The biological functions of Naa10 — From amino-terminal acetylation to human disease

Dörfel, Max J.; Lyon, Gholson J.

doi:10.1016/j.gene.2015.04.085

Cited by 81 publications

(90 citation statements)

References 315 publications

(709 reference statements)

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“…They include cellcycle and mating defects as well as temperature sensitivity and perturbations of protein synthesis and degradation (27,46,64). Our finding of specific connections between the Hsp90-mediated protein homeostasis and the Nt-acetylation of proteins by NatA has revealed a major reason for the multiplicity of naa10Δ effects, given the wide range of Hsp90 functions and their impairment in the absence of NatA.…”

Section: Discussionmentioning

confidence: 86%

“…At least 60% of S. cerevisiae proteins and ∼90% of human proteins are cotranslationally and irreversibly Nt-acetylated by ribosome-associated Nt-acetylases (Fig. 1A) (45,46). In examined cases, the presence of the Nt-Ac group in a subunit of a protein complex increases the thermodynamic stability of the complex, because affinity-enhancing contacts by the Nt-Ac group cause a slower dissociation of the Nt-acetylated subunit (as compared with its unacetylated counterpart) from the rest of the complex (47)(48)(49)(50).…”

Section: Significancementioning

confidence: 99%

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Control of Hsp90 chaperone and its clients by N-terminal acetylation and the N-end rule pathway

Hyun

Varshavsky

2017

Proc. Natl. Acad. Sci. U.S.A.

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We found that the heat shock protein 90 (Hsp90) chaperone system of the yeast Saccharomyces cerevisiae is greatly impaired in naa10Δ cells, which lack the NatA N α -terminal acetylase (Nt-acetylase) and therefore cannot N-terminally acetylate a majority of normally N-terminally acetylated proteins, including Hsp90 and most of its cochaperones. Chk1, a mitotic checkpoint kinase and a client of Hsp90, was degraded relatively slowly in wild-type cells but was rapidly destroyed in naa10Δ cells by the Arg/N-end rule pathway, which recognized a C terminus-proximal degron of Chk1. Diverse proteins (in addition to Chk1) that are shown here to be targeted for degradation by the Arg/N-end rule pathway in naa10Δ cells include Kar4, Tup1, Gpd1, Ste11, and also, remarkably, the main Hsp90 chaperone (Hsc82) itself. Protection of Chk1 by Hsp90 could be overridden not only by ablation of the NatA Nt-acetylase but also by overexpression of the Arg/N-end rule pathway in wild-type cells. Split ubiquitin-binding assays detected interactions between Hsp90 and Chk1 in wild-type cells but not in naa10Δ cells. These and related results revealed a major role of Nt-acetylation in the Hsp90-mediated protein homeostasis, a strong up-regulation of the Arg/N-end rule pathway in the absence of NatA, and showed that a number of Hsp90 clients are previously unknown substrates of the Arg/N-end rule pathway.roteins called chaperones promote the in vivo protein folding and counteract misfolding, maladaptive protein aggregation, and other perturbations of proteostasis (1-4). Hsp90 is an ATPdependent chaperone system that mediates the conformational maturation and stabilization of many proteins. Referred to as Hsp90 clients, these proteins include kinases, transcriptional regulators, and many other proteins that comprise at least 20% of a cellular proteome. The diversity of Hsp90 clients and the broad range of processes that involve Hsp90 underlie its necessity for cell viability in all eukaryotes (5-11). Cochaperones of the ∼90-kDa Hsp90 comprise, in mammals, ∼30 distinct proteins. They participate in the delivery of clients to Hsp90 and contribute to related processes, including ATP hydrolysis by Hsp90 (12). Because of its ability to modulate protein conformations, the Hsp90 system can either exacerbate or counteract the fitness-reducing effects of mutations in cellular proteins. This property of Hsp90 affects the standing genetic variation and thereby influences the impact of natural selection on rates and directions of evolution (13,14).The N-end rule pathways comprise a set of proteolytic systems whose unifying feature is their ability to recognize proteins containing N-terminal (Nt) degradation signals called N-degrons, thereby causing the degradation of these proteins by the proteasome or autophagy in eukaryotes and by the proteasome-like ClpAP protease in bacteria (Fig. 1) (15-26). The main determinant of an N-degron is a destabilizing Nt-residue of a protein. Many N-degrons become active through their enzymatic Nt-acetylation, Ntformylation...

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Section: Discussionmentioning

confidence: 86%

Section: Significancementioning

confidence: 99%

Control of Hsp90 chaperone and its clients by N-terminal acetylation and the N-end rule pathway

Hyun

Varshavsky

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…These include the transcription factor Runt-related transcription factor 2 (Runx2) (11), the enzyme methionine sulfoxide reductase A (MSRA) (12), and myosin light chain kinase (MLCK) (13). These findings were surprising to us because the structures of all NATs determined to date (9, 14 -17), including Naa10 (9), contain an extended loop that seems to occlude lysine side chains within a polypeptide from lying across the active site as they do in KATs (15)(16)(17)(18). In addition, other reports demonstrating that Naa10 acetylates a lysine residue on Hif-1␣ have failed to be replicated (19 -21), making the question of whether Naa10 is able to acetylate lysine residues controversial.…”

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confidence: 99%

The N-terminal Acetyltransferase Naa10/ARD1 Does Not Acetylate Lysine Residues

Magin

March

Marmorstein

2016

Journal of Biological Chemistry

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The N-terminal acetyltransferase NatA is a heterodimeric complex consisting of a catalytic subunit (Naa10/ARD1) and an auxiliary subunit (Naa15). NatA co-translationally acetylates the N termini of a wide variety of nascent polypeptides. In addition, Naa10 can act independently to posttranslationally acetylate a distinct set of substrates, notably actin. Recent structural studies of Naa10 have also revealed the molecular basis for N-terminal acetylation specificity. Surprisingly, recent reports claim that Naa10 may also acetylate lysine residues of diverse targets, including methionine sulfoxide reductase A, myosin light chain kinase, and Runt-related transcription factor 2. Here we used recombinant proteins to reconstitute and assess lysine acetylation events catalyzed by Naa10 in vitro. We show that there is no difference in lysine acetylation of substrate proteins with or without Naa10, suggesting that the substrates may be acetylated chemically rather than enzymatically. Together, our data argue against a role for Naa10 in lysine acetylation.

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“…One branch, called the Ac/N-end rule pathway, targets proteins for degradation through their N ␣ -terminally acetylated (Nt-acetylated) residues (Fig. 1B) (5,6,13,36,56,70,71). Degradation signals and E3 Ub ligases of the Ac/N-end rule pathway are called Ac/N-degrons and Ac/N-recognins, respectively.…”

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confidence: 99%

Analyzing N-terminal Arginylation through the Use of Peptide Arrays and Degradation Assays

Wadas

Piatkov

Brower

et al. 2016

Journal of Biological Chemistry

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N␣ -terminal arginylation (Nt-arginylation) of proteins is mediated by the Ate1 arginyltransferase (R-transferase), a component of the Arg/N-end rule pathway. This proteolytic system recognizes proteins containing N-terminal degradation signals called N-degrons, polyubiquitylates these proteins, and thereby causes their degradation by the proteasome. The definitively identified ("canonical") residues that are Nt-arginylated by R-transferase are N-terminal Asp, Glu, and (oxidized) Cys. Over the last decade, several publications have suggested (i) that Ate1 can also arginylate non-canonical N-terminal residues; (ii) that Ate1 is capable of arginylating not only ␣-amino groups of N-terminal residues but also ␥-carboxyl groups of internal (non-N-terminal) Asp and Glu; and (iii) that some isoforms of Ate1 are specific for substrates bearing N-terminal Cys residues. In the present study, we employed arrays of immobilized 11-residue peptides and pulse-chase assays to examine the substrate specificity of mouse R-transferase. We show that amino acid sequences immediately downstream of a substrate's canonical (Nt-arginylatable) N-terminal residue, particularly a residue at position 2, can affect the rate of Nt-arginylation by R-transferase and thereby the rate of degradation of a substrate protein. We also show that the four major isoforms of mouse R-transferase have similar Nt-arginylation specificities in vitro, contrary to the claim about the specificity of some Ate1 isoforms for N-terminal Cys. In addition, we found no evidence for a significant activity of the Ate1 R-transferase toward previously invoked non-canonical N-terminal or internal amino acid residues. Together, our results raise technical concerns about earlier studies that invoked non-canonical arginylation specificities of Ate1.The N-end rule pathway is a set of intracellular proteolytic systems whose unifying feature is the ability to recognize and polyubiquitylate proteins containing N-terminal (Nt) 2 degradation signals called N-degrons, thereby causing the processive degradation of these proteins by the proteasome (Fig. 1, A and B) (1-13). Recognition components of the N-end rule pathway are called N-recognins. In eukaryotes, N-recognins are E3 ubiquitin (Ub) ligases that can target N-degrons. Some N-recognins contain several substrate-binding sites and thereby can recognize (bind to) not only N-degrons but also specific internal (non-N-terminal) degradation signals (Fig. 1A) (14 -18). The main determinant of a protein's N-degron is either an unmodified or chemically modified N-terminal residue. Another determinant of an N-degron is an internal Lys residue(s). It functions as a site of protein polyubiquitylation, is often engaged stochastically (in competition with other "eligible" lysines), and tends to be located in a conformationally disordered region (2,9,19,20). Bacteria also contain the N-end rule pathway, but Ub-independent versions of it (21-26).Regulated degradation of proteins and their natural fragments by the N-end rule pathway has been s...

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The biological functions of Naa10 — From amino-terminal acetylation to human disease

Cited by 81 publications

References 315 publications

Control of Hsp90 chaperone and its clients by N-terminal acetylation and the N-end rule pathway

Control of Hsp90 chaperone and its clients by N-terminal acetylation and the N-end rule pathway

The N-terminal Acetyltransferase Naa10/ARD1 Does Not Acetylate Lysine Residues

Analyzing N-terminal Arginylation through the Use of Peptide Arrays and Degradation Assays

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