For the first time, comparative proteomics was conducted to delineate the global response of G. sulfurreducens PCA after deletion of genes related to Hg methylation and dissimilatory metal reduction. We identified cellular networks and metabolic pathways that are affected by the loss of these genes.
This is the first study comparing differences in the proteomes of ΔhgcAB, ΔomcBESTZ and wild-type strains of G. sulfurreducens PCAand provides insight into the impact of these gene deletions on key metabolic processes. Our results support the hypothesis that the function of HgcA and HgcB is linked to one carbon (C1) metabolism through the folate branch of the acetyl-CoA pathway by providing methyl groups required for Hg methylation.
In this work, shotgun proteomics was used to compare global proteome profiles between wild-type Geobacter sulfurreducens PCA and two mutant strains: a ΔhgcAB mutant, which is deficient in two genes known to be essential for the biosynthesis of methylmercury toxin, and a ΔomcBESTZ mutant, which is deficient in five outer membrane c-type cytochromes and thus impaired in its ability for dissimilatory metal ion reduction. We were able to delineate the global response of G. sulfurreducens PCA in both mutants and identify cellular networks and metabolic pathways that were affected by the loss of these genes. Deletion of hgcAB increased the relative abundances of proteins implicated in extracellular electron transfer, including most of the c-type cytochromes, PilA-C, and OmpB, whereas deletion of omcBESTZ significantly increased relative abundances of various methyltransferases, suggesting that a loss of dissimilatory reduction capacity results in elevated activity among C1 metabolic pathways. Our results support the hypothesis that the function of HgcA and HgcB is linked to C1 metabolism through the folate branch of the acetyl-CoA pathway by providing methyl groups required for Hg methylation.
Qian, C.; Johs, A.; Chen, H.; Mann, B. F.; Lu, X.; Abraham, P. E.; Hettich, R. L.; Gu, B., Global proteome response to deletion of genes related to mercury methylation and dissimilatory metal reduction reveals changes in respiratory metabolism in Geobacter sulfurreducens PCA. J. Prot. Res. 2016. DOI: 10.1021/acs.jproteome.6b00263.
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