Actin maturation requires the ACTMAP/C19orf54 protease

Haahr, Peter; Galli, Ricardo A.; Hengel, Lisa G. van den; Bleijerveld, Onno B.; Kazokaitė-Adomaitienė, Justina; Song, Ji‐Ying; Kroese, Lona J.; Krimpenfort, Paul; Baltissen, Marijke P; Vermeulen, Michiel; Ottenheijm, Coen A.C.; Brummelkamp, Thijn R.

doi:10.1126/science.abq5082

Cited by 13 publications

(5 citation statements)

References 33 publications

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“…The class I actins are presumed to be co-translationally acetylated by NatB ( 17 ) before the Nt-Ac-Met is removed by ACTMAP, the recently discovered actin maturation protease ( 18 ). This exposes the neo-N-terminus at Asp2/Glu2 and allows post-translational Nt-acetylation by NAA80 ( 8 ).…”

Section: Resultsmentioning

confidence: 99%

“…The class II actins (Met-Cys-Asp/Glu-…) are presumed to be substrates of MetAP1/2, removing the iMet and exposing the neo-N-terminus at Cys2 ( 19 ). This is then potentially Nt-acetylated by NatA (co-translationally) before the Cys2 is removed by ACTMAP ( 18 ), exposing the Nt-amine group of acidic Asp3/Glu3 as the acceptor of NAA80-mediated acetylation ( 20 ).…”

Section: Resultsmentioning

confidence: 99%

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Naa80 is required for actin N-terminal acetylation and normal hearing in zebrafish

Ree,

Lin,

Sti Dahl

et al. 2024

Preprint

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Actin is a key component of the cytoskeleton of eukaryotic cells and is involved in numerous cellular functions. In animal cells, actins are uniquely N-terminally processed by a dedicated enzyme machinery to generate their mature acidic and acetylated forms. The final step of this maturation process involves N-terminal acetylation, a reaction catalyzed by NAA80 in humans. In human cell lines, N-terminal acetylation of actin plays a crucial role in maintaining normal cytoskeletal dynamics and cell motility. The physiological impact of actin N-terminal acetylation remains to be defined. Here, we developed a zebrafishnaa80knockout model and established that zNaa80 acetylates both muscle and non-muscle actinsin vivo. Ourin vitroinvestigation of purified zNaa80 unveiled a clear preference for acetylating N-termini derived from actins. Interestingly, zebrafish lacking actin N-terminal acetylation were viable and exhibited normal development, morphology and behaviour. In contrast, human individuals carrying pathogenic actin variants may present with hypotonia and hearing impairment. While zebrafish depleted fornaa80did not display any obvious muscle defects or abnormal muscle tissue, we found that they have abnormal inner ear development such as small otoliths and impaired response to sound stimuli. In sum, we have defined that zebrafish Naa80 N-terminally acetylates actinsin vitroandin vivoand that actin N-terminal acetylation is essential for normal hearingin vivo.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Naa80 is required for actin N-terminal acetylation and normal hearing in zebrafish

Ree,

Lin,

Sti Dahl

et al. 2024

Preprint

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“…Gene-trap mutagenesis of HAP1 cell lines were carried out as described 59 . Briefly, a BFP-containing variant of gene-trap retrovirus was generated in low passage HEK293T cells by co-transfection of gene-trap vector, retroviral packaging plasmids Gag-pol and VsVg, and pAdvantage (Promega).…”

Section: Methodsmentioning

confidence: 99%

Concerted SUMO-targeted ubiquitin ligase activities of TOPORS and RNF4 are essential for stress management and cell proliferation

Liu,

Ackermann,

Hoffmann

et al. 2023

Preprint

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SummaryProtein SUMOylation provides a principal driving force for cellular stress responses including DNA-protein crosslink (DPC) repair and arsenic-induced PML body degradation. In genome-scale screens, we identified the human E3 ligase TOPORS as a key effector of SUMO-dependent DPC resolution. We demonstrate that TOPORS promotes DPC repair by functioning as a SUMO-targeted ubiquitin ligase (STUbL) for DPCs, combining ubiquitin ligase activity through its RING domain with poly-SUMO chain binding via a cluster of SUMO-interacting motifs, analogous to the STUbL RNF4. Surprisingly, the STUbL activities of TOPORS and RNF4 are both required for SUMO-dependent DPC repair, PML degradation and other stress responses, making overlapping and distinct contributions to ubiquitin chain formation on SUMOylated targets to enable p97/VCP unfoldase recruitment. Combined loss of TOPORS and RNF4 is synthetic lethal even in unstressed cells, leading to defective clearance of SUMOylated proteins from chromatin accompanied by cell cycle arrest and apoptosis. Together, our findings establish TOPORS as a novel STUbL whose concerted action with RNF4 defines a general mechanistic principle in crucial cellular processes governed by direct SUMO-ubiquitin crosstalk.HighlightsThe RING E3 ligase TOPORS is required for SUMO-dependent DPC repairTOPORS is a novel SUMO-targeted ubiquitin ligase (STUbL)TOPORS promotes multiple STUbL-driven processes in conjunction with RNF4Combined TOPORS and RNF4 loss is synthetic lethal in human cells

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“…The mutational index (MI) for subunits from the NELF complex (NELFA, NEFLB, NELFCD, NELFE) was plotted for the current LAD5 and LAD6 screens and 15 additional FACS-based haploid screens previously conducted in HAP1 cells using the indicated readouts (blue, negative regulator; orange, positive regulator; grey, not significant) (Brockmann et al ., 2017; Haahr et al , 2022; Jongsma et al , 2021; Logtenberg et al , 2019; Mazouzi et al ., 2023; Mezzadra et al , 2017; Nieuwenhuis et al , 2017). …”

Section: Supplementary Figuresmentioning

confidence: 99%

Chromatin protein complexes involved in gene repression in lamina-associated domains

Manzo,

Mazouzi,

Leemans

et al. 2024

Preprint

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Lamina-associated domains (LADs) are large chromatin regions that are associated with the nuclear lamina (NL) and form a repressive environment for transcription. The molecular play-ers that mediate gene repression in LADs are currently unknown. Here we performed FACS-based whole-genome genetic screens in human cells using LAD-integrated fluorescent re-porters to identify such regulators. Surprisingly, the screen identified very few NL proteins, but revealed roles for dozens of known chromatin regulators. Among these are the negative elongation factor (NELF) complex and interacting factors involved in RNA polymerase paus-ing, suggesting that regulation of transcription elongation is a mechanism to repress tran-scription in LADs. Furthermore, the chromatin remodeler complex BAF and the activation complex Mediator can work both as activators and repressors in LADs, depending on the local context and possibly rewiring of heterochromatin. Our data clearly emphasize that the fundamental regulatory steps of the transcription process and chromatin remodeling factors, rather than interaction with NL proteins, play a major role in the regulation of transcription within LADs.

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Actin maturation requires the ACTMAP/C19orf54 protease

Cited by 13 publications

References 33 publications

Naa80 is required for actin N-terminal acetylation and normal hearing in zebrafish

Naa80 is required for actin N-terminal acetylation and normal hearing in zebrafish

Concerted SUMO-targeted ubiquitin ligase activities of TOPORS and RNF4 are essential for stress management and cell proliferation

Chromatin protein complexes involved in gene repression in lamina-associated domains

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