Article
Endocytosis-like protein uptake in the bacterium Gemmata obscuriglobus.
School of Chemistry and Molecular Biosciences, Australian Research Council Centre of Excellence for Integrative Legume Research, University of Queensland, St. Lucia, Queensland 4072, Australia.
Proceedings of the National Academy of Sciences (impact factor:
9.68).
07/2010;
107(29):12883-8.
DOI:10.1073/pnas.1001085107
pp.12883-8
Source: PubMed
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Citations (0)
- Cited In (5)
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Article: Protein uptake by bacteria: An endocytosis-like process in the planctomycete Gemmata obscuriglobus.
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ABSTRACT: Endocytosis is a fundamental process of membrane-trafficking in eukaryotes, but has not been known to occur in bacteria or archaea. The origin of endocytosis is central to the understanding of evolution of the first eukaryotes and their endomembrane systems. In a recent study we have established that an endocytosis-like process for uptake of proteins into cells occurs in a bacterium, Gemmata obscuriglobus, a member of the distinctive phylum Planctomycetes of peptidoglycan-less budding bacteria. Members of this phylum characteristically possess cells divided into compartments separated by internal membranes and in the case of G. obscuriglobus these compartments include one where a double membrane envelope surrounds its nucleoid DNA, as well as an outer ribosome- free region of cytoplasm. Proteins can be internalized by cells from the external milieu and collected into this ribosome-free compartment, and this process is energy-dependent and appears to be receptor-mediated. As in eukaryote endocytosis, internalized proteins are associated with vesicles, and can be subjected to proteolytic degradation. The discovery of this process in a bacterium has significant implications for our understanding of the origins of endocytosis in eukaryotes.Communicative & integrative biology 11/2010; 3(6):572-5. -
Article: The N-terminal amphipathic helix of the topological specificity factor MinE is associated with shaping membrane curvature.
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ABSTRACT: Pole-to-pole oscillations of the Min proteins in Escherichia coli are required for the proper placement of the division septum. Direct interaction of MinE with the cell membrane is critical for the dynamic behavior of the Min system. In vitro, this MinE-membrane interaction led to membrane deformation; however, the underlying mechanism remained unclear. Here we report that MinE-induced membrane deformation involves the formation of an amphipathic helix of MinE(2-9), which, together with the adjacent basic residues, function as membrane anchors. Biochemical evidence suggested that the membrane association induces formation of the helix, with the helical face, consisting of A2, L3, and F6, inserted into the membrane. Insertion of this helix into the cell membrane can influence local membrane curvature and lead to drastic changes in membrane topology. Accordingly, MinE showed characteristic features of protein-induced membrane tubulation and lipid clustering in in vitro reconstituted systems. In conclusion, MinE shares common protein signatures with a group of membrane trafficking proteins in eukaryotic cells. These MinE signatures appear to affect membrane curvature.PLoS ONE 01/2011; 6(6):e21425. · 4.09 Impact Factor -
Article: Lateral transfer of tetrahymanol-synthesizing genes has allowed multiple diverse eukaryote lineages to independently adapt to environments without oxygen.
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ABSTRACT: Sterols are key components of eukaryotic cellular membranes that are synthesized by multi-enzyme pathways that require molecular oxygen. Because prokaryotes fundamentally lack sterols, it is unclear how the vast diversity of bacterivorous eukaryotes that inhabit hypoxic environments obtain, or synthesize, sterols. Here we show that tetrahymanol, a triterpenoid that does not require molecular oxygen for its biosynthesis, likely functions as a surrogate of sterol in eukaryotes inhabiting oxygen-poor environments. Genes encoding the tetrahymanol synthesizing enzyme squalene-tetrahymanol cyclase were found from several phylogenetically diverged eukaryotes that live in oxygen-poor environments and appear to have been laterally transferred among such eukaryotes.Biology Direct 02/2012; 7:5. · 4.02 Impact Factor
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Keywords
ancestral noneukaryote cell
Archaea
autogenous evolution
Bacteria
endocytosis
energy-dependent process analogous
eukaryotic endocytosis
external milieu
extracellular material
internalized proteins
intracellular membranes
membrane trafficking
membrane-trafficking system
phylum Planctomycetes
planctomycete Gemmata obscuriglobus
universal
uptake proteins present
vesicle membranes
