Structure and activation of the RING E3 ubiquitin ligase TRIM72 on the membrane.

Defects in plasma membrane repair can lead to muscle and heart diseases in humans. Tripartite motif-containing protein (TRIM)72 (mitsugumin 53; MG53) has been determined to rapidly nucleate vesicles at the site of membrane damage, but the underlying molecular mechanisms remain poorly understood. Here we present the structure of Mus musculus TRIM72, a complete model of a TRIM E3 ubiquitin ligase.

Cryo-EM structure of the Hippo signaling integrator human STRIPAK.

The striatin-interacting phosphatase and kinase (STRIPAK) complex is a large, multisubunit protein phosphatase 2A (PP2A) assembly that integrates diverse cellular signals in the Hippo pathway to regulate cell proliferation and survival. The architecture and assembly mechanism of this critical complex are poorly understood. Using cryo-EM, we determine the structure of the human STRIPAK core comprising PP2AA, PP2AC, STRN3, STRIP1, and MOB4 at 3.

Cryo-EM Structures of Human Drosha and DGCR8 in Complex with Primary MicroRNA.

Metazoan microRNAs require specific maturation steps initiated by Microprocessor, comprising Drosha and DGCR8. Lack of structural information for the assembled complex has hindered an understanding of how Microprocessor recognizes primary microRNA transcripts (pri-miRNAs). Here we present a cryoelectron microscopy structure of human Microprocessor with a pri-miRNA docked in the active site, poised for cleavage.

Publisher Correction: Heme enables proper positioning of Drosha and DGCR8 on primary microRNAs.

The original version of this Article contained an error in Fig. 1. In panel d, the model on the right of the panel was incorrectly labeled '+Heme', and should have read '- Heme'.

Mechanistic insight into TRIP13-catalyzed Mad2 structural transition and spindle checkpoint silencing.

The spindle checkpoint maintains genomic stability and prevents aneuploidy. Unattached kinetochores convert the latent open conformer of the checkpoint protein Mad2 (O-Mad2) to the active closed conformer (C-Mad2), bound to Cdc20. C-Mad2-Cdc20 is incorporated into the mitotic checkpoint complex (MCC), which inhibits the anaphase-promoting complex/cyclosome (APC/C).

Heme enables proper positioning of Drosha and DGCR8 on primary microRNAs.

MicroRNAs regulate the expression of many proteins and require specific maturation steps. Primary microRNA transcripts (pri-miRs) are cleaved by Microprocessor, a complex containing the RNase Drosha and its partner protein, DGCR8. Although DGCR8 is known to bind heme, the molecular role of heme in pri-miR processing is unknown.

HP1BP3, a Chromatin Retention Factor for Co-transcriptional MicroRNA Processing.

Recent studies suggest that the microprocessor (Drosha-DGCR8) complex can be recruited to chromatin to catalyze co-transcriptional processing of primary microRNAs (pri-miRNAs) in mammalian cells. However, the molecular mechanism of co-transcriptional miRNA processing is poorly understood. Here we find that HP1BP3, a histone H1-like chromatin protein, specifically associates with the microprocessor and promotes global miRNA biogenesis in human cells.

Crystallization and preliminary X-ray analysis of the C-terminal fragment of Ski7 from Saccharomyces cerevisiae.

Ski7 (superkiller protein 7) plays a critical role in the mRNA surveillance pathway. The C-terminal fragment of Ski7 (residues 520-747) from Saccharomyces cerevisiae was heterologously expressed in Escherichia coli and purified to homogeneity. It was successfully crystallized and preliminary X-ray data were collected to 2.

MG53-induced IRS-1 ubiquitination negatively regulates skeletal myogenesis and insulin signalling.

Mitsugumin 53 (MG53) negatively regulates skeletal myogenesis by targeting insulin receptor substrate 1 (IRS-1). Here, we show that MG53 is an ubiquitin E3 ligase that induces IRS-1 ubiquitination with the help of an E2-conjugating enzyme, UBE2H. Molecular manipulations that disrupt the E3-ligase function of MG53 abolish IRS-1 ubiquitination and enhance skeletal myogenesis.

Change in single cystathionine β-synthase domain-containing protein from a bent to flat conformation upon adenosine monophosphate binding.

Cystathionine β-synthase (CBS) domains are small intracellular modules that can act as binding domains for adenosine derivatives, and they may regulate the activity of associated enzymes or other functional domains. Among these, the single CBS domain-containing proteins, CBSXs, from Arabidopsis thaliana, have recently been identified as redox regulators of the thioredoxin system. Here, the crystal structure of CBSX2 in complex with adenosine monophosphate (AMP) is reported at 2.

A cystathionine-β-synthase domain-containing protein, CBSX2, regulates endothecial secondary cell wall thickening in anther development.

Anther formation and dehiscence are complex pivotal processes in reproductive development. The secondary wall thickening in endothecial cells of the anther is a known prerequisite for successful anther dehiscence. However, many gaps remain in our understanding of the regulatory mechanisms underlying anther dehiscence in planta, including a possible role for jasmonic acid (JA) and H(2)O(2) in secondary wall thickening of endothecial cells.

Crystal structure of the single cystathionine β-synthase domain-containing protein CBSX1 from Arabidopsis thaliana.

The single cystathionine β-synthase (CBS) pair proteins from Arabidopsis thaliana have been identified as being a redox regulator of the thioredoxin (Trx) system. CBSX1 and CBSX2, which are two of the six Arabidopsis cystathione β-synthase domain-containing proteins that contain only a single CBS pair, have close sequence similarity. Recently, the crystal structure of CBSX2 was determined and a significant portion of the internal region was disordered.

Crystal structure of Pyrococcus furiosus PF2050, a member of the DUF2666 protein family.

Pyrococcus furiosus PF2050 is an uncharacterized putative protein that contains two DUF2666 domains. Functional and structural studies of PF2050 have not previously been performed. In this study, we determined the crystal structure of PF2050.

Single cystathionine β-synthase domain-containing proteins modulate development by regulating the thioredoxin system in Arabidopsis.

Plant thioredoxins (Trxs) participate in two redox systems found in different cellular compartments: the NADP-Trx system (NTS) in the cytosol and mitochondria and the ferredoxin-Trx system (FTS) in the chloroplast, where they function as redox regulators by regulating the activity of various target enzymes. The identities of the master regulators that maintain cellular homeostasis and modulate timed development through redox regulating systems have remained completely unknown. Here, we show that proteins consisting of a single cystathionine β-synthase (CBS) domain pair stabilize cellular redox homeostasis and modulate plant development via regulation of Trx systems by sensing changes in adenosine-containing ligands.

Crystal structure of ubiquitin-like small archaeal modifier protein 1 (SAMP1) from Haloferax volcanii.

The ubiquitin-like (Ubl) system has been shown to be ubiquitous in all three kingdoms of life following the very recent characterization of ubiquitin-like small archaeal modifier proteins (SAMP1 and 2) from Haloferax volcanii. The ubiquitin (Ub) and Ubl molecules in eukaryotes have been studied extensively and their cellular functions are well established. Biochemical and structural data pertaining to prokaryotic Ubl protein (Pup) continue to be reported.

Structural basis for the recognition of N-end rule substrates by the UBR box of ubiquitin ligases.

The N-end rule pathway is a regulated proteolytic system that targets proteins containing destabilizing N-terminal residues (N-degrons) for ubiquitination and proteasomal degradation in eukaryotes. The N-degrons of type 1 substrates contain an N-terminal basic residue that is recognized by the UBR box domain of the E3 ubiquitin ligase UBR1. We describe structures of the UBR box of Saccharomyces cerevisiae UBR1 alone and in complex with N-degron peptides, including that of the cohesin subunit Scc1, which is cleaved and targeted for degradation at the metaphase-anaphase transition.

Purification, crystallization and preliminary X-ray diffraction analysis of a cystathionine beta-synthase domain-containing protein, CDCP2, from Arabidopsis thaliana.

Cystathione beta-synthase domain-containing protein 2 (CDCP2) from Arabidopsis thaliana has been overexpressed and purified to homogeneity. As an initial step towards three-dimensional structure determination, crystals of recombinant CDCP2 protein have been obtained using polyethylene glycol 8000 as a precipitant. The crystals diffracted to 2.