Dataset Information

Molecular characterization of the eukaryotic Uba4/Urm1 system

ABSTRACT: Ubiquitin-like protein activator 4 (Uba4) is required for the thiolation of uridine bases in eukaryotic transfer RNA. Uba4 catalyzes the sequential adenylation and thiocarboxylation of the C-terminus of Ubiquitin related modifier 1 (Urm1), acting as a hybrid between an E1-like activating enzyme and a sulfur-transferase. Structural and mechanistic details of the eukaryotic Uba4 protein and its respective reaction intermediates remained elusive. Here, we report the high-resolution crystal structures of full length Uba4 from Chaetomium thermophilum and its heterodimeric complex with Urm1. The structures show, how the aligned adenylation and rhodanese-like domains of Uba4 orchestrate substrate binding and specifically recognize and activate Urm1 at its C-terminus. We use complementary assays in vitro and in vivo to functionally validate all our structural findings. Furthermore, we uncover that under oxidative stress the specific relay of catalytic cysteines, similar to E1-E2 cascades, protects Uba4 from covalent conjugation by its own product, namely thiocarboxylated Urm1.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Chaetomium Thermophilum

SUBMITTER: Urszula Jankowska

LAB HEAD: Urszula Jankowska

PROVIDER: PXD015802 | Pride | 2020-07-14

REPOSITORIES: Pride

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Publications

Molecular basis for the bifunctional Uba4-Urm1 sulfur-relay system in tRNA thiolation and ubiquitin-like conjugation.

Pabis Marta M Termathe Martin M Ravichandran Keerthiraju E KE Kienast Sandra D SD Krutyhołowa Rościsław R Sokołowski Mikołaj M Jankowska Urszula U Grudnik Przemysław P Leidel Sebastian A SA Glatt Sebastian S

The EMBO journal 20200909 19

The chemical modification of tRNA bases by sulfur is crucial to tune translation and to optimize protein synthesis. In eukaryotes, the ubiquitin-related modifier 1 (Urm1) pathway is responsible for the synthesis of 2-thiolated wobble uridine (U<sub>34</sub> ). During the key step of the modification cascade, the E1-like activating enzyme ubiquitin-like protein activator 4 (Uba4) first adenylates and thiocarboxylates the C-terminus of its substrate Urm1. Subsequently, activated thiocarboxylated U ...[more]

PMID: 32901956

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Project description:Background:; Osteoblast differentiation requires the coordinated stepwise expression of multiple genes. Histone deacetylase inhibitors (HDIs) accelerate the osteoblast differentiation process by blocking the activity of histone deacetylases (HDACs), which alter gene expression by modifying chromatin structure. We previously demonstrated that HDIs and HDAC3 shRNAs accelerate matrix mineralization and the expression of osteoblast maturation genes (e.g. alkaline phosphatase, osteocalcin). Identifying other genes that are differentially regulated by HDIs might identify new pathways that contribute to osteoblast differentiation. Results:; To identify other osteoblast genes that are altered early by HDIs, we incubated MC3T3-E1 preosteoblasts with HDIs (trichostatin A, MS-275, or valproic acid) for 18 hours in osteogenic conditions. The promotion of osteoblast differentiation by HDIs in this experiment was confirmed by osteogenic assays. Gene expression profiles relative to vehicle-treated cells were assessed by microarray analysis with Affymetrix GeneChip 430 2.0 arrays. The regulation of several genes by HDIs in MC3T3-E1 cells and primary osteoblasts was verified by quantitative real-time PCR. Nine genes were differentially regulated by at least two-fold after exposure to each of the three HDIs and six were verified by PCR in osteoblasts. Four of the verified genes (solute carrier family 9 isoform 3 regulator 1 (Slc9a3r1), sorbitol dehydrogenase 1, a kinase anchor protein, and glutathione S-transferase alpha 4) were induced. Two genes (proteasome subunit, beta type 10 and adaptor-related protein complex AP-4 sigma 1) were suppressed. We also identified eight growth factors and growth factor receptor genes that are significantly altered by each of the HDIs, including Frizzled related proteins 1 and 4, which modulate the Wnt signaling pathway. Conclusions: This study identifies osteoblast genes that are regulated early by HDIs and indicates pathways that might promote osteoblast maturation following HDI exposure. One gene whose upregulation following HDI treatment is consistent with this notion is Slc9a3r1. Also known as NHERF1, Slc9a3r1 is required for optimal bone density. Similarly, the regulation of Wnt receptor genes indicates that this crucial pathway in osteoblast development is also affected by HDIs. These data support the hypothesis that HDIs regulate the expression of genes that promote osteoblast differentiation and maturation. Experiment Overall Design: To identify other osteoblast genes that are altered early by HDIs, we incubated MC3T3-E1 preosteoblasts with HDIs (trichostatin A, MS-275, or valproic acid) or the vehicle control (DMSO) for 18 hours in osteogenic conditions. Gene expression profiles relative to vehicle-treated cells were assessed in triplicate (in some cases quadruplicate) samples by microarray analysis with Affymetrix GeneChip 430 2.0 arrays.

Dataset Information

Molecular characterization of the eukaryotic Uba4/Urm1 system

Publications

Molecular basis for the bifunctional Uba4-Urm1 sulfur-relay system in tRNA thiolation and ubiquitin-like conjugation.

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