Document Detail


Differences in membrane fluidity and fatty acid composition between phenotypic variants of Streptococcus pneumoniae.
MedLine Citation:
PMID:  15231797     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Phase variation in the colonial opacity of Streptococcus pneumoniae has been implicated as a factor in the pathogenesis of pneumococcal disease. This study examined the relationship between membrane characteristics and colony morphology in a few selected opaque-transparent couples of S. pneumoniae strains carrying different capsular types. Membrane fluidity was determined on the basis of intermolecular excimerization of pyrene and fluorescence polarization of 1,6-diphenyl 1,3,5-hexatriene (DPH). A significant decrease, 16 to 26% (P < or = 0.05), in the excimerization rate constant of the opaque variants compared with that of the transparent variants was observed, indicating higher microviscosity of the membrane of bacterial cells in the opaque variants. Liposomes prepared from phospholipids of the opaque phenotype showed an even greater decrease, 27 to 38% (P < or = 0.05), in the pyrene excimerization rate constant compared with that of liposomes prepared from phospholipids of bacteria with the transparent phenotype. These findings agree with the results obtained with DPH fluorescence anisotropy, which showed a 9 to 21% increase (P < or = 0.001) in the opaque variants compared with the transparent variants. Membrane fatty acid composition, determined by gas chromatography, revealed that the two variants carry the same types of fatty acids but in different proportions. The trend of modification points to the presence of a lower degree of unsaturated fatty acids in the opaque variants compared with their transparent counterparts. The data presented here show a distinct correlation between phase variation and membrane fluidity in S. pneumoniae. The changes in membrane fluidity most probably stem from the observed differences in fatty acid composition.
Authors:
Barak Aricha; Itzhak Fishov; Zvi Cohen; Noga Sikron; Stella Pesakhov; Inna Khozin-Goldberg; Ron Dagan; Nurith Porat
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of bacteriology     Volume:  186     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-07-02     Completed Date:  2004-08-23     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4638-44     Citation Subset:  IM    
Copyright Information:
Copyright 2004 American Society for Microbiology
Affiliation:
Pediatric Infectious Disease Unit, Soroka University Medical Center, P.O. Box 151, Beer Sheva 84101, Israel. npurat@bgumail.bgu.ac.il
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MeSH Terms
Descriptor/Qualifier:
Cell Membrane / chemistry*
Chromatography, Gas
Diphenylhexatriene / chemistry,  metabolism
Fatty Acids / analysis*,  physiology
Fatty Acids, Unsaturated / analysis
Fluorescence Polarization
Genetic Variation*
Liposomes / chemistry
Membrane Fluidity*
Membrane Lipids / analysis
Phenotype
Phospholipids / analysis
Pyrenes / chemistry,  metabolism
Streptococcus pneumoniae / genetics*,  physiology*
Chemical
Reg. No./Substance:
0/Fatty Acids; 0/Fatty Acids, Unsaturated; 0/Liposomes; 0/Membrane Lipids; 0/Phospholipids; 0/Pyrenes; 129-00-0/pyrene; 1720-32-7/Diphenylhexatriene
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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