SUMOylation of the mitochondrial fission protein Drpl occurs at multiple nonconsensus sites within the B domain and is linked to its activity cycle

Abstract

Dynamin-related protein (Drp) 1 is a key regulator of mitochondrial fission and is composed of GTP-binding, Middle, insert B, and C-terminal GTPase effector (GED) domains. Drp1 associates with mitochondrial fission sites and promotes membrane constriction through its intrinsic GTPase activity. The mechanisms that regulate Drp1 activity remain poorly understood but are likely to involve reversible post-translational modifications, such as conjugation of small ubiquitin-like modifier (SUMO) proteins. Through a detailed analysis, we find that Drp1 interacts with the SUMO-conjugating enzyme Ubc9 via multiple regions and demonstrate that Drp1 is a direct target of SUMO modification by all three SUMO isoforms. While Drp1 does not harbor consensus SUMOylation sequences, our analysis identified2 clusters of lysine residues within the B domain that serve as noncanonical conjugation sites. Although initial analysis indicates that mitochondrial recruitment of ectopically expressed Drp1 in response to staurosporine is unaffected by loss of SUMOylation, we find that Drp1 SUMOylation is enhanced in the context of the K38A mutation. This dominant-negative mutant, which is deficient in GTP binding and hydrolysis, does not associate with mitochondria and prevents normal mitochondrial fission. This finding suggests that SUMOylation of Drp1 is linked to its activity cycle and is influenced by Drp1 localization.

Interchangeable adaptors regulate mitochondrial dynamin assembly for membrane scission

“…In addition, the physiological circumstances (i.e., apoptosis, mitophagy) in which each adaptor is activated might differ. Documented posttranslational modifications of Drp1 including phosphorylation (3,(38)(39)(40)(41)(42), sumoylation (43)(44)(45)(46), nitrosylation (47), and ubiquitination (48-52) also could influence the identity of the adaptor used for fission, as could posttranslational modifications of the adaptors themselves. Finally, it is possible that multiple adaptors work together with Drp1 at a single division site.…”

Mitochondrial dynamics in neuronal injury, development and plasticity

“…However, other groups did not observe increased Drp1 S-nitrosylation but, instead, proposed increased phosphorylation of S616 and the subsequent recruitment of Drp1 to mitochondria as a mechanism to trigger the mitochondrial fragmentation found in neurodegenerative diseases (Bossy et al, 2010;Zhang et al, 2016). In addition, Drp1 is SUMOylated at multiple lysine residues, which has been suggested to stabilize Drp1 oligomers at the OMM in order to promote mitochondrial fission and initiate apoptosis (Wasiak et al, 2007;Harder et al, 2004;Guo et al, 2013a;Figueroa-Romero et al, 2009). Drp1 is also subject to alternative splicing and can include up to three alternative exons that give rise to eight different protein isoforms in mammals (Fig.…”

Modulation of Dynamin-related Protein 1 (DRP1) Function by Increased O-linked-β-N-acetylglucosamine Modification (O-GlcNAc) in Cardiac Myocytes

“…Although involved in mitochondrial function, DRP1 is mostly localized in cytoplasm with ϳ3% associated with the mitochondrial membrane at rest under physiological conditions (4). The functional properties of DRP1 are modulated by a number of posttranslational modifications, including phosphorylation (5-7), SUMOylation (8), ubiquitination (9), and S-nitrosylation (10). DRP1 is phosphorylated at two sites, serine 616 (Ser-616 and 637 Ser-637, referring to the sequence of the human DRP1), which are well conserved (5,11,12).…”