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Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):4221-6. Epub 2003 Mar 17.

Ring-like pore structures of SecA: implication for bacterial protein-conducting channels.

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1
Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembranes, Tsinghua University, Beijing 100084, China.

Abstract

SecA, an essential component of the general protein secretion pathway of bacteria, is present in Escherichia coli as soluble and membrane-integral forms. Here we show by electron microscopy that SecA assumes two characteristic forms in the presence of phospholipid monolayers: dumbbell-shaped elongated structures and ring-like pore structures. The ring-like pore structures with diameters of 8 nm and holes of 2 nm are found only in the presence of anionic phospholipids. These ring-like pore structures with larger 3- to 6-nm holes (without staining) were also observed by atomic force microscopic examination. They do not form in solution or in the presence of uncharged phosphatidylcholine. These ring-like phospholipid-induced pore-structures may form the core of bacterial protein-conducting channels through bacterial membranes.

PMID:
12642659
PMCID:
PMC153074
DOI:
10.1073/pnas.0737415100
[Indexed for MEDLINE]
Free PMC Article
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