Global Proteome Response to Deletion of Genes Related to Mercury Methylation and Dissimilatory Metal Reduction Reveals Changes in Respiratory Metabolism in Geobacter sulfurreducens PCA
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States, Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
Geobacter sulfurreducens PCA can reduce, sorb, and methylate mercury (Hg); however, the underlying biochemical mechanisms of these processes and interdependent metabolic pathways remain unknown. In this study, shotgun proteomics was used to compare global proteome profiles between wild-type G. sulfurreducens PCA and two mutant strains: a ΔhgcAB mutant, which is deficient in two genes known to be essential for Hg methylation 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, and is consistent with a previously observed increase in Hg reduction in the hgcAB mutant. Deletion of omcBESTZ was found to significantly increase relative abundances of various methyltransferases, suggesting that a loss of dissimilatory reduction capacity results in elevated activity among one-carbon metabolic pathways and thus increased methylation. We show that G. sulfurreducens PCA encodes only the folate branch of the Wood Ljungdahl pathway, and proteins associated with the folate branch were found at lower abundance in the ΔhgcAB mutant strain than the wild type. In conclusion, this observation supports the hypothesis that the function of HgcA and HgcB may be linked to one carbon metabolism through the folate branch of the Wood-Ljungdahl pathway by providing methyl groups required for Hg methylation.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1315838
- Alternate ID(s):
- OSTI ID: 1319186
- Journal Information:
- Journal of Proteome Research, Journal Name: Journal of Proteome Research Vol. 15 Journal Issue: 10; ISSN 1535-3893
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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