Structural highlights
Function
[VIP2_HUMAN] Bifunctional inositol kinase that acts in concert with the IP6K kinases IP6K1, IP6K2 and IP6K3 to synthesize the diphosphate group-containing inositol pyrophosphates diphosphoinositol pentakisphosphate, PP-InsP5, and bis-diphosphoinositol tetrakisphosphate, (PP)2-InsP4. PP-InsP5 and (PP)2-InsP4, also respectively called InsP7 and InsP8, regulate a variety of cellular processes, including apoptosis, vesicle trafficking, cytoskeletal dynamics, exocytosis, insulin signaling and neutrophil activation. Phosphorylates inositol hexakisphosphate (InsP6) at positions 1 or 3 to produce PP-InsP5 which is in turn phosphorylated by IP6Ks to produce (PP)2-InsP4. Alternatively, phosphorylates at position 1 or 3 PP-InsP5, produced by IP6Ks from InsP6, to produce (PP)2-InsP4.[1] [2]
Publication Abstract from PubMed
The inositol pyrophosphate messengers (PP-InsPs) are emerging as an important class of cellular regulators. These molecules have been linked to numerous biological processes, including insulin secretion and cancer cell migration, but how they trigger such a wide range of cellular responses has remained unanswered in many cases. Here, we show that the PP-InsPs exhibit complex speciation behaviour and propose that a unique conformational switching mechanism could contribute to their multifunctional effects. We synthesised non-hydrolysable bisphosphonate analogues and crystallised the analogues in complex with mammalian PPIP5K2 kinase. Subsequently, the bisphosphonate analogues were used to investigate the protonation sequence, metal-coordination properties, and conformation in solution. Remarkably, the presence of potassium and magnesium ions enabled the analogues to adopt two different conformations near physiological pH. Understanding how the intrinsic chemical properties of the PP-InsPs can contribute to their complex signalling outputs will be essential to elucidate their regulatory functions.
Cellular Cations Control Conformational Switching of Inositol Pyrophosphate Analogues.,Hager A, Wu M, Wang H, Brown NW Jr, Shears SB, Veiga N, Fiedler D Chemistry. 2016 Jul 27. doi: 10.1002/chem.201601754. PMID:27460418[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Fridy PC, Otto JC, Dollins DE, York JD. Cloning and characterization of two human VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinases. J Biol Chem. 2007 Oct 19;282(42):30754-62. Epub 2007 Aug 9. PMID:17690096 doi:http://dx.doi.org/M704656200
- ↑ Choi JH, Williams J, Cho J, Falck JR, Shears SB. Purification, sequencing, and molecular identification of a mammalian PP-InsP5 kinase that is activated when cells are exposed to hyperosmotic stress. J Biol Chem. 2007 Oct 19;282(42):30763-75. Epub 2007 Aug 16. PMID:17702752 doi:http://dx.doi.org/M704655200
- ↑ Hager A, Wu M, Wang H, Brown NW Jr, Shears SB, Veiga N, Fiedler D. Cellular Cations Control Conformational Switching of Inositol Pyrophosphate Analogues. Chemistry. 2016 Jul 27. doi: 10.1002/chem.201601754. PMID:27460418 doi:http://dx.doi.org/10.1002/chem.201601754
