Selective Methylation by an ArsM S-Adenosylmethionine Methyltransferase from Burkholderia gladioli GSRB05 Enhances Antibiotic Production,Environmental Science & Technology

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Selective Methylation by an ArsM S-Adenosylmethionine Methyltransferase from Burkholderia gladioli GSRB05 Enhances Antibiotic Production
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-09-16 , DOI: 10.1021/acs.est.2c04324
Jian Chen ₁ , Adriana E Galván ₁ , Thiruselvam Viswanathan ₁ , Masafumi Yoshinaga ₁ , Barry P Rosen ₁

Affiliation

Arsenic methylation contributes to the formation and diversity of environmental organoarsenicals, an important process in the arsenic biogeochemical cycle. The arsM gene encoding an arsenite (As(III)) S-adenosylmethionine (SAM) methyltransferase is widely distributed in members of every kingdom. A number of ArsM enzymes have been shown to have different patterns of methylation. When incubated with inorganic As(III), Burkholderia gladioli GSRB05 has been shown to synthesize the organoarsenical antibiotic arsinothricin (AST) but does not produce either methylarsenate (MAs(V)) or dimethylarsenate (DMAs(V)). Here, we show that cells of B. gladioli GSRB05 synthesize DMAs(V) when cultured with either MAs(III) or MAs(V). Heterologous expression of the BgarsM gene in Escherichia coli conferred resistance to MAs(III) but not As(III). The cells methylate MAs(III) and the AST precursor, reduced trivalent hydroxyarsinothricin (R-AST-OH) but do not methylate inorganic As(III). Similar results were obtained with purified BgArsM. Compared with ArsM orthologs, BgArsM has an additional 37 amino acid residues in a linker region between domains. Deletion of the additional 37 residues restored As(III) methylation activity. Cells of E. coli co-expressing the BgarsL gene encoding the noncanonical radical SAM enzyme that catalyzes the synthesis of R-AST-OH together with the BgarsM gene produce much more of the antibiotic AST compared with E. coli cells co-expressing BgarsL together with the CrarsM gene from Chlamydomonas reinhardtii, which lacks the sequence for additional 37 residues. We propose that the presence of the insertion reduces the fitness of B. gladioli because it cannot detoxify inorganic arsenic but concomitantly confers an evolutionary advantage by increasing the ability to produce AST.

中文翻译：

剑兰 GSRB05 的 ArsM S-腺苷甲硫氨酸甲基转移酶选择性甲基化增强抗生素生产

砷甲基化有助于环境有机砷的形成和多样性，这是砷生物地球化学循环中的一个重要过程。编码亚砷酸盐 (As(III)) S-腺苷甲硫氨酸 (SAM) 甲基转移酶的arsM基因广泛分布于每个王国的成员中。许多 ArsM 酶已被证明具有不同的甲基化模式。当与无机 As(III) 一起孵育时，剑兰伯克霍尔德菌GSRB05 已被证明可合成有机砷抗生素胂菌素 (AST)，但不会产生砷酸甲酯 (MAs(V)) 或砷酸二甲酯 (DMAs(V))。在这里，我们展示了剑兰的细胞当与 MAs(III) 或 MAs(V) 一起培养时，GSRB05 会合成 DMAs(V)。BgarsM基因在大肠杆菌中的异源表达赋予了对 MAs(III) 的抗性，但不赋予对 As(III) 的抗性。细胞甲基化 MAs(III) 和 AST 前体，还原三价羟基胂丝菌素 (R-AST-OH)，但不甲基化无机 As(III)。用纯化的 BgArsM 获得了类似的结果。与 ArsM 直系同源物相比，BgArsM 在结构域之间的接头区域中具有额外的 37 个氨基酸残基。删除额外的 37 个残基恢复了 As(III) 甲基化活性。共表达BgarsL基因的大肠杆菌细胞，该基因编码催化 R-AST-OH 和BgarsM合成的非经典自由基 SAM 酶与共表达BgarsL和来自莱茵衣藻的CrarsM基因的大肠杆菌细胞相比，该基因产生更多的抗生素 AST ，后者缺乏额外 37 个残基的序列。我们建议插入的存在降低了剑兰的适应性，因为它不能解毒无机砷，但同时通过增加产生 AST 的能力赋予进化优势。

更新日期：2022-09-16

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