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Effects upon metabolic pathways and energy production by Sb(III) and As(III)/Sb(III)-oxidase gene aioA in Agrobacterium tumefaciens GW4

Jingxin Li, Birong Yang, Manman Shi, Kai Yuan, Wei Guo, Mingshun Li, Gejiao Wang*

Agrobacterium tumefaciens GW4 is a heterotrophic arsenite [As(III)]/antimonite [Sb(III)]-
oxidizing strain. The As(III) oxidase AioAB is responsible for As(III) oxidation in the periplasm
and it is also involved in Sb(III) oxidation in Agrobacterium tumefaciens 5A. In addition,
Sb(III) oxidase AnoA and cellular H2O2 are also responsible for Sb(III) oxidation in
strain GW4. However, the deletion of aioA increased the Sb(III) oxidation efficiency in
strain GW4. In the present study, we found that the cell mobility to Sb(III), ATP and NADH
contents and heat release were also increased by Sb(III) and more significantly in the aioA
mutant. Proteomics and transcriptional analyses showed that proteins/genes involved in
Sb(III) oxidation and resistance, stress responses, carbon metabolism, cell mobility, phosphonate
and phosphinate metabolism, and amino acid and nucleotide metabolism were
induced by Sb(III) and were more significantly induced in the aioA mutant. The results suggested
that Sb(III) oxidation may produce energy. In addition, without periplasmic AioAB,
more Sb(III) would enter bacterial cells, however, the cytoplasmic AnoA and the oxidative
stress response proteins were significantly up-regulated, which may contribute to the
increased Sb(III) oxidation efficiency. Moreover, the carbon metabolism was also activated
to generate more energy against Sb(III) stress. The generated energy may be used in Sb
transportation, DNA repair, amino acid synthesis, and cell mobility, and may be released in
the form of heat.



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