Distinct regions of Praja-1 E3 ubiquitin-protein ligase selectively bind to docosahexaenoic acid-containing phosphatidic acid and diacylglycerol kinase δ

Yuki Numagami; Fumi Hoshino; Chiaki Murakami; Masayuki Ebina; Fumio Sakane

doi:10.1016/j.bbalip.2022.159265

Distinct regions of Praja-1 E3 ubiquitin-protein ligase selectively bind to docosahexaenoic acid-containing phosphatidic acid and diacylglycerol kinase δ

Biochim Biophys Acta Mol Cell Biol Lipids. 2023 Mar;1868(3):159265. doi: 10.1016/j.bbalip.2022.159265. Epub 2022 Dec 15.

Authors

Yuki Numagami¹, Fumi Hoshino¹, Chiaki Murakami², Masayuki Ebina¹, Fumio Sakane³

Affiliations

¹ Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
² Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; Institute for Advanced Academic Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
³ Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. Electronic address: sakane@faculty.chiba-u.jp.

PMID: 36528254
DOI: 10.1016/j.bbalip.2022.159265

Abstract

1-Stearoyl-2-docosahexaenoyl (18:0/22:6)-phosphatidic acid (PA) interacts with and activates Praja-1 E3 ubiquitin-protein ligase (full length: 615 aa) to ubiquitinate and degrade the serotonin transporter (SERT). SERT modulates serotonergic system activity and is a therapeutic target for depression, autism, obsessive-compulsive disorder, schizophrenia and Alzheimer's disease. Moreover, diacylglycerol kinase (DGK) δ2 (full length: 1214 aa) interacts with Praja-1 in addition to SERT and generates 18:0/22:6-PA, which binds and activates Praja-1. In the present study, we investigated the interaction of Praja-1 with 18:0/22:6-PA and DGKδ2 in more detail. We first found that the N-terminal one-third region (aa 1-224) of Praja-1 bound to 18:0/22:6-PA and that Lys141 in the region was critical for binding to 18:0/22:6-PA. In contrast, the C-terminal catalytic domain of Praja-1 (aa 446-615) interacted with DGKδ2. Additionally, the N-terminal half of the catalytic domain (aa 309-466) of DGKδ2 intensely bound to Praja-1. Moreover, the N-terminal region containing the pleckstrin homology and C1 domains (aa 1-308) and the C-terminal half of the catalytic domain (aa 762-939) of DGKδ2 weakly associated with Praja-1. Taken together, these results reveal new functions of the N-terminal (aa 1-224) and C-terminal (aa 446-615) regions of Praja-1 and the N-terminal half of the catalytic region (aa 309-466) of DGKδ2 as regulatory domains. Moreover, it is likely that the DGKδ2-Praja-1-SERT heterotrimer proximally arranges the 18:0/22:6-PA-producing catalytic domain of DGKδ2, the 18:0/22:6-PA-binding regulatory domain of Praja-1, the ubiquitin-protein ligase catalytic domain of Praja-1 and the ubiquitination acceptor site-containing SERT C-terminal region.

Keywords: Diacylglycerol kinase; Docosahexaenoic acid; E3 ubiquitin-protein ligase; Obsessive-compulsive disorder; Praja-1; Serotonin transporter.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Diacylglycerol Kinase* / metabolism
Docosahexaenoic Acids*
Phosphatidic Acids
Ubiquitin-Protein Ligases / metabolism
Ubiquitination

Substances

Diacylglycerol Kinase
Docosahexaenoic Acids
Phosphatidic Acids
Ubiquitin-Protein Ligases