Crystallographic snapshots of ligand binding to hexameric purine nucleoside phosphorylase and kinetic studies give insight into the mechanism of catalysis
PBN-AR
Instytucja
Wydział Fizyki (Uniwersytet Warszawski)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
SCIENTIFIC REPORTS OF THE NATURE PUBLISHING GROUP (40pkt w roku publikacji)
ISSN
2045-2322
EISSN
Wydawca
DOI
URL
Rok publikacji
2018
Numer zeszytu
1
Strony od-do
15427
Numer tomu
8
Identyfikator DOI
Liczba arkuszy
Streszczenia
Język
en
Treść
Purine nucleoside phosphorylase (PNP) catalyses the cleavage of the glycosidic bond of purine nucleosides using phosphate instead of water as a second substrate. PNP from Escherichia coli is a homohexamer, build as a trimer of dimers, and each subunit can be in two conformations, open or closed. This conformational change is induced by the presence of phosphate substrate, and very likely a required step for the catalysis. Closing one active site strongly affects the others, by a yet unclear mechanism and order of events. Kinetic and ligand binding studies show strong negative cooperativity between subunits. Here, for the first time, we managed to monitor the sequence of nucleoside binding to individual subunits in the crystal structures of the wild-type enzyme, showing that first the closed sites, not the open ones, are occupied by the nucleoside. However, two mutations within the active site, Asp204Ala/Arg217Ala, are enough not only to significantly reduce the effectiveness of the enzyme, but also reverse the sequence of the nucleoside binding. In the mutant the open sites, neighbours in a dimer of those in the closed conformation, are occupied as first. This demonstrates how important for the effective catalysis of Escherichia coli PNP is proper subunit cooperation.
Cechy publikacji
discipline:Biofizyka – dziedzina nauk fizycznych
discipline:Biophysics – field of physical sciences
Original article
Original article presents the results of original research or experiment.
Oryginalny artykuł naukowy
Oryginalny artykuł naukowy przedstawia rezultaty oryginalnych badań naukowych lub eksperymentu.
Inne
System-identifier
PBN-R:895690
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