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A Staphylococcus aureus ypfP mutant with strongly reduced lipoteichoic acid (LTA) content: LTA governs bacterial surface properties and autolysin activity.

Fedtke I, Mader D, Kohler T, Moll H, Nicholson G, Biswas R, Henseler K, Götz F, Zähringer U, Peschel A - Mol. Microbiol. (2007)

Bottom Line: The ypfP gene responsible for biosynthesis of a glycolipid found in LTA was deleted in Staphylococcus aureus SA113, causing 87% reduction of the LTA content.However, the autolytic activity of the mutant was strongly reduced demonstrating a role of LTA in controlling autolysin activity.Moreover, the hydrophobicity of the LTA mutant was altered and its ability to form biofilms on plastic was completely abrogated indicating a profound impact of LTA on physicochemical properties of bacterial surfaces.

View Article: PubMed Central - PubMed

Affiliation: Cellular and Molecular Microbiology Division, University of Tübingen, Department of Medical Microbiology and Hygiene, 72076 Tübingen, Germany.

ABSTRACT
Many Gram-positive bacteria produce lipoteichoic acid (LTA) polymers whose physiological roles have remained a matter of debate because of the lack of LTA-deficient mutants. The ypfP gene responsible for biosynthesis of a glycolipid found in LTA was deleted in Staphylococcus aureus SA113, causing 87% reduction of the LTA content. Mass spectrometry and nuclear magnetic resonance spectroscopy revealed that the mutant LTA contained a diacylglycerol anchor instead of the glycolipid, whereas the remaining part was similar to the wild-type polymer except that it was shorter. The LTA mutant strain revealed no major changes in patterns of cell wall proteins or autolytic enzymes compared with the parental strain indicating that LTA may be less important in S. aureus protein attachment than previously thought. However, the autolytic activity of the mutant was strongly reduced demonstrating a role of LTA in controlling autolysin activity. Moreover, the hydrophobicity of the LTA mutant was altered and its ability to form biofilms on plastic was completely abrogated indicating a profound impact of LTA on physicochemical properties of bacterial surfaces. We propose to consider LTA and its biosynthetic enzymes as targets for new antibiofilm strategies.

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Cell surface hydrophobicity of S. aureus strains. The propensities of S. aureus wild type (wt), ΔypfP::ermB (ΔypfP), ΔypfP::ermB (pRB473ypfP) (ΔypfP compl.) and Δica (Δica) to associate with the organic or aqueous phase in a dodecane/buffer mixture were determined. SA113 strains, grey bars; RN4220 strains, white bars. Data represent the means ± SEM of at least nine counts from three independent experiments (ns, not significant, ***P < 0.0001 versus wild type; unpaired, two-tailed t-test).
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fig08: Cell surface hydrophobicity of S. aureus strains. The propensities of S. aureus wild type (wt), ΔypfP::ermB (ΔypfP), ΔypfP::ermB (pRB473ypfP) (ΔypfP compl.) and Δica (Δica) to associate with the organic or aqueous phase in a dodecane/buffer mixture were determined. SA113 strains, grey bars; RN4220 strains, white bars. Data represent the means ± SEM of at least nine counts from three independent experiments (ns, not significant, ***P < 0.0001 versus wild type; unpaired, two-tailed t-test).

Mentions: Lipoteichoic acid molecules are exposed on the bacterial surface and the high number of charged phosphate and d-Ala residues has probably a considerable impact on the bacterial surface structure. Such physicochemical properties are critical in staphylococcal adherence to artificial surfaces such as catheters or heart valve prostheses and in resulting biofilm-associated infections (Davey and O'Toole, 2000; Götz, 2002). In order to study possible differences in overall surface hydrophobicity SA113 wild-type and ypfP mutant strains were compared for their propensity to associate with aqueous or organic phase after vigorous shaking in a mixture of phosphate buffer and dodecane. As shown in Fig. 8, the ypfP mutant revealed a significant increase in hydrophobicity while the complemented mutant behaved like the wild type. In contrast, RN4220 wild type and ypfP mutant exhibited the same hydrophobicity (Fig. 8) indicating that LTA depletion but not lack of the glycolipid leads to increased hydrophobicity. The previously described SA113 ica mutant (Cramton et al., 1999), which does not produce the slime polymer polysaccharide intercellular adhesin (PIA) needed for cell-to-cell binding within biofilms (Heilmann et al., 1996a), also revealed reduced hydrophobicity although to a lower extent than the SA113 ypfP mutant (Fig. 8).


A Staphylococcus aureus ypfP mutant with strongly reduced lipoteichoic acid (LTA) content: LTA governs bacterial surface properties and autolysin activity.

Fedtke I, Mader D, Kohler T, Moll H, Nicholson G, Biswas R, Henseler K, Götz F, Zähringer U, Peschel A - Mol. Microbiol. (2007)

Cell surface hydrophobicity of S. aureus strains. The propensities of S. aureus wild type (wt), ΔypfP::ermB (ΔypfP), ΔypfP::ermB (pRB473ypfP) (ΔypfP compl.) and Δica (Δica) to associate with the organic or aqueous phase in a dodecane/buffer mixture were determined. SA113 strains, grey bars; RN4220 strains, white bars. Data represent the means ± SEM of at least nine counts from three independent experiments (ns, not significant, ***P < 0.0001 versus wild type; unpaired, two-tailed t-test).
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Related In: Results  -  Collection

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fig08: Cell surface hydrophobicity of S. aureus strains. The propensities of S. aureus wild type (wt), ΔypfP::ermB (ΔypfP), ΔypfP::ermB (pRB473ypfP) (ΔypfP compl.) and Δica (Δica) to associate with the organic or aqueous phase in a dodecane/buffer mixture were determined. SA113 strains, grey bars; RN4220 strains, white bars. Data represent the means ± SEM of at least nine counts from three independent experiments (ns, not significant, ***P < 0.0001 versus wild type; unpaired, two-tailed t-test).
Mentions: Lipoteichoic acid molecules are exposed on the bacterial surface and the high number of charged phosphate and d-Ala residues has probably a considerable impact on the bacterial surface structure. Such physicochemical properties are critical in staphylococcal adherence to artificial surfaces such as catheters or heart valve prostheses and in resulting biofilm-associated infections (Davey and O'Toole, 2000; Götz, 2002). In order to study possible differences in overall surface hydrophobicity SA113 wild-type and ypfP mutant strains were compared for their propensity to associate with aqueous or organic phase after vigorous shaking in a mixture of phosphate buffer and dodecane. As shown in Fig. 8, the ypfP mutant revealed a significant increase in hydrophobicity while the complemented mutant behaved like the wild type. In contrast, RN4220 wild type and ypfP mutant exhibited the same hydrophobicity (Fig. 8) indicating that LTA depletion but not lack of the glycolipid leads to increased hydrophobicity. The previously described SA113 ica mutant (Cramton et al., 1999), which does not produce the slime polymer polysaccharide intercellular adhesin (PIA) needed for cell-to-cell binding within biofilms (Heilmann et al., 1996a), also revealed reduced hydrophobicity although to a lower extent than the SA113 ypfP mutant (Fig. 8).

Bottom Line: The ypfP gene responsible for biosynthesis of a glycolipid found in LTA was deleted in Staphylococcus aureus SA113, causing 87% reduction of the LTA content.However, the autolytic activity of the mutant was strongly reduced demonstrating a role of LTA in controlling autolysin activity.Moreover, the hydrophobicity of the LTA mutant was altered and its ability to form biofilms on plastic was completely abrogated indicating a profound impact of LTA on physicochemical properties of bacterial surfaces.

View Article: PubMed Central - PubMed

Affiliation: Cellular and Molecular Microbiology Division, University of Tübingen, Department of Medical Microbiology and Hygiene, 72076 Tübingen, Germany.

ABSTRACT
Many Gram-positive bacteria produce lipoteichoic acid (LTA) polymers whose physiological roles have remained a matter of debate because of the lack of LTA-deficient mutants. The ypfP gene responsible for biosynthesis of a glycolipid found in LTA was deleted in Staphylococcus aureus SA113, causing 87% reduction of the LTA content. Mass spectrometry and nuclear magnetic resonance spectroscopy revealed that the mutant LTA contained a diacylglycerol anchor instead of the glycolipid, whereas the remaining part was similar to the wild-type polymer except that it was shorter. The LTA mutant strain revealed no major changes in patterns of cell wall proteins or autolytic enzymes compared with the parental strain indicating that LTA may be less important in S. aureus protein attachment than previously thought. However, the autolytic activity of the mutant was strongly reduced demonstrating a role of LTA in controlling autolysin activity. Moreover, the hydrophobicity of the LTA mutant was altered and its ability to form biofilms on plastic was completely abrogated indicating a profound impact of LTA on physicochemical properties of bacterial surfaces. We propose to consider LTA and its biosynthetic enzymes as targets for new antibiofilm strategies.

Show MeSH
Related in: MedlinePlus