A mecillinam-sensitive peptidoglycan crosslinking reaction in Escherichia coli |
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Authors: | F Ishino S Tamaki B G Spratt M Matsuhashi |
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Institution: | 1. Institute of Applied Microbiology, University of Tokyo, Bunkyo-ku, Tokyo, Japan;7. Microbial Genetics Group, School of Biological Sciences, University of Sussex, Falmer, Sussex, BN1 9QG, U.K. |
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Abstract: | The amidinopenicillin, mecillinam, induces the formation of spherical cells of Escherichia coli by inactivation of penicillin-binding protein 2 (PBP2). A mecillinam-sensitive peptidoglycan crosslinking reaction has been demonstrated in particulate membrane preparations from this organism. The activity was detected in membranes that contained elevated levels of PBP2 and in which crosslinking reactions due to all other PBPs had been inactivated with the cephamycin antibiotic, cefmetazole. The particulate membrane preparation catalyzed synthesis of peptidoglycan that was up to 20% crosslinked from nucleotide precursors. Crosslinkage of the peptidoglycan was inhibited 50% by 0.2 μg mecillinam per ml but was not inhibited by much higher concentrations of cephamycins, which have very low affinity for PBP2. The crosslinking reaction appears to be due to the transpeptidase activity of PBP2, which is implicated in the mechanism of cell shape determination, and is the killing target for mecillinam. |
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Keywords: | meso-2 6-diaminopimelic acid GlcNAc N-acetylglucosamine MurNAc N-acetylmuramic acid PBP penicillin-binding protein |
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