| Phospholipid flip-out controls the cell cycle of Escherichia coli. | |
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MedLine Citation:
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PMID: 2687587 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Phospholipids are the principal constituents of biological membranes. In Escherichia coli, phospholipids are involved in the metabolism of other envelope constituents such as lipoprotein, lipopolysaccharide, certain envelope proteins and peptidoglycan. They are also involved in the regulation of the cell cycle. DNAA, the key protein in the initiation of chromosome replication, is activated by acidic phospholipids only when these are in fluid bilayers, whilst interruptions of phospholipid synthesis inhibit both the initiation of chromosome replication and cell division. The transmembrane movement or flip-flop of phospholipids from one monolayer to the other requires the passage of the polar head group through the hydrophobic core of the bilayer. Hence, in many systems, flip-flop is a slow process with half-time of days. Flip-flop accompanies the formation of non-bilayer structure. Such structures form under certain conditions of packing density and composition and have been observed both in vitro and in vivo. In bacteria, flip-flop appears to be extremely rapid, with half-times as fast as 3 min being observed. However, such rapid flip-flop may not be characteristic of all phospholipids. The asymmetrical distribution of phosphatidylethanolamine in the plasma membrane of Bacillus megaterium has been attributed to the existence of two classes of this phospholipid. In E. coli, studies of the metabolic turnover of phosphatidylserine, phosphatidylglycerol and phosphatidic acid also reveal the existence of distinct classes of these phospholipids. In this article I propose that, in E. coli, a class of phospholipids does indeed escape the rapid flip-flop mechanism; this class probably includes a subpopulation of the acidic phospholipids. Therefore during the cell cycle these phospholipids accumulate in the inner monolayer of the cytoplasmic membrane and so cause an increase in its packing density; at a critical density, phospholipids "flip out" from the inner to the outer monolayer. This flip-out occurs once per cycle and initiates cell cycle events. |
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Authors:
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V Norris |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of theoretical biology Volume: 139 ISSN: 0022-5193 ISO Abbreviation: J. Theor. Biol. Publication Date: 1989 Jul |
Date Detail:
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Created Date: 1990-01-24 Completed Date: 1990-01-24 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0376342 Medline TA: J Theor Biol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 117-28 Citation Subset: IM |
Affiliation:
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Department of Genetics, University of Leicester, U.K. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Cell Cycle* Escherichia coli / cytology* Phospholipids / physiology* |
| Chemical | |
Reg. No./Substance:
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0/Phospholipids |
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