β-Lactamases are enzymes that can break down β-lactam substrates, such as antibiotics, preventing the use of these antibiotics for the treatment of various infectious diseases. However, some compounds, β-lactamase inhibitors, can block these enzymes allowing for possible treatments using a combination of antibiotic and inhibitor. BlaC is the β-lactamase of Mycobacterium tuberculosis, the bacteria that cause tuberculosis, and is used as a model for protein evolution.
To understand if and how BlaC can develop resistance against certain inhibitors we studied the evolutionary adaptability of this enzyme. We used laboratory evolution and various biochemical techniques to characterize several mutations in BlaC and subsequently tested the effect of combining mutations. One of the findings is that BlaC can easily become less sensitive to the inhibitor sulbactam by partially blocking the entrance to the active site. Interestingly, this was accompanied by increased sensitivity...
Show moreβ-Lactamases are enzymes that can break down β-lactam substrates, such as antibiotics, preventing the use of these antibiotics for the treatment of various infectious diseases. However, some compounds, β-lactamase inhibitors, can block these enzymes allowing for possible treatments using a combination of antibiotic and inhibitor. BlaC is the β-lactamase of Mycobacterium tuberculosis, the bacteria that cause tuberculosis, and is used as a model for protein evolution.
To understand if and how BlaC can develop resistance against certain inhibitors we studied the evolutionary adaptability of this enzyme. We used laboratory evolution and various biochemical techniques to characterize several mutations in BlaC and subsequently tested the effect of combining mutations. One of the findings is that BlaC can easily become less sensitive to the inhibitor sulbactam by partially blocking the entrance to the active site. Interestingly, this was accompanied by increased sensitivity to another inhibitor, avibactam, that could not be compensated for by other mutations.
Generally, Escherichia coli bacteria are used to test the effects of BlaC variants in cells, as they are easy and safe to use in the lab. We show that results obtained for E. coli can be extrapolated to conditions that resemble tuberculosis disease in humans: the M. marinum infection model of zebrafish. All these findings are of interest for the future development of combination therapies to treat tuberculosis.
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