Efficient methylation of C2 in l-tryptophan by the cobalamin-dependent radical S-adenosylmethionine methylase TsrM requires an unmodified N1 amine
作者:Anthony J. Blaszczyk、Bo Wang、Alexey Silakov、Jackson V. Ho、Squire J. Booker
DOI:10.1074/jbc.m117.778548
日期:2017.9
TsrM catalyzes the methylation of C2 in l-tryptophan (Trp). This reaction is the first step in the biosynthesis of the quinaldic acid moiety of the thiopeptide antibiotic thiostrepton, which exhibits potent activity against Gram-positive pathogens. TsrM is a member of the radical S-adenosylmethionine (SAM) superfamily of enzymes, but it does not catalyze the formation of 5'-deoxyadenosin-5'-yl or any
TsrM催化L-色氨酸(Trp)中C2的甲基化。该反应是硫肽抗生素硫链丝菌肽的喹啉酸部分生物合成的第一步,其对革兰氏阳性病原体表现出有效的活性。TsrM是酶的S-腺苷甲硫氨酸(SAM)自由基超家族的成员,但它不催化5'-脱氧腺苷5'-yl或任何其他SAM衍生的自由基的形成。除[4Fe-4S]簇外,TsrM还包含钴胺素辅因子,该辅因子在其反应中充当中间甲基载体。然而,该辅因子如何将甲基部分提供给Trp底物尚不清楚。在这里,我们表明未修饰的Trp N1位置对于营业额很重要,并且1-thia-Trp和1-oxa-Trp充当竞争性抑制剂。我们还表明,在不存在环丙基开环的情况下,β-环丙基-Trp经历C2甲基化,不利于涉及吲哚环C3上不成对电子密度的机制。此外,我们表明,Trp的所有其他吲哚取代的类似物均以不同但可测量的速率进行甲基化,并且预期会减弱Trp中C2的亲核性的类似物7-氮杂-Trp是非常