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Structure of the Siz/PIAS SUMO E3 ligase Siz1 and determinants required for SUMO modification of PCNA.

ABSTRACT: Siz1 is a founding member of the Siz/PIAS RING family of SUMO E3 ligases. The X-ray structure of an active Siz1 ligase revealed an elongated tripartite architecture comprised of an N-terminal PINIT domain, a central zinc-containing RING-like SP-RING domain, and a C-terminal domain we term the SP-CTD. Structure-based mutational analysis and biochemical studies show that the SP-RING and SP-CTD are required for activation of the E2 approximately SUMO thioester, while the PINIT domain is essential for redirecting SUMO conjugation to the proliferating cell nuclear antigen (PCNA) at lysine 164, a nonconsensus lysine residue that is not modified by the SUMO E2 in the absence of Siz1. Mutational analysis of Siz1 and PCNA revealed surfaces on both proteins that are required for efficient SUMO modification of PCNA in vitro and in vivo.

SUBMITTER: Yunus AA

PROVIDER: S-EPMC2771690 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Structure of the Siz/PIAS SUMO E3 ligase Siz1 and determinants required for SUMO modification of PCNA.

Yunus Ali A AA Lima Christopher D CD

Molecular cell 20090901 5

Siz1 is a founding member of the Siz/PIAS RING family of SUMO E3 ligases. The X-ray structure of an active Siz1 ligase revealed an elongated tripartite architecture comprised of an N-terminal PINIT domain, a central zinc-containing RING-like SP-RING domain, and a C-terminal domain we term the SP-CTD. Structure-based mutational analysis and biochemical studies show that the SP-RING and SP-CTD are required for activation of the E2 approximately SUMO thioester, while the PINIT domain is essential f ...[more]

PMID: 19748360

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The Arabidopsis SUMO E3 ligase SIZ1 mediates the temperature dependent trade-off between plant immunity and growth

Project description:Increased ambient temperature is widely considered to be inhibitory to basal and effector-triggered plant immunity. For example, SNC1-dependent auto-immunity in Arabidopsis results in enhanced basal resistance at 22ºC, which is fully suppressed at 28ºC. The sumoylation mutant siz1 also displays auto-immunity at 22ºC. We find that its auto-immunity is sustained at 28ºC while still requiring PAD4/EDS1 and SNC1 function. Moreover, its rosette size does not fully recover at 28ºC, which is normally seen for SNC1 gain-of-function mutants. Related, thermomorphogenesis is also compromised in the SUMO mutants. This role of SIZ1 in growth regulation does not depend on PAD4 or SNC1. In corroboration, SUMO mutants show a global delay in their transcriptional profile for thermosensitive growth regulators and these differentially expressed genes show an overrepresentation for PIF4 genomic targets. This transcription factor (TF) PIF4 is the central regulator of thermomorphogenesis, while also inhibiting plant immunity at 28ºC. Our findings thus reveal that SUMO conjugation has a central role in PIF4 regulation prioritizing growth over immunity at elevated temperatures. Such molecular understanding of how temperature affects growth over immunity is important to mitigate the effects of climate change on agriculture This experiment we have examined how gene expression is affected in two SUMO mutants (siz1-2; sumo1 amiR-SUMO1 [aka. sumo1/2KD] ) when the plants are placed at 28C constant ambient temperature, which is a condition normally used to induce thermomorphogenesis. We used as control the pad1-4 background, as the siz1-2 and sumo1/2KD mutants normailly suffer from constitutive defence signalling due hyperaccumulation of SA, which is suppressed by introgression of pad4 in these backgrounds.

2018-01-02 | GSE97641 | GEO

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