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Characterization of Gain-of-function Mutant Provides New Insights into ClpP Mechanism of Activation
Update time: 2016-07-11
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Nowadays, the conventional antibiotics usually fail to cure chronic bacterial infection owing to antibiotic sensitive bacterial pathogens in a dormant state. These dormant bacteria called "persisters" do not display any characteristics of life in addition to waiting for re-infection. It remains a big challenge to treat deep-seated persisters in clinic.

The ATP-dependent Clp protease (ClpP) plays an essential role in the control of protein quality and in the regulation of bacterial virulence. Acyldepsipeptides (ADEPs) have been identified as a new class of antibiotics that activate ClpP in dysfunctional state. ADEP in combination with rifampicin eradicates a deep-seated persister. These findings indicate a general principle for killing dormant cells—activation and corruption of a target, rather than conventional inhibition. Prof. YANG Caiguang’s group and others have extensively characterized the structural mechanism and molecular dynamics of the ClpP protease of Staphylococcus aureus. However, how the structural dynamics of activation ClpP are regulated remains unclear.

In order to address how ClpP could be converted into a non-controllable enzyme capable of degrading mature proteins in the presence of ADEPs, Prof. Yang’s group predicted that certain mutations will convert ClpP into a non-controllable enzyme capable of degrading mature proteins, as happens in the presence of ADEPs. Indeed, they have succeeded in designing such gain-of-function mutants and show that the protease is now active in the absence of activators. Furthermore, the engineering of an allele of the clpP gene in S. aureus that encodes a peptidase have dysregulated catalytic activity. This allele is of interest because it causes a phenotype that is reminiscent of observations made upon the treatment of wild-type S. aureus strain with ADEPs that dysregulate the catalytic activity of ClpP. They also showed that the bacterial cells expressing the mutant ClpP can now be readily eradicated by conventional antibiotics. Taken together, the researchers concluded that this substitution has a “domino effect” that reorients several adjacent residues such that an open-gate conformation can be reached. The finding has been published in ACS Chem. Biol. on May 12, 2016.

The study was supported by the collaborative researches from Zhejiang Sci-tech University, Shanghai Synchrotron Radiation Facility, National Center for Protein Science, Shanghai University of Traditional Chinese Medicine, Fudan University, and Shanghai Institute of Materia Medica, and was partially funded by the National Natural Science Foundation of China and Shanghai Institute of Materia Medica.





The engineering and characterization of an allele of the clpP gene in S. aureus that encodes a peptidase having dysregulated catalytic activity(Image by SIMM)

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