Structure-based mechanism of ADP-ribosylation by sirtuins.
Sirtuins comprise a family of enzymes found in all organisms, where they play a role in diverse processes including transcriptional silencing, aging, regulation of transcription, and metabolism. The predominant reaction catalyzed by these enzymes is NAD(+)-dependent lysine deacetylation, although some sirtuins exhibit a weaker ADP-ribosyltransferase activity. Although the Sir2 deacetylation mechanism is well established, much less is known about the Sir2 ADP-ribosylation reaction. We have studied the ADP-ribosylation activity of a bacterial sirtuin, Sir2Tm, and show that acetylated peptides containing arginine or lysine 2 residues C-terminal to the acetyl lysine, the +2 position, are preferentially ADP-ribosylated at the +2 residue. A structure of Sir2Tm bound to the acetylated +2 arginine peptide shows how this arginine could enter the active site and react with a deacetylation reaction intermediate to yield an ADP-ribosylated peptide. The new biochemical and structural studies presented here provide mechanistic insights into the Sir2 ADP-ribosylation reaction and will aid in identifying substrates of this reaction.
Hawse
William F
WF
Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Wolberger
Cynthia
C
D036002:ADP Ribose Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000107:Acetylation; D000246:Adenosine Diphosphate Ribose / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D008239:Lysine / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D037761:Sirtuins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D020124:Thermotoga maritima / Q000201:enzymology; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D010455:Peptides; D016159:Tumor Suppressor Protein p53; D000246:Adenosine Diphosphate Ribose; D001120:Arginine; D036002:ADP Ribose Transferases; D037761:Sirtuins; D008239:Lysine