Benzene polyphosphates as tools for cell signalling: inhibition of inositol 1,4,5-trisphosphate 5-phosphatase and interaction with the PH domain of protein kinase Balpha.
Novel benzene polyphosphates were synthesised as inositol polyphosphate mimics and evaluated against type-I inositol 1,4,5-trisphosphate 5-phosphatase, which only binds soluble inositol polyphosphates, and against the PH domain of protein kinase Balpha (PKBalpha), which can bind both soluble inositol polyphosphates and inositol phospholipids. The most potent trisphosphate 5-phosphatase inhibitor is benzene 1,2,4-trisphosphate (2, IC(50) of 14 microM), a potential mimic of D-myo-inositol 1,4,5-trisphosphate, whereas the most potent tetrakisphosphate Ins(1,4,5)P(3) 5-phosphatase inhibitor is benzene 1,2,4,5-tetrakisphosphate, with an IC(50) of 4 microM. Biphenyl 2,3',4,5',6-pentakisphosphate (4) was the most potent inhibitor evaluated against type I Ins(1,4,5)P(3) 5-phosphatase (IC(50) of 1 microM). All new benzene polyphosphates are resistant to dephosphorylation by type I Ins(1,4,5)P(3) 5-phosphatase. Unexpectedly, all benzene polyphosphates studied bind to the PH domain of PKBalpha with apparent higher affinity than to type I Ins(1,4,5)P(3) 5-phosphatase. The most potent ligand for the PKBalpha PH domain, measured by inhibition of biotinylated diC(8)-PtdIns(3,4)P(2) binding, is biphenyl 2,3',4,5',6-pentakisphosphate (4, K(i)=27 nm). The approximately 80-fold enhancement of binding relative to parent benzene trisphosphate is explained by the involvement of a cation-pi interaction. These new molecular tools will be of potential use in structural and cell signalling studies.
Wolfson Laboratory of Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA27AY, UK.
Stephen J
SJ
Mills
Fabrice
F
Vandeput
Melanie N
MN
Trusselle
Stephen T
ST
Safrany
Christophe
C
Erneux
Barry V L
BV
Potter
D001554:Benzene / Q000737:chemistry*; D001665:Binding Sites; D031541:Fluorescence Resonance Energy Transfer; D000072181:Inositol Polyphosphate 5-Phosphatases; D008024:Ligands; D008958:Models, Molecular; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011122:Polyphosphates / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D008024:Ligands; D011122:Polyphosphates; D051057:Proto-Oncogene Proteins c-akt; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D001554:Benzene