Julius Rabl

Last Name

Rabl

First Name

Julius

ORCID

0000-0001-6375-852X

Organisational unit

02891 - ScopeM / ScopeM

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Publications 1 - 10 of 11

The human GID complex engages two independent modules for substrate recruitment
Mohamed, Weaam I.; Park, Sophia L.; Rabl, Julius; et al. (2021)
EMBO Reports
The human GID (hGID) complex is a conserved E3 ubiquitin ligase regulating diverse biological processes, including glucose metabolism and cell cycle progression. However, the biochemical function and substrate recognition of the multi-subunit complex remain poorly understood. Using biochemical assays, cross-linking mass spectrometry, and cryo-electron microscopy, we show that hGID engages two distinct modules for substrate recruitment, dependent on either WDR26 or GID4. WDR26 and RanBP9 cooperate to ubiquitinate HBP1 in vitro, while GID4 is dispensable for this reaction. In contrast, GID4 functions as an adaptor for the substrate ZMYND19, which surprisingly lacks a Pro/N-end degron. GID4 substrate binding and ligase activity is regulated by ARMC8α, while the shorter ARMC8β isoform assembles into a stable hGID complex that is unable to recruit GID4. Cryo-EM reconstructions of these hGID complexes reveal the localization of WDR26 within a ring-like, tetrameric architecture and suggest that GID4 and WDR26/Gid7 utilize different, non-overlapping binding sites. Together, these data advance our mechanistic understanding of how the hGID complex recruits cognate substrates and provides insights into the regulation of its E3 ligase activity.
Ribosomal protein RPL39L is an efficiency factor in the cotranslational folding of a subset of proteins with alpha helical domains
Banerjee, Arka; Ataman, Meric; Smialek, Maciej Jerzy; et al. (2024)
Nucleic Acids Research
Increasingly many studies reveal how ribosome composition can be tuned to optimally translate the transcriptome of individual cell types. In this study, we investigated the expression pattern, structure within the ribosome and effect on protein synthesis of the ribosomal protein paralog 39L (RPL39L). With a novel mass spectrometric approach we revealed the expression of RPL39L protein beyond mouse germ cells, in human pluripotent cells, cancer cell lines and tissue samples. We generated RPL39L knock-out mouse embryonic stem cell (mESC) lines and demonstrated that RPL39L impacts the dynamics of translation, to support the pluripotency and differentiation, spontaneous and along the germ cell lineage. Most differences in protein abundance between WT and RPL39L KO lines were explained by widespread autophagy. By CryoEM analysis of purified RPL39 and RPL39L-containing ribosomes we found that, unlike RPL39, RPL39L has two distinct conformations in the exposed segment of the nascent peptide exit tunnel, creating a distinct hydrophobic patch that has been predicted to support the efficient co-translational folding of alpha helices. Our study shows that ribosomal protein paralogs provide switchable modular components that can tune translation to the protein production needs of individual cell types.
The crystal structure of the eukaryotic 40S ribosomal subunit in complex with eIF1 and eIF1A
Weisser, Melanie; Voigts-Hoffmann, Felix; Rabl, Julius; et al. (2013)
Nature Structural & Molecular Biology
Structural conservation of HBV-like capsid proteins over hundreds of millions of years despite the shift from non-enveloped to enveloped life-style
Pfister, Sara; Rabl, Julius; Wiegand, Thomas; et al. (2023)
Nature Communications
The discovery of nackednaviruses provided new insight into the evolutionary history of the hepatitis B virus (HBV): The common ancestor of HBV and nackednaviruses was non-enveloped and while HBV acquired an envelope during evolution, nackednaviruses remained non-enveloped. We report the capsid structure of the African cichlid nackednavirus (ACNDV), determined by cryo-EM at 3.7 Å resolution. This enables direct comparison with the known capsid structures of HBV and duck HBV, prototypic representatives of the mammalian and avian lineages of the enveloped Hepadnaviridae, respectively. The sequence identity with HBV is 24% and both the ACNDV capsid protein fold and the capsid architecture are very similar to those of the Hepadnaviridae and HBV in particular. Acquisition of the hepadnaviral envelope was thus not accompanied by a major change in capsid structure. Dynamic residues at the spike tip are tentatively assigned by solid-state NMR, while the C-terminal domain is invisible due to dynamics. Solid-state NMR characterization of the capsid structure reveals few conformational differences between the quasi-equivalent subunits of the ACNDV capsid and an overall higher capsid structural disorder compared to HBV. Despite these differences, the capsids of ACNDV and HBV are structurally highly similar despite the 400 million years since their separation.
Crystal structure of the eukaryotic 40S ribosomal subunit in complex with initiation factor 1
Rabl, Julius (2011)
40S hnRNP particles are a novel class of nuclear biomolecular condensates
Domanski, Michal; Dedic, Emil; Escura Pérez, Maria; et al. (2022)
Nucleic Acids Research
Heterogenous nuclear ribonucleoproteins (hnRNPs) are abundant proteins implicated in various steps of RNA processing that assemble on nuclear RNA into larger complexes termed 40S hnRNP particles. Despite their initial discovery 55 years ago, our understanding of these intriguing macromolecular assemblies remains limited. Here, we report the biochemical purification of native 40S hnRNP particles and the determination of their complete protein composition by label-free quantitative mass spectrometry, identifying A-group and C-group hnRNPs as the major protein constituents. Isolated 40S hnRNP particles dissociate upon RNA digestion and can be reconstituted in vitro on defined RNAs in the presence of the individual protein components, demonstrating a scaffolding role for RNA in nucleating particle formation. Finally, we revealed their nanometer scale, condensate-like nature, promoted by intrinsically disordered regions of A-group hnRNPs. Collectively, we identify nuclear 40S hnRNP particles as novel dynamic biomolecular condensates.
Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation
Rabl, Julius; Bunker, Richard D.; Schenk, Andreas D.; et al. (2019)
Molecular Cell
In mammals, ∼100 deubiquitinases act on ∼20,000 intracellular ubiquitination sites. Deubiquitinases are commonly regarded as constitutively active, with limited regulatory and targeting capacity. The BRCA1-A and BRISC complexes serve in DNA double-strand break repair and immune signaling and contain the lysine-63 linkage-specific BRCC36 subunit that is functionalized by scaffold subunits ABRAXAS and ABRO1, respectively. The molecular basis underlying BRCA1-A and BRISC function is currently unknown. Here we show that in the BRCA1-A complex structure, ABRAXAS integrates the DNA repair protein RAP80 and provides a high-affinity binding site that sequesters the tumor suppressor BRCA1 away from the break site. In the BRISC structure, ABRO1 binds SHMT2α, a metabolic enzyme enabling cancer growth in hypoxic environments, which we find prevents BRCC36 from binding and cleaving ubiquitin chains. Our work explains modularity in the BRCC36 DUB family, with different adaptor subunits conferring diversified targeting and regulatory functions.
Single-stranded DNA binding to the transcription factor PafBC triggers the mycobacterial DNA damage response
Schilling, Charlotte M.; Zdanowicz, Rafal; Rabl, Julius; et al. (2025)
Science Advances
The DNA damage response in mycobacteria is controlled by the heterodimeric transcription factor PafBC, a member of the WYL domain-containing protein family. It has been shown that PafBC induces transcription of its regulon by reprogramming the housekeeping RNA polymerase holoenzyme to recognize PafBC-dependent promoters through sigma adaptation. However, the mechanism by which DNA damage is sensed and translated into PafBC activation has remained unclear. Here, we demonstrate that the binding of single-stranded DNA (ssDNA) to the WYL domains of PafBC activates the transcription factor. Our cryo-electron microscopy structure of full-length PafBC in its active conformation, bound to the transcription initiation complex, reveals a previously unknown mode of interaction between the ssDNA and the WYL domains. Using biochemical experiments, we show that short ssDNA fragments bind to PafBC dynamically, resulting in deactivation as ssDNA levels decrease postrepair. Our findings shed light on the mechanism linking DNA damage to PafBC activation and expand our understanding of WYL domain-containing proteins.
Crystal Structure of the Eukaryotic 40S Ribosomal Subunit in Complex with Initiation Factor 1
Rabl, Julius; Leibundgut, Marc; Ataide, Sandro F.; et al. (2011)
Science
An inhibitory segment within G-patch activators tunes Prp43-ATPase activity during ribosome assembly
Portugal-Calisto, Daniela; Geiger, Alexander Gregor; Rabl, Julius; et al. (2024)
Nature Communications
Mechanisms by which G-patch activators tune the processive multi-tasking ATP-dependent RNA helicase Prp43 (DHX15 in humans) to productively remodel diverse RNA:protein complexes remain elusive. Here, a comparative study between a herein and previously characterized activators, Tma23 and Pxr1, respectively, defines segments that organize Prp43 function during ribosome assembly. In addition to the activating G-patch, we discover an inhibitory segment within Tma23 and Pxr1, I-patch, that restrains Prp43 ATPase activity. Cryo-electron microscopy and hydrogen-deuterium exchange mass spectrometry show how I-patch binds to the catalytic RecA-like domains to allosterically inhibit Prp43 ATPase activity. Tma23 and Pxr1 contain dimerization segments that organize Prp43 into higher-order complexes. We posit that Prp43 function at discrete locations on pre-ribosomal RNA is coordinated through toggling interactions with G-patch and I-patch segments. This could guarantee measured and timely Prp43 activation, enabling precise control over multiple RNA remodelling events occurring concurrently during ribosome formation.

Publications 1 - 10 of 11

Julius Rabl

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