TY - JOUR
T1 - Irreversible inhibition of the Mycobacterium tuberculosis β-lactamase by clavulanate
AU - Hugonnet, Jean Emmanuel
AU - Blanchard, John S.
PY - 2007/10/30
Y1 - 2007/10/30
N2 - Members of the β-lactam class of antibiotics, which inhibit the bacterial D,D-transpeptidases involved in cell wall biosynthesis, have never been used systematically in the treatment of Mycobacterium tuberculosis infections because of this organism's resistance to β-lactams. The critical resistance factor is the constitutive production of a chromosomally encoded, Ambler class A β-lactamase, BlaC in M. tuberculosis. We show that BlaC is an extended spectrum β-lactamase (ESBL) with high levels of penicillinase and cephalosporinase activity as well as measurable activity with carbapenems, including imipenem and meropenem. We have characterized the enzyme's inhibition by three FDA-approved β-lactamase inhibitors: sulbactam, tazobactam, and clavulanate. Sulbactam inhibits the enzyme competitively and reversibly with respect to nitrocefin. Tazobactam inhibits the enzyme in a time-dependent manner, but the activity of the enzyme reappears due to the slow hydrolysis of the covalently acylated enzyme. In contrast, clavulanate reacts with the enzyme quickly to form hydrolytically stable, inactive forms of the enzyme that have been characterized by mass spectrometry. Clavulanate has potential to be used in combination with approved β-lactam antibiotics to treat multi-drug resistant (MDR) and extremely drug resistant (XDR) strains of M. tuberculosis.
AB - Members of the β-lactam class of antibiotics, which inhibit the bacterial D,D-transpeptidases involved in cell wall biosynthesis, have never been used systematically in the treatment of Mycobacterium tuberculosis infections because of this organism's resistance to β-lactams. The critical resistance factor is the constitutive production of a chromosomally encoded, Ambler class A β-lactamase, BlaC in M. tuberculosis. We show that BlaC is an extended spectrum β-lactamase (ESBL) with high levels of penicillinase and cephalosporinase activity as well as measurable activity with carbapenems, including imipenem and meropenem. We have characterized the enzyme's inhibition by three FDA-approved β-lactamase inhibitors: sulbactam, tazobactam, and clavulanate. Sulbactam inhibits the enzyme competitively and reversibly with respect to nitrocefin. Tazobactam inhibits the enzyme in a time-dependent manner, but the activity of the enzyme reappears due to the slow hydrolysis of the covalently acylated enzyme. In contrast, clavulanate reacts with the enzyme quickly to form hydrolytically stable, inactive forms of the enzyme that have been characterized by mass spectrometry. Clavulanate has potential to be used in combination with approved β-lactam antibiotics to treat multi-drug resistant (MDR) and extremely drug resistant (XDR) strains of M. tuberculosis.
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U2 - 10.1021/bi701506h
DO - 10.1021/bi701506h
M3 - Article
C2 - 17915954
AN - SCOPUS:35649007240
SN - 0006-2960
VL - 46
SP - 11998
EP - 12004
JO - Biochemistry
JF - Biochemistry
IS - 43
ER -