A structural comparison of inhibitor binding to PKB, PKA and PKA-PKB chimera.
Although the crystal structure of the anti-cancer target protein kinase B (PKBbeta/Akt-2) has been useful in guiding inhibitor design, the closely related kinase PKA has generally been used as a structural mimic due to its facile crystallization with a range of ligands. The use of PKB-inhibitor crystallography would bring important benefits, including a more rigorous understanding of factors dictating PKA/PKB selectivity, and the opportunity to validate the utility of PKA-based surrogates. We present a "back-soaking" method for obtaining PKBbeta-ligand crystal structures, and provide a structural comparison of inhibitor binding to PKB, PKA, and PKA-PKB chimera. One inhibitor presented here exhibits no PKB/PKA selectivity, and the compound adopts a similar binding mode in all three systems. By contrast, the PKB-selective inhibitor A-443654 adopts a conformation in PKB and PKA-PKB that differs from that with PKA. We provide a structural explanation for this difference, and highlight the ability of PKA-PKB to mimic the true PKB binding mode in this case.
Davies
Thomas G
TG
Astex Therapeutics Ltd, 436 Cambridge Science Park, Milton Road, Cambridge, CB4 0QA, UK. t.davies@astex-therapeutics.com
Verdonk
Marcel L
ML
Graham
Brent
B
Saalau-Bethell
Susanne
S
Hamlett
Christopher C F
CC
McHardy
Tatiana
T
Collins
Ian
I
Garrett
Michelle D
MD
Workman
Paul
P
Woodhead
Steven J
SJ
Jhoti
Harren
H
Barford
David
D
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D018360:Crystallography, X-Ray; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D011487:Protein Conformation; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity
D011993:Recombinant Fusion Proteins; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases