The SUMO conjugation complex self-assembles into nuclear bodies independent of SIZ1 and COP1

Abstract

21 22 One sentence Summary (max 200 characters): 23 SUMO conjugation activity causes formation of SUMO nuclear bodies, which 24 strongly overlap with COP1 bodies thanks to a substrate-binding (VP) motif in the 25 E3 ligase SIZ1 that acts as bridge protein. 26 27 Footnotes: 28 Author contributions: 29 HB conceptualized the project. MM, MK, FM and HB designed experiments. MM, 30 MK, MAM, FM and RK performed experiments. MM, MK, MA, FM and HB 31 analysed the data. MM, MK and HB wrote the MS. MM, MK, FM, MAM, MP and 32 HB reviewed and edited the MS. HB and MP acquired funding and supervised the 33 project. MM and MK contributed equally to this work. 34 35 Abstract 50 Attachment of the small ubiquitin-like modifier SUMO to substrate proteins 51modulates their turnover, activity or interaction partners. An unresolved question is 52 how this SUMO conjugation activity concentrates the enzymes involved and the 53 substrates into uncharacterized nuclear bodies (NBs). We here define the 54 requirements for the formation of SUMO NBs and for their subsequent co-55 localisation with the master regulator of growth, the E3 ubiquitin ligase COP1. COP1 56 activity results in degradation of transcription factors, which primes the 57 transcriptional response that underlies elongation growth induced by night-time and 58 high ambient temperatures (skoto-and thermomorphogenesis, respectively). 59 SUMO conjugation activity itself is sufficient to target the SUMO machinery into NBs. 60Co-localization of these bodies with COP1 requires besides SUMO conjugation 61 activity, a SUMO acceptor site in COP1 and the SUMO E3 ligase SIZ1. We find that 62 SIZ1 docks in the substrate-binding pocket of COP1 via two VP motifs -a known 63 peptide motif of COP1 substrates. The data reveal that SIZ1 physically connects 64 COP1 and SUMO conjugation activity in the same NBs that can also contain the 65 blue-light receptors CRY1 and CRY2. Our findings thus suggest that sumoylation 66 apparently coordinates COP1 activity inside these NBs; a mechanism that 67 potentially explains how SIZ1 and SUMO both control the timing and amplitude of 68 the high-temperature growth response. The strong co-localization of COP1 and 69 SUMO in these NBs might also explain why many COP1 substrates are sumoylated. 70 71 Word count Abstract: 229 72 73 Word count body text: 7174 74 75 two SP-RING domain-containing proteins, PROTEIN INHIBITOR OF ACTIVATED 108 STAT LIKE1 (PIAL1) and PIAL2, were shown to promote SUMO chain formation 109 (Tomanov et al., 2014). There is also a role for the SUMO E2 enzyme in SUMO 110 chain formation (Tomanov et al., 2018). The SUMO E2 interacts via two sites with 111 SUMO: (i) a thioester bond (~) between the catalytic cysteine in the E2 and the C-112 terminal glycine of SUMO (covalent SUMO loading in the catalytic pocket, 113 E2~SUMO) and (ii) a strong nearly constitutive, non-covalent 'SIM-like' interaction 114 (non-covalent SUMO binding, SUMO•E2) (Bencsath et al., 2002; Knipscheer et al., 115 2007; Streich and Lima, 2016). This second non-covalent ...

Developmental Plasticity at High Temperature

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SIZ1-mediated SUMOylation of ROS1 Enhances Its Stability and Positively Regulates Active DNA Demethylation inArabidopsis

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