Characterization of Peptidoglycan in Fem-Deletion Mutants of Methicillin-Resistant Staphylococcus aureus by Solid-State NMR†

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• 作者：Shasad Sharif^‡ ; ; Sung Joon Kim^‡ ; ; Harald Labischinski^§ ; ; Jacob Schaefer*^‡ ;
• 刊名：Biochemistry
• 出版年：2009
• 出版时间：April 14, 2009
• 年：2009
• 卷：48
• 期：14
• 页码：3100-3108
• 全文大小：263K
• 年卷期：v.48,no.14(April 14, 2009)
• ISSN：1520-4995

文摘

Compositional analysis of the peptidoglycan (PG) of a wild-type methicillin-resistant Staphylococcus aureus and its fem-deletion mutants has been performed on whole cells and cell walls using stable-isotope labeling and rotational-echo double-resonance NMR. The labels included [1-¹³C,¹⁵N]glycine and l-[ε-¹⁵N]lysine (for a direct measure of the number of glycyl residues in the bridging segment), [1-¹³C]glycine and l-[ε-¹⁵N]lysine (concentration of bridge links), and d-[1-¹³C]alanine and [¹⁵N]glycine (concentrations of cross-links and wall teichoic acids). The bridging segment length changed from 5.0 glycyl residues (wild-type strain) to 2.5 ± 0.1 (FemB) with modest changes in cross-link and bridge-link concentrations. This accurate in situ measurement for the FemB mutant indicates a heterogeneous PG structure with 25% monoglycyl and 75% triglycyl bridges. When the bridging segment was reduced to a single glycyl residue 1.0 ± 0.1 (FemA), the level of cross-linking decreased by more than 20%, resulting in a high concentration of open N-terminal glycyl segments.