2457-80-9Relevant articles and documents
Chu et al.
, p. 1399,1401,1402,1404 (1968)
Engineered SAM Synthetases for Enzymatic Generation of AdoMet Analogs with Photocaging Groups and Reversible DNA Modification in Cascade Reactions
Michailidou, Freideriki,Kl?cker, Nils,Cornelissen, Nicolas V.,Singh, Rohit K.,Peters, Aileen,Ovcharenko, Anna,Kümmel, Daniel,Rentmeister, Andrea
, p. 480 - 485 (2021)
Methylation and demethylation of DNA, RNA and proteins has emerged as a major regulatory mechanism. Studying the function of these modifications would benefit from tools for their site-specific inhibition and timed removal. S-Adenosyl-L-methionine (AdoMet) analogs in combination with methyltransferases (MTases) have proven useful to map or block and release MTase target sites, however their enzymatic generation has been limited to aliphatic groups at the sulfur atom. We engineered a SAM synthetase from Cryptosporidium hominis (PC-ChMAT) for efficient generation of AdoMet analogs with photocaging groups that are not accepted by any WT MAT reported to date. The crystal structure of PC-ChMAT at 1.87 ? revealed how the photocaged AdoMet analog is accommodated and guided engineering of a thermostable MAT from Methanocaldococcus jannaschii. PC-MATs were compatible with DNA- and RNA-MTases, enabling sequence-specific modification (“writing”) of plasmid DNA and light-triggered removal (“erasing”).
The Catalytic Mechanism of the Class C Radical S-Adenosylmethionine Methyltransferase NosN
Ding, Wei,Li, Yongzhen,Zhao, Junfeng,Ji, Xinjian,Mo, Tianlu,Qianzhu, Haocheng,Tu, Tao,Deng, Zixin,Yu, Yi,Chen, Fener,Zhang, Qi
supporting information, p. 3857 - 3861 (2017/03/27)
S-Adenosylmethionine (SAM) is one of the most common co-substrates in enzyme-catalyzed methylation reactions. Most SAM-dependent reactions proceed through an SN2 mechanism, whereas a subset of them involves radical intermediates for methylating non-nucleophilic substrates. Herein, we report the characterization and mechanistic investigation of NosN, a class C radical SAM methyltransferase involved in the biosynthesis of the thiopeptide antibiotic nosiheptide. We show that, in contrast to all known SAM-dependent methyltransferases, NosN does not produce S-adenosylhomocysteine (SAH) as a co-product. Instead, NosN converts SAM into 5′-methylthioadenosine as a direct methyl donor, employing a radical-based mechanism for methylation and releasing 5′-thioadenosine as a co-product. A series of biochemical and computational studies allowed us to propose a comprehensive mechanism for NosN catalysis, which represents a new paradigm for enzyme-catalyzed methylation reactions.
Organometallic Complex Formed by an Unconventional Radical S-Adenosylmethionine Enzyme
Dong, Min,Horitani, Masaki,Dzikovski, Boris,Pandelia, Maria-Eirini,Krebs, Carsten,Freed, Jack H.,Hoffman, Brian M.,Lin, Hening
supporting information, p. 9755 - 9758 (2016/08/19)
Pyrococcus horikoshii Dph2 (PhDph2) is an unusual radical S-adenosylmethionine (SAM) enzyme involved in the first step of diphthamide biosynthesis. It catalyzes the reaction by cleaving SAM to generate a 3-amino-3-carboxypropyl (ACP) radical. To probe the reaction mechanism, we synthesized a SAM analogue (SAMCA), in which the ACP group of SAM is replaced with a 3-carboxyallyl group. SAMCA is cleaved by PhDph2, yielding a paramagnetic (S = 1/2) species, which is assigned to a complex formed between the reaction product, α-sulfinyl-3-butenoic acid, and the [4Fe-4S] cluster. Electron-nuclear double resonance (ENDOR) measurements with 13C and 2H isotopically labeled SAMCA support a π-complex between the C=C double bond of α-sulfinyl-3-butenoic acid and the unique iron of the [4Fe-4S] cluster. This is the first example of a radical SAM-related [4Fe-4S]+ cluster forming an organometallic complex with an alkene, shedding additional light on the mechanism of PhDph2 and expanding our current notions for the reactivity of [4Fe-4S] clusters in radical SAM enzymes.