Transcriptional Gene Silencing Maintained by OTS1 SUMO Protease Requires a DNA-Dependent Polymerase V-Dependent Pathway

Abstract

The expression of genes with aberrant structure is prevented at both the transcriptional and posttranscriptional regulation levels. Aberrant gene silencing at the posttranscriptional level is well studied; however, it is not well understood how aberrant genes are silenced at the transcriptional level. In this study, through genetic screening a transgenic report line that harbors an aberrant gene (35S-LUC, lacking 39-untranslated region [39-UTR]) and lacks luciferase (LUC) activity, we identify that the small ubiquitinlike modifier (SUMO) protease OTS1 gene is required for maintaining the silence of the reporter 35S-LUC and an endogenous mutator-like element MULE-F19G14 at the transcriptional level, which requires DNA-dependent RNA polymerase (Pol) V and DDR complex, but not Pol IV. The increased transcripts in ots1 mutants are terminated by the 39-UTRs of downstream genes. In addition to ots1 mutations, mutations in several known or putative SUMO proteases and two SUMO E3 ligases, SIZ1 and MMS21, have similar effects on this silencing regulation. Taken together, our results reveal that the enzymes involved in the SUMOylation process restrain aberrant gene transcription by using a downstream gene 39-UTR, and this regulation requires a functional Pol V-dependent pathway in Arabidopsis (Arabidopsis thaliana).

Arabidopsis small ubiquitin‐related modifier protease ASP1 positively regulates abscisic acid signaling during early seedling development

“…SUMOylation is implicated in the regulation of abiotic/biotic stress and hormone responses, various developmental processes, metabolism, chromatin remodeling, and transcriptional gene silencing in plants (Park et al ; Park and Yun ; Han et al ; Liu et al ; Zhang et al ). Various components of the SUMO system have been shown to regulate ABA signaling, indicating the importance of SUMOylation in the regulation of ABA signaling.…”

Defining the function of SUMO system in pod development and abiotic stresses in Peanut

“…The spf1 spf2 ULP double mutants exhibit reduced seed set and self-fertilization [10,11]. A similar phenomenon is observed in ots1 ots2 ULP mutants [12,13]. Studies using loss-of-function mutants of E3 ligase have identified many SUMO substrates involved in nutrient homeostasis, signaling by hormones (gibberellins (GA), SA, abscisic acid (ABA)), light-sensing, stem cell maintenance, and the photoperiodic control of flowering [14][15][16][17][18][19].…”

“…For example, ESD4 was found to participate in the regulation of flowering of Arabidopsis [57]. AtSPF1/2 regulate female/male gamete and embryonic development [10,11], and OTS1/2 regulate the growth and salt stress responses in rice [12,24]. The SUMO protease family genes had low levels of expression during in almost all developmental stages, except Ad/ AiFUG1 and Ad/AiSPF1 were relatively higher expressed in shoot tip, suggesting their potential roles in shoot tip development.…”

OTS1‐dependent deSUMOylation increases tolerance to high copper levels in Arabidopsis

“…Arabidopsis thaliana ecotype Columbia‐0 (Col‐0) was used as the WT in all experiments. The mutants ots1‐2 (GK‐207D11, with a T‐DNA insertion in the sixth exon of At1g60220), abi5‐8 (SALK_013163, with a T‐DNA insertion in the 5’‐UTR of At2g36270), and myb30‐2 (with a T‐DNA insertion in the first exon of At3g28910) were obtained from ABRC; ots1‐3 (containing a G‐to‐A mutation at the last nucleotide in the eighth intron of At1g60220) (Liu et al ) was kindly provided by Dr. Yan Guo from China Agricultural University.…”

“…Statistical significance was determined by Student's t-test; significant differences are indicated by an asterisk ( Ã , P 0.05). At1g60220) (Liu et al 2016) was kindly provided by Dr. Yan Guo from China Agricultural University.…”