Maturation of NAA20 Aminoterminal End Is Essential to Assemble NatB N-Terminal Acetyltransferase Complex

Lasa, Marta; Neri, Leire; Carte, Beatriz; Gázquez, Cristina; Aragón, Tomás; Aldabe, Rafael

doi:10.1016/j.jmb.2020.09.010

Cited by 4 publications

(4 citation statements)

References 32 publications

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“…While cell-permeable inhibitors targeting NAA25 or the NatB complex are currently unavailable, we decided to repurpose currently available METAP2 inhibitors to indirectly down-regulate αSyn levels in iNeurons by modulating NatB subunit expression. In alignment with previous findings ( 61 ), in which METAP2 was demonstrated to be a central regulator of NatB subunit expression and complex formation, we hypothesized that silencing METAP2 should negatively affect NAA25 expression levels, which, in turn, should attenuate levels of αSyn. First, we confirmed that knocking down METAP2 resulted in the reduction of NAA25 levels in iNeurons using a Western blot (Fig.…”

Section: Resultssupporting

confidence: 75%

“…Consistent with our screen results, down-regulation of NAA15 and METAP2 resulted in a decrease of αSyn in iNeurons. We decided to further explore the mechanism of METAP2 regulation of αSyn for two main reasons: (i) METAP2 is required for the proper assembly of the NatB complex ( 61 ), and (ii) several METAP2 inhibitors have been used in clinical trials, including TNP470, that can penetrate the blood-brain barrier ( 62 ). While cell-permeable inhibitors targeting NAA25 or the NatB complex are currently unavailable, we decided to repurpose currently available METAP2 inhibitors to indirectly down-regulate αSyn levels in iNeurons by modulating NatB subunit expression.…”

Section: Resultsmentioning

confidence: 99%

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Sequential CRISPR screening reveals partial NatB inhibition as a strategy to mitigate alpha-synuclein levels in human neurons

Santhosh Kumar,

Naseri,

Pather

et al. 2024

Sci. Adv.

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Alpha-synuclein (αSyn) protein levels correlate with the risk and severity of Parkinson’s disease and related neurodegenerative diseases. Lowering αSyn is being actively investigated as a therapeutic modality. Here, we systematically map the regulatory network that controls endogenous αSyn using sequential CRISPR-knockout and -interference screens in an αSyn gene ( SNCA )–tagged cell line and induced pluripotent stem cell–derived neurons (iNeurons). We uncover αSyn modifiers at multiple regulatory layers, with amino-terminal acetyltransferase B (NatB) enzymes being the most potent endogenous αSyn modifiers in both cell lines. Amino-terminal acetylation protects the cytosolic αSyn from rapid degradation by the proteasome in a Ube2w-dependent manner. Moreover, we show that pharmacological inhibition of methionyl-aminopeptidase 2, a regulator of NatB complex formation, attenuates endogenous αSyn in iNeurons carrying SNCA triplication. Together, our study reveals several gene networks that control endogenous αSyn, identifies mechanisms mediating the degradation of nonacetylated αSyn, and illustrates potential therapeutic pathways for decreasing αSyn levels in synucleinopathies.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Sequential CRISPR screening reveals partial NatB inhibition as a strategy to mitigate alpha-synuclein levels in human neurons

Santhosh Kumar,

Naseri,

Pather

et al. 2024

Sci. Adv.

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“…Previous works indicated that NAA20 is rapidly degraded in the absence of its accessory subunit, NAA25 4 and this interaction involves the Nt amino acids of NAA20 11 . Thus, even though we were not able to detect a significant destabilization of overexpressed NAA20‐Leu4Pro, it is possible that endogenous NAA20‐Leu4Pro is less stable than NAA20‐WT.…”

Section: Discussioncontrasting

confidence: 79%

Novel biallelic variants expand the phenotype of NAA20‐related syndrome

et al. 2023

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NAA20 is the catalytic subunit of the NatB complex, which is responsible for N‐terminal acetylation of approximately 20% of the human proteome. Recently, pathogenic biallelic variants in NAA20 were associated with a novel neurodevelopmental disorder in five individuals with limited clinical information. We report two sisters harboring compound heterozygous variant (c.100C>T (p.Gln34Ter) and c.11T>C p.(Leu4Pro)) in the NAA20 gene, identified by exome sequencing. In vitro studies showed that the missense variant p.Leu4Pro resulted in a reduction of NAA20 catalytic activity due to weak coupling with the NatB auxiliary subunit. In addition, unpublished data of the previous families were reported, outlining the core phenotype of the NAA20‐related disorder mostly characterized by cognitive impairment, microcephaly, ataxia, brain malformations, dysmorphism and variable occurrence of cardiac defect and epilepsy. Remarkably, our two patients featured epilepsy onset in adolescence suggesting this may be a part of syndrome evolution. Functional studies are needed to better understand the complexity of NAA20 variants pathogenesis as well as of other genes linked to N‐terminal acetylation.

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“…Another contact to the ES27a tip is established by the TPR-helices of the Naa25-1 C-terminus (α34-α36). In this conformation, the catalytic subunit Naa20-1 faces towards the exit tunnel, but density is only visible at the well-conserved contact interface with Naa25-1 (including highly conserved Thr2 and Glu48 of Naa20 and Arg296 of Naa25) [ 40 ], indicating that it is largely delocalized.…”

Section: Resultsmentioning

confidence: 99%

The dynamic architecture of Map1- and NatB-ribosome complexes coordinates the sequential modifications of nascent polypeptide chains

et al. 2023

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Cotranslational modification of the nascent polypeptide chain is one of the first events during the birth of a new protein. In eukaryotes, methionine aminopeptidases (MetAPs) cleave off the starter methionine, whereas N-acetyl-transferases (NATs) catalyze N-terminal acetylation. MetAPs and NATs compete with other cotranslationally acting chaperones, such as ribosome-associated complex (RAC), protein targeting and translocation factors (SRP and Sec61) for binding sites at the ribosomal tunnel exit. Yet, whereas well-resolved structures for ribosome-bound RAC, SRP and Sec61, are available, structural information on the mode of ribosome interaction of eukaryotic MetAPs or of the five cotranslationally active NATs is only available for NatA. Here, we present cryo-EM structures of yeast Map1 and NatB bound to ribosome-nascent chain complexes. Map1 is mainly associated with the dynamic rRNA expansion segment ES27a, thereby kept at an ideal position below the tunnel exit to act on the emerging substrate nascent chain. For NatB, we observe two copies of the NatB complex. NatB-1 binds directly below the tunnel exit, again involving ES27a, and NatB-2 is located below the second universal adapter site (eL31 and uL22). The binding mode of the two NatB complexes on the ribosome differs but overlaps with that of NatA and Map1, implying that NatB binds exclusively to the tunnel exit. We further observe that ES27a adopts distinct conformations when bound to NatA, NatB, or Map1, together suggesting a contribution to the coordination of a sequential activity of these factors on the emerging nascent chain at the ribosomal exit tunnel.

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Maturation of NAA20 Aminoterminal End Is Essential to Assemble NatB N-Terminal Acetyltransferase Complex

Cited by 4 publications

References 32 publications

Sequential CRISPR screening reveals partial NatB inhibition as a strategy to mitigate alpha-synuclein levels in human neurons

Sequential CRISPR screening reveals partial NatB inhibition as a strategy to mitigate alpha-synuclein levels in human neurons

Novel biallelic variants expand the phenotype of NAA20‐related syndrome

The dynamic architecture of Map1- and NatB-ribosome complexes coordinates the sequential modifications of nascent polypeptide chains

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