Phan Chin-Soon, Morinaka Brandon I
Department of Pharmacy, National University of Singapore Singapore 117544 Singapore
Latvian Institute of Organic Synthesis Aizkraukles Street 21 LV-1006 Riga Latvia.
RSC Chem Biol. 2024 Oct 23;5(12):1195-200. doi: 10.1039/d4cb00227j.
Radical SAM cyclophane synthases catalyze C-C, C-N, and C-O crosslinking reactions in the biosynthesis of bioactive peptide natural products. Here, we studied an uncharacterized rSAM enzyme, HtkB from sp., and found this enzyme to catalyze the formation of a HisC2-to-LysCβ crosslink. We used a combination of ColabFold and mutagenesis studies to show that residues D214 in HtkB and H204 in HaaB (another cyclophane synthase) are important for substrate specificity. Mutation of these residues changes the specificity and lowers substrate recognition on the wild-type motifs. This result opens opportunities to alter the specificity and promiscuity for rSAM peptide modifying enzymes.
自由基S-腺苷甲硫氨酸环烷合成酶在生物活性肽天然产物的生物合成中催化碳-碳、碳-氮和碳-氧交联反应。在此，我们研究了一种未表征的rSAM酶，来自 种的HtkB，发现该酶催化HisC2到LysCβ交联的形成。我们结合使用ColabFold和诱变研究表明，HtkB中的D214残基和HaaB（另一种环烷合成酶）中的H204残基对底物特异性很重要。这些残基的突变会改变特异性并降低对野生型基序的底物识别。这一结果为改变rSAM肽修饰酶的特异性和混杂性提供了机会。
