FINDING NOVEL ARSENIC-CONTAINING ANTIBIOTICS

Author

• Minh Bao PhungFollow

Semester of Graduation

Spring 2026

Degree Type

Dissertation/Thesis

Degree Name

MASTER OF SCIENCE IN INTEGRATIVE BIOLOGY

Department

DEPARTMENT OF MOLECULAR AND CELLULAR BIOLOGY

Committee Chair/First Advisor

MASAFUMI YOSHINAGA

Second Advisor

ERIC ALBRECHT

Third Advisor

MOHAMMAD HALIM

Abstract

Some bacteria metabolize arsenic into antibiotics. Arsinothricin (AST), a recently discovered novel broad-spectrum organoarsenical antibiotic, can be biosynthesized via two steps catalyzed by ArsL and ArsM. The goal of this project is to find further promising antibiotics similar to AST. Through genome-mining using arsL as the molecular probe, bacteria have been discovered to have arsL-containing biosynthetic gene clusters, namely Anoxybacillus calidus, which contain two novel genes, ars1 and ars2, which annotated to encode 4-carboxymuconolactone decarboxylase, and biotin carboxylase, respectively.  Given that ArsL converts arsenite to AST-OH, the non-methylated hydroxy AST precursor, it is reasonable to predict that Ars1 decarboxylates AST-OH while Ars2 carboxylates the amine group of the decarboxylated intermediate, leading to the production of an arsenic mimetic of the phosphonate antibiotic fosmidomycin. Thus, the predicted organoarsenical is named arsmidmycin (ASM). The first aim of the project was the purification, identification, and characterization of ASM. The second aim was the preliminary investigation of ASM biosynthetic pathway by using the heterologous expression system. We found that 1) A. calidus converts arsenite into multiple arsenicals, 2) crudely purified major product mass matches the predicted ASM mass, 3) the crudely purified major product exhibits moderate antibiotic activity, 4) methanol extraction is useful to separate ASM from the major pathway intermediate AST-OH, and 5) Escherichia coli construct properly co-express the cloned three ASM biosynthetic genes under optimal culture condition. Altogether, the project made a steady progress and provided insights required to identify and characterize the hypothesized novel natural product ASM and its biosynthetic pathway.