Acetylation within the First 17 Residues of Huntingtin Exon 1 Alters Aggregation and Lipid Binding

Chaibva, Maxmore; Jawahery, Sudi; Pilkington, Albert W.; Arndt, James R.; Sarver, Olivia; Valentine, Stephen J.; Matysiak, Silvina; Legleiter, Justin

doi:10.1016/j.bpj.2016.06.018

Cited by 63 publications

(96 citation statements)

References 115 publications

(217 reference statements)

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“…246 Proteomic mapping by MS demonstrated that K9 is substantially acetylated in mammalian cell lysates, 233 and this residue is preferentially chemically acetylated in vitro. 247 Interestingly, acetylation of N17 reduces aggregation into fibrils while promoting the formation of large oligomeric species. 247 Acetylation of N17 also decreases htt’s affinity for lipid membranes, and computational studies suggested that K9 may play a key role in the initial binding of N17 to lipids.…”

Section: Post-translational Modifications Impact Aggregation and Toximentioning

confidence: 99%

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Proteins Containing Expanded Polyglutamine Tracts and Neurodegenerative Disease

et al. 2017

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Several hereditary neurological and neuromuscular diseases are caused by an abnormal expansion of trinucleotide repeats. To date, there have been ten of these trinucleotide repeat disorders associated with an expansion of the codon CAG encoding glutamine (Q). For these polyglutamine (polyQ) diseases, there is a critical threshold length of the CAG repeat required for disease, and further expansion beyond this threshold is correlated with age of onset and symptom severity. PolyQ expansion in the translated proteins promotes their self-assembly into a variety of oligomeric and fibrillar aggregate species that accumulate into the hallmark proteinaceous inclusion bodies associated with each disease. Here, we review aggregation mechanisms of proteins with expanded polyQ-tracts, structural consequences of expanded polyQ ranging from monomers to fibrillar aggregates, the impact of protein context and post translational modifications on aggregation, and a potential role for lipids membranes in aggregation. As the pathogenic mechanisms that underlie these disorders are often classified as either a gain of toxic function or loss of normal protein function, some toxic mechanisms associated with mutant polyQ tracts will also be discussed.

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Section: Post-translational Modifications Impact Aggregation and Toximentioning

confidence: 99%

“…247 Acetylation of N17 also decreases htt’s affinity for lipid membranes, and computational studies suggested that K9 may play a key role in the initial binding of N17 to lipids. 247 …”

Section: Post-translational Modifications Impact Aggregation and Toximentioning

confidence: 99%

Proteins Containing Expanded Polyglutamine Tracts and Neurodegenerative Disease

et al. 2017

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“…[11] Chaibva et al reported that acetylation of Httex1 retards fibrils formation in vitro. [9] However, it is noteworthy that their findings were based on nonselective chemical acetylation of all lysine residues in a model peptide of Httex1 lacking the last 39 C-terminal residues and containing two non-native lysines residues which were also partially acetylated. To investigate the effect of lysine acetylation on Httex1 aggregation, we produced both WT (23Q) and mutant (43Q) Httex1 acetylated at single lysine residues (AcK6, AcK9, and AcK15).…”

Section: Main Textmentioning

confidence: 99%

“…Although acetylation of lysine residues within Nt17 has been proposed to play a role in regulating its association with membranes, [9] only K9 was reported to be acetylated in HEK cells [10] and was proposed to play an important role in Htt clearance. [11] Chaibva et al reported that acetylation of Httex1 retards fibrils formation in vitro.…”

Section: Main Textmentioning

confidence: 99%

Mutant Exon1 Huntingtin Aggregation is Regulated by T3 Phosphorylation‐Induced Structural Changes and Crosstalk between T3 Phosphorylation and Acetylation at K6

et al. 2017

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Herein, we used protein semisynthesis to investigate, for the first time, the effect of lysine acetylation and phosphorylation, as well as the crosstalk between these modifications on the structure and aggregation of mutant huntingtin exon1 (Httex1). Our results demonstrate that phosphorylation at T3 stabilizes the α-helical conformation of the N-terminal 17 amino acids (Nt17) and significantly inhibits the aggregation of mutant Httex1. Acetylation of single lysine residues, K6, K9 or K15, had no effect on Httex1 aggregation. Interestingly, acetylation at K6, but not at K9 or K15, reversed the inhibitory effect of T3 phosphorylation. Together, our results provide novel insight into the role of Nt17 posttranslational modifications in regulating the structure and aggregation of Httex1 and suggest that its aggregation and possibly its function(s) are controlled by regulatory mechanisms involving crosstalk between different PTMs. Main textSeveral lines of evidence suggest that the first N-terminal 17 amino acids of the Huntingtin protein (Htt) play important roles in modulating Htt structure, oligomerization, fibrils formation, membrane binding, subcellular localization and interactions with other proteins. [1] This, combined with the fact that this short N-terminal sequence harbors several residues that are subjected to diverse posttranslational modifications (PTMs), including phosphorylation, acetylation, ubiquitination and sumoylation (Scheme S1-A in the Supporting Information), suggests that PTMs may serve as reversible molecular switches for regulating Htt structure, interactome, cellular properties and toxicity. [2] However, the lack of knowledge about the enzymes involved in regulating these modifications has made it difficult to decipher their role in regulating the function(s) of Htt in health and disease.To address these limitations and enable deciphering of the Nt17 PTM code, our group has pursued the development of semisynthetic strategies that permit site-specific introduction of single or multiple PTMs within Nt17 of Huntingtin exon 1 (Httex1). Recently, we reported a semisynthetic strategy that permits site-specific phosphorylation at T3.[3] However, this strategy suffered from several limitations and was only suitable for introducing PTMs in the first N-terminal 9 residues of wild-type Httex1 (≤23 glutamine residues) (Scheme S2). [3] To allow investigations of all Nt17 PTMs, we developed and optimized two new modular semisynthetic protocols that permit the generation of wild-type and for the first time mutant Httex1 (mHttex1) proteins containing single or multiple PTMs (Scheme S3). The first strategy (Scheme S3-A) is only suitable for introducing PTMs in the N-terminal 9 residues of Httex1, whereas the second strategy allows the investigation of all the PTMs within the Nt17 domain. Additionally, the optimized conditions enabled the semisynthesis of mutant Httex1 (full details about these semisynthetic strategies are given in the Supporting Information). This optimized strategy enabled us, for...

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“…The enhanced toxicity of mHTT lacking its N17 domain may be due to the fact that this domain modulates HTT's interaction with multiple chaperone proteins that affect the size, density, and location of HTT aggregates through acetylation, ubiquitination, and sumoylation of this domain [118,120,121].…”

Section: Wild Type Huntington Functionsmentioning

confidence: 99%

Structure/Function Analysis of the Huntingtin N-terminus Encoded by Htt Exon 1 Using Knock-In Mouse Models

André¹

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Huntington's disease (HD) is a neurodegenerative disorder that effects up to 1 in every 10,000 people and it is caused by an expansion of the polyglutamine (polyQ) stretch within the Huntingtin (HTT) protein [1]. The HTT polyQ in mammals is flanked by a highly conserved 17 amino acid N-terminal domain (N17), and a proline-rich region (PRR) [2][3][4]. The PRR is a binding site for many , and the N17 domain regulates several normal HTT functions, including HTT's ability to associate with membranes and organelles [8,9]. iv Acknowledgements I would first and foremost like to thank Scott Zeitlin and Jeh-Ping Liu for their scientific guidance, technical expertise and continual support. Thank you for always pushing me to be a better scientist, and for your patience during the times when things were not working out the way we wanted. I would also like to thank my committee

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Acetylation within the First 17 Residues of Huntingtin Exon 1 Alters Aggregation and Lipid Binding

Cited by 63 publications

References 115 publications

Proteins Containing Expanded Polyglutamine Tracts and Neurodegenerative Disease

Proteins Containing Expanded Polyglutamine Tracts and Neurodegenerative Disease

Mutant Exon1 Huntingtin Aggregation is Regulated by T3 Phosphorylation‐Induced Structural Changes and Crosstalk between T3 Phosphorylation and Acetylation at K6

Structure/Function Analysis of the Huntingtin N-terminus Encoded by Htt Exon 1 Using Knock-In Mouse Models

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