Limits...
Probing BoNT/A protease exosites: implications for inhibitor design and light chain longevity.

Xue S, Javor S, Hixon MS, Janda KD - Biochemistry (2014)

Bottom Line: Studies on BoNT/A LC have revealed that two regions, termed exosites, can play an important role in BoNT catalytic activity.A clear understanding of how these exosites influence neurotoxin catalytic activity would provide a critical framework for deciphering the mechanism of SNAP-25 cleavage and the design of inhibitors.These data help delineate why α-exosite binding is needed for SNAP-25 cleavage and also provide new insights into the extended lifetime observed for BoNT/A LC in vivo.

View Article: PubMed Central - PubMed

Affiliation: Departments of Chemistry and Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States.

ABSTRACT
Botulinum neurotoxin serotype A (BoNT/A) is one of the most lethal toxins known. Its extreme toxicity is due to its light chain (LC), a zinc protease that cleaves SNAP-25, a synaptosome-associated protein, leading to the inhibition of neuronal activity. Studies on BoNT/A LC have revealed that two regions, termed exosites, can play an important role in BoNT catalytic activity. A clear understanding of how these exosites influence neurotoxin catalytic activity would provide a critical framework for deciphering the mechanism of SNAP-25 cleavage and the design of inhibitors. Herein, based on the crystallographic structure of BoNT/A LC complexed with its substrate, we designed an α-exosite binding probe. Experiments with this unique probe demonstrated that α-exosite binding enhanced both catalytic activity and stability of the LC. These data help delineate why α-exosite binding is needed for SNAP-25 cleavage and also provide new insights into the extended lifetime observed for BoNT/A LC in vivo.

Show MeSH

Related in: MedlinePlus

Mechanism of Mutually Exclusive InhibitionI1 and I2 are the concentrationsof two inhibitors; KI1 and KI2 are KI of I1 and I2 separately;S, KM, kcat, and vmax have their usual definitions. As shown in eq 1, atvarious concentrations of I2, curves of 1/v versusI1 have the same slope, giving parallel curves.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4222541&req=5

sch1: Mechanism of Mutually Exclusive InhibitionI1 and I2 are the concentrationsof two inhibitors; KI1 and KI2 are KI of I1 and I2 separately;S, KM, kcat, and vmax have their usual definitions. As shown in eq 1, atvarious concentrations of I2, curves of 1/v versusI1 have the same slope, giving parallel curves.


Probing BoNT/A protease exosites: implications for inhibitor design and light chain longevity.

Xue S, Javor S, Hixon MS, Janda KD - Biochemistry (2014)

Mechanism of Mutually Exclusive InhibitionI1 and I2 are the concentrationsof two inhibitors; KI1 and KI2 are KI of I1 and I2 separately;S, KM, kcat, and vmax have their usual definitions. As shown in eq 1, atvarious concentrations of I2, curves of 1/v versusI1 have the same slope, giving parallel curves.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222541&req=5

sch1: Mechanism of Mutually Exclusive InhibitionI1 and I2 are the concentrationsof two inhibitors; KI1 and KI2 are KI of I1 and I2 separately;S, KM, kcat, and vmax have their usual definitions. As shown in eq 1, atvarious concentrations of I2, curves of 1/v versusI1 have the same slope, giving parallel curves.
Bottom Line: Studies on BoNT/A LC have revealed that two regions, termed exosites, can play an important role in BoNT catalytic activity.A clear understanding of how these exosites influence neurotoxin catalytic activity would provide a critical framework for deciphering the mechanism of SNAP-25 cleavage and the design of inhibitors.These data help delineate why α-exosite binding is needed for SNAP-25 cleavage and also provide new insights into the extended lifetime observed for BoNT/A LC in vivo.

View Article: PubMed Central - PubMed

Affiliation: Departments of Chemistry and Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States.

ABSTRACT
Botulinum neurotoxin serotype A (BoNT/A) is one of the most lethal toxins known. Its extreme toxicity is due to its light chain (LC), a zinc protease that cleaves SNAP-25, a synaptosome-associated protein, leading to the inhibition of neuronal activity. Studies on BoNT/A LC have revealed that two regions, termed exosites, can play an important role in BoNT catalytic activity. A clear understanding of how these exosites influence neurotoxin catalytic activity would provide a critical framework for deciphering the mechanism of SNAP-25 cleavage and the design of inhibitors. Herein, based on the crystallographic structure of BoNT/A LC complexed with its substrate, we designed an α-exosite binding probe. Experiments with this unique probe demonstrated that α-exosite binding enhanced both catalytic activity and stability of the LC. These data help delineate why α-exosite binding is needed for SNAP-25 cleavage and also provide new insights into the extended lifetime observed for BoNT/A LC in vivo.

Show MeSH
Related in: MedlinePlus