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O-GlcNAc transferase recognizes protein substrates using an asparagine ladder in the TPR superhelix

ABSTRACT: Abstract: The essential mammalian enzyme O-GlcNAc Transferase (OGT) is uniquely responsible for transferring N-acetylglucosamine to over a thousand nuclear and cytoplasmic proteins, yet there is no known consensus sequence and it remains unclear how OGT recognizes its substrates. To address this question, we have developed a protein microarray assay that chemoenzymatically labels de novo sites of glycosylation with biotin, allowing us to simultaneously as-sess OGT activity across >6000 human proteins. We used this assay to examine the contribution of a conserved asparagine ladder within the lumen of OGT’s superhelical tetratri-copeptide repeat (TPR) domain to substrate selection. When these residues were mutated, OGT retained full activity against short peptides, but showed low to no activity against most of the OGT substrates on the microarray. O-GlcNAcylation of protein substrates in cell extracts was also greatly attenuated. We conclude that OGT recognizes a majority of its substrates by binding them to the asparagine ladder in the TPR lumen proximal to the catalytic domain. This series contains microarray data both comparing the new chemoenzymatic method to antibody-based detection as well as comparing arrays treated with wild-type OGT, 5N5A mutant OGT, or controls not treated with enzyme. Note: all CTD-stained arrays or control array raw files are contained in GSE107911_RAW.tar

ORGANISM(S): Homo sapiens

PROVIDER: GSE107911 | GEO | 2018/02/26

REPOSITORIES: GEO

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O-GlcNAc transferase recognizes protein substrates using an asparagine ladder in the TPR superhelix

Project description:O-GlcNAc transferase recognizes protein substrates using an asparagine ladder in the TPR superhelix

| PRJNA421921 | ENA

Aspartate Residues Far From the Active Site Drive O-GlcNAc Transferase Substrate Selection

Project description:Abstract: O-GlcNAc is an abundant post-translational modification found on nuclear and cytoplasmic proteins in all metazoans. This modification regulates a wide variety of cellular processes, and elevated O-GlcNAc levels have been implicated in cancer progression. A single essential enzyme, O-GlcNAc transferase (OGT), is responsible for all nucleocytoplasmic O-GlcNAcylation. Understanding how this enzyme chooses its substrates is critical for understanding, and potentially manipulating, its functions. Here we use protein microarray technology and proteome-wide glycosylation profiling to show that conserved aspartate residues in the tetratricopeptide repeat (TPR) lumen of OGT drive substrate selection. Changing these residues to alanines alters substrate selectivity and unexpectedly increases rates of protein glycosylation. Our findings support a model where sites of glycosylation for many OGT substrates are determined by TPR domain contacts to substrate side chains five to fifteen residues C-terminal to the glycosite. In addition to guiding design of inhibitors that target OGT's TPR domain, this information will inform efforts to engineer substrates to explore biological functions.

2019-07-24 | GSE132205 | GEO

Aspartate residues far from the active site drive O-GlcNAc transferase substrate selection

Project description:Here we use protein microarray technology and proteome-wide glycosylation profiling to show that conserved aspartate residues in the tetratricopeptide repeat (TPR) lumen of OGT drive substrate selection. Changing these residues to alanines alters substrate selectivity and unexpectedly increases rates of protein glycosylation. Our findings support a model where sites of glycosylation for many OGT substrates are determined by TPR domain contacts to substrate side chains five to fifteen residues Cterminal to the glycosite. In addition to guiding design of inhibitors that target OGT’s TPR domain, this information will inform efforts to engineer substrates to explore biological functions.

2019-07-26 | PXD014731 | Pride

Truncation of the TPR domain of OGT alters substrate and glycosite selection

Project description:Nucleocytoplasmic O-linked N-acetylglucosamine (O-GlcNAc) is an essential post-translational modification that is installed to thousands of protein substrates by O-GlcNAc transferase (OGT). Substrate selection by OGT and its isoforms is primarily mediated by the tetratricopeptide repeat (TPR) domain, yet the impact of truncations to the TPR domain on substrate and glycosite selection remains unresolved. Here, we report the effects of TPR truncations on the substrate and glycosite selection of OGT against the model protein GFP-JunB and the surrounding O-GlcNAc proteome in U2OS cells. Truncation of the TPR domain of OGT maintains glycosyltransferase activity but alters subcellular localization in cells. Examination of the glycoproteome across the TPR truncations revealed the broadest substrate activity from the canonical nucleocytoplasmic OGT, with the greatest changes in O-GlcNAc occurring on proteins associated with mRNA splicing processes. Glycosite analysis revealed alterations to the O-GlcNAc consensus sequence globally and differential glycosite selectivity on GFP-JunB as a function of the OGT TPR isoform. This dataset provides a foundation to analyze how perturbations to the TPR domain and expression of OGT isoforms affects the glycosylation of substrates, which will be critical for future protein engineering of OGT, the biology of OGT isoforms, and diseases associated with the TPR domain of OGT.

2021-11-01 | PXD028141 | Pride

O-GlcNAc pattern of sOGT regulates its substrate selectivity and function

Project description:O-GlcNAcylation occurs on thousands of proteins involved in various cellular events. O-GlcNAc transferase (OGT), one of the enzymes responsible for protein O-GlcNAcylation, is known to be auto-O-GlcNAcylated at multiple sites. However, the role of O-GlcNAcylation on OGT is still unknown. Here, we report the role of O-GlcNAcylation on short form OGT (sOGT). By LC-ETD-MS analysis and western blot, we show that sOGT was mainly O-GlcNAcylated in the tetratricopeptide repeat (TPR) motifs with T12 and S56 being two “key” sites. T12 was a predominant O-GlcNAcylation site and the absence of S56 O-GlcNAcylation enhanced sOGT O-GlcNAcylation level. We found that O-GlcNAcylation of sOGT did not affect the enzyme activity but increased its binding to substrate proteins. S56A bound to and hence glycosylated more proteins, while T12A associated with fewer substrates. Proteomic studies combined with cell proliferation/cell cycle analyses indicated that S56A substantially enhanced cell proliferation, while T12A reduced it, and T12A led to a G2/M cell cycle arrest, due to O-GlcNAcylation of diverse proteins. These findings demonstrate that the O-GlcNAc pattern on sOGT modulates its function in cells by targeting different proteins.

2019-09-16 | PXD010173 | Pride

O-GlcNAc pattern of sOGT regulates its substrate selectivity and function

2019-09-16 | PXD009731 | Pride

Ogt chromatin recruitment is mediated by TET proteins in mouse ES cells [expression array]

Project description:O-linked N-acetylglucosamine (O-GlcNAc ) transferase (OGT) activity is essential for embryonic stem (ES) cell viability and mouse development. OGT is present in both cytoplasm and nucleus of different cell types and mediates serine or threonine glycosylation. The Ogt gene locus resides on the X-chromosome and its activity is required for the viability of male ES cells. Using Ogt conditional knock out (KO) ES cells it was shown the failure of establishing stable KO ES clones further suggesting that Ogt activity is required for ES cell self-renewal and pluripotency. For understanding these changes, we performed global gene expression upon silencing of Ogt mediated by esiRNA in mouse Embryonic Stem Cells. Total RNA was extracted from E14 ES cells (derived from Ola129 mice) transiently transfected with Ogt specific and control esiRNA oligos 48 hrs. post-transfection.

2013-01-06 | E-GEOD-39321 | biostudies-arrayexpress

OGT, H2B S112GlcNAc, TET2 ChIP-seq results

Project description:TET2 directly interacts with OGT, which is important for the chromatin association of OGT in vivo. Although this specific interaction does not regulate the enzymatic activity of TET2, it facilitates OGT-dependent histone O-GlcNAcylation. Moreover, OGT associates with TET2 at transcription starting sites (TSS). Down-regulation of TET2 reduces the amount of H2B S112 GlcNAc marks in vivo, which are associated with gene transcription regulation. We found that OGT interacts with TET2 tightly. Using ChIP-seq with specific antibodies, we tested the co-localization of TET2 and OGT in genome level.

2012-12-11 | E-GEOD-41720 | biostudies-arrayexpress

Dot1L recruits OGT target chromatin to regulate histones O-GlcNAcylation

Project description:OGT (O-GlcNAc transferase) is the distinctive enzyme responsible for catalyzing O-GlcNAc to the serine or threonine residues of thousands of cytoplasm and nuclear proteins that are involved in DNA damage, RNA splicing, and transcription preinitiation and initiation complex assembly. However, the molecular mechanism by OGT regulating gene transcription remains elusive. Using proximity labeling based mass spectrometry, we searched for functional partners of OGT and found that Dot1L, the conserved and unique histone methyltransferase mediated histone H3 lys79 methylation required for gene transcription, DNA damage repair, cell proliferation, and embryo development, interacts with OGT. Although this specific interaction does not regulate the enzymatic activity of Dot1L, it facilitates OGT-dependent histones O-GlcNAcylation. Moreover, OGT associates with Dot1L at transcription start sites, and depleting Dot1L decreased OGT associated with chromatin globally. Notably, downregulation of Dot1L reduces the levels of histone H2B S112 O-GlcNAcylation and histone H2B K120 ubiquitination in vivo, which are associated with gene transcription regulation. Taken together, these results reveal a Dot1L-dependent O-GlcNAcylation of chromatin.

2022-04-06 | GSE200059 | GEO

TET2 and TET3 regulate GlcNAcylation and H3K4 methylation through OGT and SET1/COMPASS

Project description:TET proteins convert 5-methylcytosine to 5-hydroxymethylcytosine, an emerging dynamic epigenetic state of DNA that can influence transcription. Evidence has linked TET1 function to epigenetic repression complexes, yet mechanistic information, especially for the TET2 and TET3 proteins, remains limited. Here, we show a direct interaction of TET2 and TET3 with O-GlcNAc transferase (OGT). OGT does not appear to influence hmC activity, rather TET2 and TET3 promote OGT activity. TET2/3-OGT co-localize on chromatin at active promoters enriched for H3K4me3 and reduction of either TET2/3 or OGT activity results in a direct decrease in H3K4me3 and concomitant decreased transcription. Further, we show that Host Cell Factor 1 (HCF1), a component of the H3K4 methyltransferase SET1/COMPASS complex, is a specific GlcNAcylation target of TET2/3-OGT, and modification of HCF1 is important for the integrity of SET1/COMPASS. Additionally, we find both TET proteins and OGT activity promote binding of the SET1/COMPASS H3K4 methyltransferase, SETD1A, to chromatin. Finally, studies in Tet2 knockout mouse bone marrow tissue extend and support the data as decreases are observed of global GlcNAcylation and also of H3K4me3, notably at several key regulators of haematopoiesis. Together, our results unveil a step-wise model, involving TET-OGT interactions, promotion of GlcNAcylation, and influence on H3K4me3 via SET1/COMPASS, highlighting a novel means by which TETs may induce transcriptional activation. ChIP-Seq experiments were performed on Illumina HiScanSQ sequencer in wild-type HEK293T cells for H3K4me3 histone marks, O-GlcNAc and HCF1, for HT-TET2, HT-TET3 and HT-OGT in HEK293T cells overexpressing those three fusion proteins and in TET2 Kd HEK293T cells for H3K4me3 histone marks. ChIP-Seqs were also performed in mouse bone marrow tissues for H3K4me3 histone marks, O-GlcNAc, endogenous Tet2 and in Tet2 Ko bone marrow tissues for H3K4me3 histone marks.

2013-02-07 | E-GEOD-36620 | biostudies-arrayexpress

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