The differential regulation of phosphatidylinositol 4-phosphate 5-kinases and phospholipase D1 by ADP-ribosylation factors 1 and 6.
Phosphatidylinositol 4-phosphate 5-kinases [PtdIns4P5Ks] synthesise the majority of cellular phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] and phospholipase D1 (PLD1) synthesises large amounts of phosphatidic acid (PtdOH). The activities of PtdIns4P5Ks and PLDs are thought to be coupled during cell signalling in order to support large simultaneous increases in both PtdIns(4,5)P(2) and PtdOH, since PtdOH activates PtdIns4P5Ks and PLD1 requires PtdIns(4,5)P(2) as a cofactor. However, little is known about the control of such a system. Membrane recruitment of ADP-ribosylation factors (Arfs) activates both PtdIns4P5Ks and PLDs, but it is not known if each enzyme is controlled in series by different Arfs or in parallel by a single form. We show through pull-down and vesicle sedimentation interaction assays that PtdIns4P5K activation may be facilitated by Arf-enhanced membrane association. However PtdIns4P5Ks discriminate poorly between near homogeneously myristoylated Arf1 and Arf6 although examples of all three known active isoforms (mouse alpha>beta, gamma) respond to these G-proteins. Conversely PLD1 genuinely prefers Arf1 and so the two lipid metabolising enzymes are differentially controlled. We propose that isoform selective Arf/PLD interaction and not Arf/PtdIns4P5K will be the critical trigger in the formation of distinct, optimal triples of Arf/PLDs/PtdIns4P5Ks and be the principle regulator of any coupled increases in the signalling lipids PtdIns(4,5)P(2) and PtdOH.
Perez-Mansilla
Borja
B
Department of Physiology, University College London, Rockefeller Building, 21 University Street, London WC1E 6JJ, UK.
Ha
Vi Luan
VL
Justin
Neil
N
Wilkins
Andrew J
AJ
Carpenter
Christopher L
CL
Thomas
Geraint M H
GM
D020823:ADP-Ribosylation Factor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002474:Cell-Free System; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D006160:Guanosine Triphosphate / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008563:Membrane Lipids / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D009227:Myristic Acids / Q000737:chemistry; D010739:Phospholipase D / Q000235:genetics / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D000089982:ADP-Ribosylation Factor 6; D017931:DNA Primers; D008563:Membrane Lipids; D009227:Myristic Acids; D010743:Phospholipids; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D010739:Phospholipase D; C106801:phospholipase D1; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; C000715727:Arf6 protein, mouse