8CCW

Crystal structure of human Sirt3 in complex with an acetylated HIV1 Tat-46-54 substrate peptide

Summary for 8CCW

• Entry DOI: 10.2210/pdb8ccw/pdb
• Descriptor: NAD-dependent protein deacetylase sirtuin-3, mitochondrial, Protein Tat, ZINC ION, ... (4 entities in total)
• Functional Keywords: sirtuin, substrate, hiv, tat, complex, signaling protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 32629.91

Authors

Adolph, R.S.,Steegborn, C. (deposition date: 2023-01-27, release date: 2023-05-10, Last modification date: 2024-02-07)

Primary citation

Adolph, R.S.,Beck, E.,Schweimer, K.,Di Fonzo, A.,Weyand, M.,Rosch, P.,Wohrl, B.M.,Steegborn, C.
Molecular Mechanism of Sirtuin 1 Inhibition by Human Immunodeficiency Virus 1 Tat Protein.
Life, 13:-, 2023

PubMed Abstract: Sirtuins are NAD-dependent protein lysine deacylases implicated in metabolic regulation and aging-related dysfunctions. The nuclear isoform Sirt1 deacetylates histones and transcription factors and contributes, e.g., to brain and immune cell functions. Upon infection by human immunodeficiency virus 1 (HIV1), Sirt1 deacetylates the viral transactivator of transcription (Tat) protein to promote the expression of the viral genome. Tat, in turn, inhibits Sirt1, leading to the T cell hyperactivation associated with HIV infection. Here, we describe the molecular mechanism of Tat-dependent sirtuin inhibition. Using Tat-derived peptides and recombinant Tat protein, we mapped the inhibitory activity to Tat residues 34-59, comprising Tat core and basic regions and including the Sirt1 deacetylation site Lys50. Tat binds to the sirtuin catalytic core and inhibits Sirt1, Sirt2, and Sirt3 with comparable potencies. Biochemical data and crystal structures of sirtuin complexes with Tat peptides reveal that Tat exploits its intrinsically extended basic region for binding to the sirtuin substrate binding cleft through substrate-like β-strand interactions, supported by charge complementarity. Tat Lys50 is positioned in the sirtuin substrate lysine pocket, although binding and inhibition do not require prior acetylation and rely on subtle differences to the binding of regular substrates. Our results provide mechanistic insights into sirtuin regulation by Tat, improving our understanding of physiological sirtuin regulation and the role of this interaction during HIV1 infection.

PubMed: 37109478
DOI: 10.3390/life13040949

Experimental method

X-RAY DIFFRACTION (1.65 Å)