The interdomain loop modulates conformational dynamics for the antibiotic-resistant activity of TEM-type extended-spectrum β-lactamases.

Extended-spectrum β-lactamases (ESBLs) are bacteria-produced enzymes that can hydrolyze and confer extra resistance to new generation β-lactam antibiotics. TEM-type ESBLs are clinically prevalent and have caused serious health problems worldwide. TEM-type ESBLs are the evolutionary products of wild-type TEM-1 β-lactamase mainly through individual or combined mutations of G238S, E104K and M182T, but how these mutations cause conformational dynamics changes of the enzymes and how these changes correlate to their extended-spectrum antibiotic resistance remain unclear. Using hydrogen/deuterium exchange mass spectrometry integrated with molecular dynamics simulation, we revealed the significant effects of these individual or combined mutations on the conformational dynamics of the all-α-domain, α/β-domain and interdomain loop of the enzymes. Particularly, we observed different conformational dynamics changes of the interdomain loop in response to different mutations and substrate binding, which indicated the important role of the interdomain loop in modulating conformational dynamics of ESBLs for the catalytic efficiency. These new findings shed new insights into the antibiotic-resistance mechanism of TEM-type ESBLs and designing of novel inhibitors, and provide clues for the evolutionary strategy of β-lactamases and the studies of proteins with similar linking loops.