8OE5

Structure of P167S BlaC from Mycobacterium tuberculosis at pH 6.3

Summary for 8OE5

• Entry DOI: 10.2210/pdb8oe5/pdb
• Descriptor: Beta-lactamase, GLYCEROL, CITRATE ANION, ... (4 entities in total)
• Functional Keywords: hydrolase
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 2
• Total formula weight: 57087.76

Authors

Sun, J.,Chikunova, A.,Ubbink, M. (deposition date: 2023-03-10, release date: 2023-08-23, Last modification date: 2024-10-09)

Primary citation

Sun, J.,Chikunova, A.,Boyle, A.L.,Voskamp, P.,Timmer, M.,Ubbink, M.
Enhanced activity against a third-generation cephalosporin by destabilization of the active site of a class A beta-lactamase.
Int.J.Biol.Macromol., 250:126160-126160, 2023

PubMed Abstract: The β-lactamase BlaC conveys resistance to a broad spectrum of β-lactam antibiotics to its host Mycobacterium tuberculosis but poorly hydrolyzes third-generation cephalosporins, such as ceftazidime. Variants of other β-lactamases have been reported to gain activity against ceftazidime at the cost of the native activity. To understand this trade-off, laboratory evolution was performed, screening for enhanced ceftazidime activity. The variant BlaC Pro167Ser shows faster breakdown of ceftazidime, poor hydrolysis of ampicillin and only moderately reduced activity against nitrocefin. NMR spectroscopy, crystallography and kinetic assays demonstrate that the resting state of BlaC P167S exists in an open and a closed state. The open state is more active in the hydrolysis of ceftazidime. In this state the catalytic residue Glu166, generally believed to be involved in the activation of the water molecule required for deacylation, is rotated away from the active site, suggesting it plays no role in the hydrolysis of ceftazidime. In the closed state, deacylation of the BlaC-ceftazidime adduct is slow, while hydrolysis of nitrocefin, which requires the presence of Glu166 in the active site, is barely affected, providing a structural explanation for the trade-off in activities.

PubMed: 37549761
DOI: 10.1016/j.ijbiomac.2023.126160

Experimental method

X-RAY DIFFRACTION (1.8 Å)