Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity

Pei Jung Lu, Woan Ru Shieh, Sue Goo Rhee, Helen L. Yin, Ching Shih Chen

Research output: Contribution to journalArticle

113 Citations (Scopus)

Abstract

To gain insight into the physiological function of phosphoinositide 3- kinase (PI 3-kinase) lipid products, this study examines the interactions of the D-3 phosphoinositides with profilin and the consequent effects on actin dynamics and phosphoinositide turnover. Profilin, a ubiquitous actin- regulating protein, plays a putative role in regulating actin assembly and PLC-γ1 signaling in light of its unique interactions with actin and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. Here we raise evidence that the affinity of profilin with the D-3 phosphoinositides is substantially higher than that of PtdIns(4,5)P2. The dissociation constants (K(d)) are estimated to be 1.1 μM, 5.7 μM, and 11 μM for phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P2], phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3], and PtdIns(4,5)P2, respectively. Spectroscopic data show that while all these phosphoinositides alter the tryptophan fluorescence of profilin in a similar fashion, the respective conformational effect on profilin is vastly different. Based on CD data, the α-helical contents of profilin in the presence of 8 molar equiv of PtdIns(4,5)P2, PtdIns(3,4,5)P3, and PtdIns(3,4)P2 are 17.4%, 11.5%, and 1.4%, respectively, vis-a-vis 9.4% for profilin alone. In contrast, no appreciable change in the fluorescence and CD spectra is observed when related inositol phosphates such as Ins(1,4,5)P3, Ins(1,3,4,5)P4, or Ins(1,3,4)P3 at comparable concentrations are tested. Evidence suggests that this differential recognition bears functional significance concerning the intricate roles of profilin and inositol lipids in modulating actin polymerization and PtdIns(4,5)P2 turnover. The relative potency of individual phosphoinositides in offsetting the inhibitory effect of profilin on actin assembly is PtdIns(3,4)P2 > PtdIns(3,4,5)P3 > PtdIns(4,5)P2, consistent with their relative binding affinity with profilin. Moreover, the inhibitory effect of profilin on PLC-γ1-mediated PtdIns(4,5)P2 hydrolysis is overcome by PtdIns(3,4)P2 and PtdIns(3,4,5)P3 through a combined effect of PLC-γI activation and preferential profilin binding. This D-3 phosphoinositide-mediated regulation may represent a new mechanism for controlling PtdIns(4,5)P2 turnover by PLC-γI.

Original languageEnglish (US)
Pages (from-to)14027-14034
Number of pages8
JournalBiochemistry
Volume35
Issue number44
DOIs
StatePublished - 1996

Fingerprint

Profilins
1-Phosphatidylinositol 4-Kinase
Phosphatidylinositols
Phosphatidylinositol 4,5-Diphosphate
Phosphotransferases
Lipids
Actins
Programmable logic controllers
Fluorescence
Inositol Phosphates
Inositol
Tryptophan
Polymerization

ASJC Scopus subject areas

  • Biochemistry

Cite this

Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity. / Lu, Pei Jung; Shieh, Woan Ru; Rhee, Sue Goo; Yin, Helen L.; Chen, Ching Shih.

In: Biochemistry, Vol. 35, No. 44, 1996, p. 14027-14034.

Research output: Contribution to journalArticle

Lu, Pei Jung ; Shieh, Woan Ru ; Rhee, Sue Goo ; Yin, Helen L. ; Chen, Ching Shih. / Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity. In: Biochemistry. 1996 ; Vol. 35, No. 44. pp. 14027-14034.
@article{4cc01c70b8144512b316a70cf7c2e69b,
title = "Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity",
abstract = "To gain insight into the physiological function of phosphoinositide 3- kinase (PI 3-kinase) lipid products, this study examines the interactions of the D-3 phosphoinositides with profilin and the consequent effects on actin dynamics and phosphoinositide turnover. Profilin, a ubiquitous actin- regulating protein, plays a putative role in regulating actin assembly and PLC-γ1 signaling in light of its unique interactions with actin and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. Here we raise evidence that the affinity of profilin with the D-3 phosphoinositides is substantially higher than that of PtdIns(4,5)P2. The dissociation constants (K(d)) are estimated to be 1.1 μM, 5.7 μM, and 11 μM for phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P2], phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3], and PtdIns(4,5)P2, respectively. Spectroscopic data show that while all these phosphoinositides alter the tryptophan fluorescence of profilin in a similar fashion, the respective conformational effect on profilin is vastly different. Based on CD data, the α-helical contents of profilin in the presence of 8 molar equiv of PtdIns(4,5)P2, PtdIns(3,4,5)P3, and PtdIns(3,4)P2 are 17.4{\%}, 11.5{\%}, and 1.4{\%}, respectively, vis-a-vis 9.4{\%} for profilin alone. In contrast, no appreciable change in the fluorescence and CD spectra is observed when related inositol phosphates such as Ins(1,4,5)P3, Ins(1,3,4,5)P4, or Ins(1,3,4)P3 at comparable concentrations are tested. Evidence suggests that this differential recognition bears functional significance concerning the intricate roles of profilin and inositol lipids in modulating actin polymerization and PtdIns(4,5)P2 turnover. The relative potency of individual phosphoinositides in offsetting the inhibitory effect of profilin on actin assembly is PtdIns(3,4)P2 > PtdIns(3,4,5)P3 > PtdIns(4,5)P2, consistent with their relative binding affinity with profilin. Moreover, the inhibitory effect of profilin on PLC-γ1-mediated PtdIns(4,5)P2 hydrolysis is overcome by PtdIns(3,4)P2 and PtdIns(3,4,5)P3 through a combined effect of PLC-γI activation and preferential profilin binding. This D-3 phosphoinositide-mediated regulation may represent a new mechanism for controlling PtdIns(4,5)P2 turnover by PLC-γI.",
author = "Lu, {Pei Jung} and Shieh, {Woan Ru} and Rhee, {Sue Goo} and Yin, {Helen L.} and Chen, {Ching Shih}",
year = "1996",
doi = "10.1021/bi961878z",
language = "English (US)",
volume = "35",
pages = "14027--14034",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "44",

}

TY - JOUR

T1 - Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity

AU - Lu, Pei Jung

AU - Shieh, Woan Ru

AU - Rhee, Sue Goo

AU - Yin, Helen L.

AU - Chen, Ching Shih

PY - 1996

Y1 - 1996

N2 - To gain insight into the physiological function of phosphoinositide 3- kinase (PI 3-kinase) lipid products, this study examines the interactions of the D-3 phosphoinositides with profilin and the consequent effects on actin dynamics and phosphoinositide turnover. Profilin, a ubiquitous actin- regulating protein, plays a putative role in regulating actin assembly and PLC-γ1 signaling in light of its unique interactions with actin and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. Here we raise evidence that the affinity of profilin with the D-3 phosphoinositides is substantially higher than that of PtdIns(4,5)P2. The dissociation constants (K(d)) are estimated to be 1.1 μM, 5.7 μM, and 11 μM for phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P2], phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3], and PtdIns(4,5)P2, respectively. Spectroscopic data show that while all these phosphoinositides alter the tryptophan fluorescence of profilin in a similar fashion, the respective conformational effect on profilin is vastly different. Based on CD data, the α-helical contents of profilin in the presence of 8 molar equiv of PtdIns(4,5)P2, PtdIns(3,4,5)P3, and PtdIns(3,4)P2 are 17.4%, 11.5%, and 1.4%, respectively, vis-a-vis 9.4% for profilin alone. In contrast, no appreciable change in the fluorescence and CD spectra is observed when related inositol phosphates such as Ins(1,4,5)P3, Ins(1,3,4,5)P4, or Ins(1,3,4)P3 at comparable concentrations are tested. Evidence suggests that this differential recognition bears functional significance concerning the intricate roles of profilin and inositol lipids in modulating actin polymerization and PtdIns(4,5)P2 turnover. The relative potency of individual phosphoinositides in offsetting the inhibitory effect of profilin on actin assembly is PtdIns(3,4)P2 > PtdIns(3,4,5)P3 > PtdIns(4,5)P2, consistent with their relative binding affinity with profilin. Moreover, the inhibitory effect of profilin on PLC-γ1-mediated PtdIns(4,5)P2 hydrolysis is overcome by PtdIns(3,4)P2 and PtdIns(3,4,5)P3 through a combined effect of PLC-γI activation and preferential profilin binding. This D-3 phosphoinositide-mediated regulation may represent a new mechanism for controlling PtdIns(4,5)P2 turnover by PLC-γI.

AB - To gain insight into the physiological function of phosphoinositide 3- kinase (PI 3-kinase) lipid products, this study examines the interactions of the D-3 phosphoinositides with profilin and the consequent effects on actin dynamics and phosphoinositide turnover. Profilin, a ubiquitous actin- regulating protein, plays a putative role in regulating actin assembly and PLC-γ1 signaling in light of its unique interactions with actin and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. Here we raise evidence that the affinity of profilin with the D-3 phosphoinositides is substantially higher than that of PtdIns(4,5)P2. The dissociation constants (K(d)) are estimated to be 1.1 μM, 5.7 μM, and 11 μM for phosphatidylinositol 3,4-bisphosphate [PtdIns(3,4)P2], phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3], and PtdIns(4,5)P2, respectively. Spectroscopic data show that while all these phosphoinositides alter the tryptophan fluorescence of profilin in a similar fashion, the respective conformational effect on profilin is vastly different. Based on CD data, the α-helical contents of profilin in the presence of 8 molar equiv of PtdIns(4,5)P2, PtdIns(3,4,5)P3, and PtdIns(3,4)P2 are 17.4%, 11.5%, and 1.4%, respectively, vis-a-vis 9.4% for profilin alone. In contrast, no appreciable change in the fluorescence and CD spectra is observed when related inositol phosphates such as Ins(1,4,5)P3, Ins(1,3,4,5)P4, or Ins(1,3,4)P3 at comparable concentrations are tested. Evidence suggests that this differential recognition bears functional significance concerning the intricate roles of profilin and inositol lipids in modulating actin polymerization and PtdIns(4,5)P2 turnover. The relative potency of individual phosphoinositides in offsetting the inhibitory effect of profilin on actin assembly is PtdIns(3,4)P2 > PtdIns(3,4,5)P3 > PtdIns(4,5)P2, consistent with their relative binding affinity with profilin. Moreover, the inhibitory effect of profilin on PLC-γ1-mediated PtdIns(4,5)P2 hydrolysis is overcome by PtdIns(3,4)P2 and PtdIns(3,4,5)P3 through a combined effect of PLC-γI activation and preferential profilin binding. This D-3 phosphoinositide-mediated regulation may represent a new mechanism for controlling PtdIns(4,5)P2 turnover by PLC-γI.

UR - http://www.scopus.com/inward/record.url?scp=0029946425&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029946425&partnerID=8YFLogxK

U2 - 10.1021/bi961878z

DO - 10.1021/bi961878z

M3 - Article

C2 - 8909300

AN - SCOPUS:0029946425

VL - 35

SP - 14027

EP - 14034

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 44

ER -