Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition
SIRT1 is the most extensively studied human sirtuin with a broad spectrum of endogenous targets. It has been implicated in the regulation of a myriad of cellular events, such as gene transcription, mitochondria biogenesis, insulin secretion as well as glucose and lipid metabolism. From a mechanistic...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Biomolecules |
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| Online Access: | https://www.mdpi.com/2218-273X/11/2/312 |
| _version_ | 1797396055827939328 |
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| author | Stacia Rymarchyk Wenjia Kang Yana Cen |
| author_facet | Stacia Rymarchyk Wenjia Kang Yana Cen |
| author_sort | Stacia Rymarchyk |
| collection | DOAJ |
| description | SIRT1 is the most extensively studied human sirtuin with a broad spectrum of endogenous targets. It has been implicated in the regulation of a myriad of cellular events, such as gene transcription, mitochondria biogenesis, insulin secretion as well as glucose and lipid metabolism. From a mechanistic perspective, nicotinamide (NAM), a byproduct of a sirtuin-catalyzed reaction, reverses a reaction intermediate to regenerate NAD<sup>+</sup> through “base exchange”, leading to the inhibition of the forward deacetylation. NAM has been suggested as a universal sirtuin negative regulator. Sirtuins have evolved different strategies in response to NAM regulation. Here, we report the detailed kinetic analysis of SIRT1-catalyzed reactions using endogenous substrate-based synthetic peptides. A novel substrate-dependent sensitivity of SIRT1 to NAM inhibition was observed. Additionally, SIRT1 demonstrated pH-dependent deacetylation with normal solvent isotope effects (SIEs), consistent with proton transfer in the rate-limiting step. Base exchange, in contrast, was insensitive to pH changes with no apparent SIEs, indicative of lack of proton transfer in the rate-limiting step. Consequently, NAM inhibition was attenuated at a high pH in proteated buffers. Our study provides new evidence for “activation by de-repression” as an effective sirtuin activation strategy. |
| first_indexed | 2024-03-09T00:45:47Z |
| format | Article |
| id | doaj.art-875d86bcdba14889977d94104c267269 |
| institution | Directory Open Access Journal |
| issn | 2218-273X |
| language | English |
| last_indexed | 2024-03-09T00:45:47Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Biomolecules |
| spelling | doaj.art-875d86bcdba14889977d94104c2672692023-12-11T17:33:16ZengMDPI AGBiomolecules2218-273X2021-02-0111231210.3390/biom11020312Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide InhibitionStacia Rymarchyk0Wenjia Kang1Yana Cen2Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Colchester, VT 05446, USADepartment of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23219, USADepartment of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23219, USASIRT1 is the most extensively studied human sirtuin with a broad spectrum of endogenous targets. It has been implicated in the regulation of a myriad of cellular events, such as gene transcription, mitochondria biogenesis, insulin secretion as well as glucose and lipid metabolism. From a mechanistic perspective, nicotinamide (NAM), a byproduct of a sirtuin-catalyzed reaction, reverses a reaction intermediate to regenerate NAD<sup>+</sup> through “base exchange”, leading to the inhibition of the forward deacetylation. NAM has been suggested as a universal sirtuin negative regulator. Sirtuins have evolved different strategies in response to NAM regulation. Here, we report the detailed kinetic analysis of SIRT1-catalyzed reactions using endogenous substrate-based synthetic peptides. A novel substrate-dependent sensitivity of SIRT1 to NAM inhibition was observed. Additionally, SIRT1 demonstrated pH-dependent deacetylation with normal solvent isotope effects (SIEs), consistent with proton transfer in the rate-limiting step. Base exchange, in contrast, was insensitive to pH changes with no apparent SIEs, indicative of lack of proton transfer in the rate-limiting step. Consequently, NAM inhibition was attenuated at a high pH in proteated buffers. Our study provides new evidence for “activation by de-repression” as an effective sirtuin activation strategy.https://www.mdpi.com/2218-273X/11/2/312SIRT1epigeneticsdeacetylationNAM inhibitionbase exchangesolvent isotope effect |
| spellingShingle | Stacia Rymarchyk Wenjia Kang Yana Cen Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition Biomolecules SIRT1 epigenetics deacetylation NAM inhibition base exchange solvent isotope effect |
| title | Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition |
| title_full | Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition |
| title_fullStr | Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition |
| title_full_unstemmed | Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition |
| title_short | Substrate-Dependent Sensitivity of SIRT1 to Nicotinamide Inhibition |
| title_sort | substrate dependent sensitivity of sirt1 to nicotinamide inhibition |
| topic | SIRT1 epigenetics deacetylation NAM inhibition base exchange solvent isotope effect |
| url | https://www.mdpi.com/2218-273X/11/2/312 |
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