| Structural highlights
Disease
[SAHH_HUMAN] Defects in AHCY are the cause of hypermethioninemia with S-adenosylhomocysteine hydrolase deficiency (HMAHCHD) [MIM:613752]. A metabolic disorder characterized by hypermethioninemia associated with failure to thrive, mental and motor retardation, facial dysmorphism with abnormal hair and teeth, and myocardiopathy.[1] [2] [3] [4]
Function
[SAHH_HUMAN] Adenosylhomocysteine is a competitive inhibitor of S-adenosyl-L-methionine-dependent methyl transferase reactions; therefore adenosylhomocysteinase may play a key role in the control of methylations via regulation of the intracellular concentration of adenosylhomocysteine.[5]
Publication Abstract from PubMed
S-adenosylhomocysteine hydrolase (SAHH) is an NAD+-dependent tetrameric enzyme that catalyzes the breakdown of S-adenosylhomocysteine to adenosine and homocysteine and is important in cell growth and the regulation of gene expression. Loss of SAHH function can result in global inhibition of cellular methyltransferase enzymes because of high levels of S-adenosylhomocysteine. Prior proteomics studies have identified two SAHH acetylation sites at Lys-401 and Lys-408 but the impact of these post-translational modifications has not yet been determined. Here we use expressed protein ligation to produce semisynthetic SAHH acetylated at Lys-401 and Lys-408 and show that modification of either position negatively impacts the catalytic activity of SAHH. X-ray crystal structures of 408-acetylated-SAHH and dually acetylated SAHH have been determined and reveal perturbations in the C-terminal hydrogen bonding patterns, a region of the protein important for NAD+ binding. These crystal structures along with mutagenesis data suggest that such hydrogen bond perturbations are responsible for SAHH catalytic inhibition by acetylation. These results suggest how increased acetylation of SAHH may globally influence cellular methylation patterns.
Regulation of S-Adenosylhomocysteine Hydrolase by Lysine Acetylation.,Wang Y, Kavran JM, Chen Z, Karukurichi KR, Leahy DJ, Cole PA J Biol Chem. 2014 Sep 23. pii: jbc.M114.597153. PMID:25248746[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Baric I, Fumic K, Glenn B, Cuk M, Schulze A, Finkelstein JD, James SJ, Mejaski-Bosnjak V, Pazanin L, Pogribny IP, Rados M, Sarnavka V, Scukanec-Spoljar M, Allen RH, Stabler S, Uzelac L, Vugrek O, Wagner C, Zeisel S, Mudd SH. S-adenosylhomocysteine hydrolase deficiency in a human: a genetic disorder of methionine metabolism. Proc Natl Acad Sci U S A. 2004 Mar 23;101(12):4234-9. Epub 2004 Mar 15. PMID:15024124 doi:10.1073/pnas.0400658101
- ↑ Buist NR, Glenn B, Vugrek O, Wagner C, Stabler S, Allen RH, Pogribny I, Schulze A, Zeisel SH, Baric I, Mudd SH. S-adenosylhomocysteine hydrolase deficiency in a 26-year-old man. J Inherit Metab Dis. 2006 Aug;29(4):538-45. Epub 2006 May 30. PMID:16736098 doi:10.1007/s10545-006-0240-0
- ↑ Vugrek O, Beluzic R, Nakic N, Mudd SH. S-adenosylhomocysteine hydrolase (AHCY) deficiency: two novel mutations with lethal outcome. Hum Mutat. 2009 Apr;30(4):E555-65. doi: 10.1002/humu.20985. PMID:19177456 doi:10.1002/humu.20985
- ↑ Grubbs R, Vugrek O, Deisch J, Wagner C, Stabler S, Allen R, Baric I, Rados M, Mudd SH. S-adenosylhomocysteine hydrolase deficiency: two siblings with fetal hydrops and fatal outcomes. J Inherit Metab Dis. 2010 Dec;33(6):705-13. doi: 10.1007/s10545-010-9171-x. Epub , 2010 Sep 18. PMID:20852937 doi:10.1007/s10545-010-9171-x
- ↑ Yang X, Hu Y, Yin DH, Turner MA, Wang M, Borchardt RT, Howell PL, Kuczera K, Schowen RL. Catalytic strategy of S-adenosyl-L-homocysteine hydrolase: transition-state stabilization and the avoidance of abortive reactions. Biochemistry. 2003 Feb 25;42(7):1900-9. PMID:12590576 doi:https://dx.doi.org/10.1021/bi0262350
- ↑ Wang Y, Kavran JM, Chen Z, Karukurichi KR, Leahy DJ, Cole PA. Regulation of S-Adenosylhomocysteine Hydrolase by Lysine Acetylation. J Biol Chem. 2014 Sep 23. pii: jbc.M114.597153. PMID:25248746 doi:https://dx.doi.org/10.1074/jbc.M114.597153
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