Document Detail

Insertion of fluorescent fatty acid probes into the outer membranes of the pathogenic spirochaetes Treponema pallidum and Borrelia burgdorferi.
MedLine Citation:
PMID:  11320119     Owner:  NLM     Status:  MEDLINE    
The authors examined the ability of octadecanoyl (C(18)), hexadecanoyl (C(16)) and dodecanoyl (C(12)) fatty acid (FA) conjugates of 5-aminofluorescein (OAF, HAF and DAF, respectively) to insert into the outer membranes (OMs) of Treponema pallidum, Borrelia burgdorferi and Escherichia coli. Biophysical studies have demonstrated that these compounds stably insert into phospholipid bilayers with the acyl chain within the hydrophobic interior of the apical leaflet and the hydrophilic fluorescein moiety near the phospholipid head groups. Consistent with the known poor intrinsic permeability of the E. coli OM to hydrophobic compounds and surfactants, E. coli was not labelled with any of the FA probes. OAF inserted more readily into OMs of B. burgdorferi than into those of T. pallidum, although both organisms were completely labelled at concentrations at or below 2 microg ml(-1). Intact spirochaetes were labelled with OAF but not with antibodies against known periplasmic antigens, thereby confirming that the probe interacted exclusively with the spirochaetal OMs. Separate experiments in which organisms were cooled to 4 degrees C (i.e. below the OM phase-transition temperatures) indicated that labelling with OAF was due to insertion of the probe into the OMs. B. burgdorferi, but not T. pallidum, was labelled by relatively high concentrations of HAF and DAF. Taken as a whole, these findings support the prediction that the lack of lipopolysaccharide renders T. pallidum and B. burgdorferi OMs markedly more permeable to lipophilic compounds than their Gram-negative bacterial counterparts. The data also raise the intriguing possibility that these two pathogenic spirochaetes obtain long-chain FAs, nutrients they are unable to synthesize, by direct permeation of their OMs.
D L Cox; J D Radolf
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Microbiology (Reading, England)     Volume:  147     ISSN:  1350-0872     ISO Abbreviation:  Microbiology (Reading, Engl.)     Publication Date:  2001 May 
Date Detail:
Created Date:  2001-04-26     Completed Date:  2001-09-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9430468     Medline TA:  Microbiology     Country:  England    
Other Details:
Languages:  eng     Pagination:  1161-9     Citation Subset:  IM    
The Bacterial STD Branch, Centers for Disease Control and Prevention, Mailstop D-13, 1600 Clifton Rd, Atlanta, GA 30333, USA.
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MeSH Terms
Biological Transport
Borrelia burgdorferi Group / chemistry*,  metabolism
Cell Membrane / chemistry,  metabolism
Cell Membrane Permeability
Escherichia coli / chemistry,  metabolism
Fatty Acids / chemistry*,  metabolism
Flow Cytometry
Fluoresceins / chemistry*
Fluorescent Dyes / chemistry*
Treponema pallidum / chemistry*,  metabolism
Grant Support
Reg. No./Substance:
0/5-(N-octadecanoyl)aminofluorescein; 0/Fatty Acids; 0/Fluoresceins; 0/Fluorescent Dyes; 107827-77-0/5-(N-dodecanoyl)aminofluorescein; 2321-07-5/Fluorescein; 73024-80-3/(hexadecanoyl)aminofluorescein

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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