Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors
BACKGROUND AND PURPOSE: Adenophostin A (AdA) is a potent agonist of inositol 1,4,5-trisphosphate receptors (IP 3R). AdA shares with IP 3 the essential features of all IP 3R agonists, namely structures equivalent to the 4,5-bisphosphate and 6-hydroxyl of IP 3, but the basis of its increased affinity...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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Wiley
2010
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| _version_ | 1797089384208531456 |
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| author | Rossi, A Sureshan, K Riley, A Potter, B Taylor, C |
| author_facet | Rossi, A Sureshan, K Riley, A Potter, B Taylor, C |
| author_sort | Rossi, A |
| collection | OXFORD |
| description | BACKGROUND AND PURPOSE: Adenophostin A (AdA) is a potent agonist of inositol 1,4,5-trisphosphate receptors (IP 3R). AdA shares with IP 3 the essential features of all IP 3R agonists, namely structures equivalent to the 4,5-bisphosphate and 6-hydroxyl of IP 3, but the basis of its increased affinity is unclear. Hitherto, the 2'-phosphate of AdA has been thought to provide a supra-optimal mimic of the 1-phosphate of IP 3. EXPERIMENTAL APPROACH: We examined the structural determinants of AdA binding to type 1 IP 3R (IP 3R1). Chemical synthesis and mutational analysis of IP 3R1 were combined with 3H-IP 3 binding to full-length IP 3R1 and its N-terminal fragments, and Ca 2+ release assays from recombinant IP 3R1 expressed in DT40 cells. KEY RESULTS: Adenophostin A is at least 12-fold more potent than IP 3 in functional assays, and the IP 3-binding core (IBC, residues 224-604 of IP 3R1) is sufficient for this high-affinity binding of AdA. Removal of the 2'-phosphate from AdA (to give 2'-dephospho-AdA) had significantly lesser effects on its affinity for the IBC than did removal of the 1-phosphate from IP 3 (to give inositol 4,5-bisphosphate). Mutation of the only residue (R568) that interacts directly with the 1-phosphate of IP 3 decreased similarly (by -30-fold) the affinity for IP 3 and AdA, but mutating R504, which has been proposed to form a cation-Π interaction with the adenine of AdA, more profoundly reduced the affinity of IP 3R for AdA (353-fold) than for IP 3 (13-fold). CONCLUSIONS AND IMPLICATIONS: The 2'-phosphate of AdA is not a major determinant of its high affinity. R504 in the receptor, most likely via a cation-Π interaction, contributes specifically to AdA binding. |
| first_indexed | 2024-03-07T03:03:22Z |
| format | Journal article |
| id | oxford-uuid:b1b4edeb-5b5e-4ffe-ac4a-1a4f5fb9aad4 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:03:22Z |
| publishDate | 2010 |
| publisher | Wiley |
| record_format | dspace |
| spelling | oxford-uuid:b1b4edeb-5b5e-4ffe-ac4a-1a4f5fb9aad42022-03-27T04:06:02ZSelective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptorsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b1b4edeb-5b5e-4ffe-ac4a-1a4f5fb9aad4EnglishSymplectic Elements at OxfordWiley2010Rossi, ASureshan, KRiley, APotter, BTaylor, CBACKGROUND AND PURPOSE: Adenophostin A (AdA) is a potent agonist of inositol 1,4,5-trisphosphate receptors (IP 3R). AdA shares with IP 3 the essential features of all IP 3R agonists, namely structures equivalent to the 4,5-bisphosphate and 6-hydroxyl of IP 3, but the basis of its increased affinity is unclear. Hitherto, the 2'-phosphate of AdA has been thought to provide a supra-optimal mimic of the 1-phosphate of IP 3. EXPERIMENTAL APPROACH: We examined the structural determinants of AdA binding to type 1 IP 3R (IP 3R1). Chemical synthesis and mutational analysis of IP 3R1 were combined with 3H-IP 3 binding to full-length IP 3R1 and its N-terminal fragments, and Ca 2+ release assays from recombinant IP 3R1 expressed in DT40 cells. KEY RESULTS: Adenophostin A is at least 12-fold more potent than IP 3 in functional assays, and the IP 3-binding core (IBC, residues 224-604 of IP 3R1) is sufficient for this high-affinity binding of AdA. Removal of the 2'-phosphate from AdA (to give 2'-dephospho-AdA) had significantly lesser effects on its affinity for the IBC than did removal of the 1-phosphate from IP 3 (to give inositol 4,5-bisphosphate). Mutation of the only residue (R568) that interacts directly with the 1-phosphate of IP 3 decreased similarly (by -30-fold) the affinity for IP 3 and AdA, but mutating R504, which has been proposed to form a cation-Π interaction with the adenine of AdA, more profoundly reduced the affinity of IP 3R for AdA (353-fold) than for IP 3 (13-fold). CONCLUSIONS AND IMPLICATIONS: The 2'-phosphate of AdA is not a major determinant of its high affinity. R504 in the receptor, most likely via a cation-Π interaction, contributes specifically to AdA binding. |
| spellingShingle | Rossi, A Sureshan, K Riley, A Potter, B Taylor, C Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title | Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title_full | Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title_fullStr | Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title_full_unstemmed | Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title_short | Selective determinants of inositol 1,4,5-trisphosphate and adenophostin A interactions with type 1 inositol 1,4,5-trisphosphate receptors |
| title_sort | selective determinants of inositol 1 4 5 trisphosphate and adenophostin a interactions with type 1 inositol 1 4 5 trisphosphate receptors |
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