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Sorkina T, Cheng MH, Bagalkot TR, Wallace C, Watkins SC, Bahar I, Sorkin A. Direct coupling of oligomerization and oligomerization-driven endocytosis of the dopamine transporter to its conformational mechanics and activity. J Biol Chem 2021; 296:100430. [PMID: 33610553 PMCID: PMC8010718 DOI: 10.1016/j.jbc.2021.100430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/08/2021] [Accepted: 02/16/2021] [Indexed: 12/15/2022] Open
Abstract
Dopamine transporter (DAT) mediates the reuptake of synaptically released dopamine, and thus controls the duration and intensity of dopamine neurotransmission. Mammalian DAT has been observed to form oligomers, although the mechanisms of oligomerization and its role in DAT activity and trafficking remain largely unknown. We discovered a series of small molecule compounds that stabilize trimers and induce high-order oligomers of DAT and concomitantly promote its clathrin-independent endocytosis. Using a combination of chemical cross-linking, fluorescence resonance energy transfer microscopy, antibody-uptake endocytosis assay, live-cell lattice light sheet microscopy, ligand binding and substrate transport kinetics analyses, and molecular modeling and simulations, we investigated molecular basis of DAT oligomerization and endocytosis induced by these compounds. Our study showed that small molecule–induced DAT oligomerization and endocytosis are favored by the inward-facing DAT conformation and involve interactions of four hydrophobic residues at the interface between transmembrane (TM) helices TM4 and TM9. Surprisingly, a corresponding quadruple DAT mutant displays altered dopamine transport kinetics and increased cocaine-analog binding. The latter is shown to originate from an increased preference for outward-facing conformation and inward-to-outward transition. Taken together, our results demonstrate a direct coupling between conformational dynamics of DAT, functional activity of the transporter, and its oligomerization leading to endocytosis. The high specificity of such coupling for DAT makes the TM4-9 hub a new target for pharmacological modulation of DAT activity and subcellular localization.
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Affiliation(s)
- Tatiana Sorkina
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mary Hongying Cheng
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Tarique R Bagalkot
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Callen Wallace
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Simon C Watkins
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Alexander Sorkin
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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Bellam R, Anipindi NR, Jaganyi D. Effect of CTAB and SDS on base hydrolysis of iron(II)-sulphonated and unsulphonated phenyl-1,2,4-triazine complexes - A kinetic and mechanistic study. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Base hydrolysis of tris(3-(2-pyridyl)-5,6-bis(4-phenyl sulphonic acid)-1,2,4-triazine)iron(II) in aqueous, SDS and CTAB media: kinetic and mechanistic study. TRANSIT METAL CHEM 2017. [DOI: 10.1007/s11243-017-0179-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bellam R, Sivamadhavi S, Ramakrishna S, Mambanda A, Jaganyi D, Anipindi N. Octahedral iron(II) complexes with pyridyl triazine and bipyridine ligands – synthesis, computational studies, mechanisms and kinetics with 1,10-phenanthroline and 2,2′,6,2″-terpyridine. J COORD CHEM 2017. [DOI: 10.1080/00958972.2017.1324954] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Rajesh Bellam
- School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg, South Africa
- Department of Physical and Nuclear Chemistry and Chemical Oceanography, Andhra University, Visakhapatnam, India
| | - Surapureddy Sivamadhavi
- Department of Physical and Nuclear Chemistry and Chemical Oceanography, Andhra University, Visakhapatnam, India
| | - Saladi Ramakrishna
- Department of Physical and Nuclear Chemistry and Chemical Oceanography, Andhra University, Visakhapatnam, India
- Department of Chemistry, Adikavi Nannaya University, Rajamahendravaram, India
| | - Allen Mambanda
- School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - Deogratius Jaganyi
- School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - Nageswararao Anipindi
- Department of Physical and Nuclear Chemistry and Chemical Oceanography, Andhra University, Visakhapatnam, India
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Bellam R, Jaganyi D. Substitution Kinetics of [Fe(PDT/PPDT)n(phen)m]2+(n≠m;n,m= 1,2) with 2,2′-Bipyridine, 1,10-Phenanthroline, and 2,2′,6,2″-Terpyridine. INT J CHEM KINET 2017. [DOI: 10.1002/kin.21066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Rajesh Bellam
- School of Chemistry and Physics; University of KwaZulu-Natal; Private Bag X01 Scottsville Pietermaritzburg 3209 South Africa
| | - Deogratius Jaganyi
- School of Chemistry and Physics; University of KwaZulu-Natal; Private Bag X01 Scottsville Pietermaritzburg 3209 South Africa
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