Heterogeneity in theM. tuberculosisβ-lactamase inhibition by Sulbactam

AbstractFor decades, researchers have been determined to elucidate essential enzymatic functions on the atomic lengths scale by tracing atomic positions in real time. Our work builds on new possibilities unleashed by mix-and-inject serial crystallography (MISC)1-5at X-ray free electron laser facilities. In this approach, enzymatic reactions are triggered by mixing substrate or ligand solutions with enzyme microcrystals6. Here, we report in atomic detail and with millisecond time-resolution how theMycobacterium tuberculosisenzyme BlaC is inhibited by sulbactam (SUB). Our results reveal ligand binding heterogeneity, ligand gating7-9, cooperativity, induced fit10,11and conformational selection11-13all from the same set of MISC data, detailing how SUB approaches the catalytic clefts and binds to the enzyme non-covalently before reacting to atrans-enamine. This was made possible in part by the application of the singular value decomposition14to the MISC data using a newly developed program that remains functional even if unit cell parameters change during the reaction.