Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 113, Issue 26, Pages E3686-E3695Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1606472113
Keywords
phosphoinositide; Dr-VSP; Ci-VSP; PI(3,4,5)P-3; PI(4,5)P-2
Categories
Funding
- National Institute of Neurological Disorders and Stroke of the NIH [R37NS008174]
- Wayne E. Crill Endowed Professorship
- Korean Brain Research Institute basic research program - Ministry of Science, Information and Communications Technology and Future Planning [2231-415]
- Daegu Gyeongbuk Institute of Science and Technology (DGIST) RAMP
- D Program of the Ministry of Science, Information and Communications Technology AMP
- Future Planning [16-BD-06]
- NIH from the National Institute of General Medical Sciences [P41GM103313]
Ask authors/readers for more resources
Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P-2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P-3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P-2 and probably PI(3,4,5)P-3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P-2] and PI(3,4,5)P-3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence. Using Forster resonance energy transfer probes specific for different PIs in living cells with zebrafish VSP, we quantitate both voltage-dependent 5- and 3-phosphatase subreactions against endogenous substrates. These activities become apparent with different voltage thresholds, voltage sensitivities, and catalytic rates. As an analytical tool, we refine a kinetic model that includes the endogenous pools of phosphoinositides, endogenous phosphatase and kinase reactions connecting them, and four exogenous voltage-dependent 5-and 3-phosphatase subreactions of VSP. We show that apparent voltage threshold differences for seeing effects of the 5-and 3-phosphatase activities in cells are not due to different intrinsic voltage dependence of these reactions. Rather, the reactions have a common voltage dependence, and apparent differences arise only because each VSP subreaction has a different absolute catalytic rate that begins to surpass the respective endogenous enzyme activities at different voltages. For zebrafish VSP, our modeling revealed that 3-phosphatase activity against PI(3,4,5)P-3 is 55-fold slower than 5-phosphatase activity against PI(4,5)P-2; thus, PI(4,5)P-2 generated more slowly from dephosphorylating PI(3,4,5)P-3 might never accumulate. When 5-phosphatase activity was counteracted by coexpression of a phosphatidylinositol 4-phosphate 5-kinase, there was accumulation of PI(4,5)P-2 in parallel to PI(3,4,5)P-3 dephosphorylation, emphasizing that VSPs can cleave the 3-phosphate of PI(3,4,5)P-3.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available