channels
Chloroplasts Endosymbiosis Cell Membrane Clinical Biochemistry Membrane Proteins Membrane Transport Proteins food and beverages Intracellular Membranes Biology Cyanobacteria Biochemistry Ion Channels General bacterial porin family Cell biology Chloroplast Bacterial Proteins Gram-Negative Bacteria Porin Voltage-Dependent Anion Channels Outer membrane efflux proteins Plastid Bacterial outer membrane Molecular Biology |
| Zdroj: | bchm. 388:879-889 |
| ISSN: | 1437-4315 1431-6730 |
| DOI: | 10.1515/bc.2007.120 |
| Popis: | Chloroplasts, unique organelles of plants, originated from endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. It is assumed that the outer envelope membrane, which delimits the chloroplast from the surrounding cytosol, was thus inherited from its Gram-negative bacterial ancestor. This plastid-specific membrane is thus equipped with elements of prokaryotic and eukaryotic origin. In particular, the membrane-intrinsic outer envelope proteins (OEPs) form solute channels with properties reminiscent of porins and channels in the bacterial outer membrane. OEP channels are characterised by distinct specificities for metabolites and a quite peculiar expression pattern in specialised plant organs and plastids, thus disproving the assumption that the outer envelope is a non-specific molecular sieve. The same is true for the outer membrane of Gram-negative bacteria, which functions as a permeability barrier in addition to the cytoplasmic membrane, and embeds different classes of channel pores. The channels of these prokaryotic prototype proteins, ranging from unspecific porins to specific channels to ligand-gated receptors, are exclusively built of β-barrels. Although most of the OEP channels are formed by β-strands as well, phylogeny based on sequence homology alone is not feasible. Thus, the comparison of structural and functional properties of chloroplast outer envelope and bacterial outer membrane channels is required to pinpoint the ancestral OEP ‘portrait gallery’. |
| Databáze: | OpenAIRE |
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