U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


Mercury Methylation Genes involved in Additional Microbial Metabolic Pathways
Published: July 27, 2016
Posted: November 10, 2016

The work supports the hypothesis that the function of HgcA and HgcB is linked to one-carbon metabolism of the acetyl-CoA pathway.

The Science
Comparative proteomics of the global response of Geobacter sulfurreducens PCA following the deletion of mercury methylation genes demonstrates that these genes are involved in other cellular metabolic pathways.

The Impact
This study is the first to compare differences in the proteomes of several strains of G. sulfurreducens PCA, demonstrating that the deletion of the genes for mercury methylation leads to impacts on other key metabolic processes in these strains. This work supports 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 mercury methylation.

Summary
In this study, shotgun proteomics was used to compare global proteome profiles between wild-type G. sulfurreducens PCA and two mutant strains in which DhgcAB is deficient in two genes known to be essential for the biosynthesis of methylmercury toxin, and DomcBESTZ is deficient in five outer membrane c-type cytochromes and thus impaired in its ability for dissimilatory metal ion reduction. The team delineated the global response of G. sulfurreducens PCA in both mutants and identified 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. These 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 mercury methylation.

Contact (BER PM)
Paul Bayer
DOE Office of Biological and Environmental Research
Paul.Bayer@science.doe.gov (301-903-5324)

(PI Contact)
Baohua Gu
Oak Ridge National Laboratory
gub1@ornl.gov (865-574-7286)

Funding
This research was funded by the Office of Biological and Environmental Research within the U.S. Department of Energy’s Office of Science, as part of the Mercury Science Focus Area project at Oak Ridge National Laboratory.

Publication
Qian, C., A. Johs, H. Chen, B. F. Mann, X. Lu, P.E. Abraham, R. L. Hettich, and B. Gu. 2016. “Global Proteome Response to Deletion of Genes Related to Mercury Methylation and Dissimilatory Metal Reduction Reveals Changes in Respiratory Metabolism in Geobacter sulfurreducens PCA,” Journal of Proteome Research 15(10), 3340-49. DOI: 10.1021/acs.jproteome.6b00263. (Reference link)

Topic Areas:

  • Research Area: Subsurface Biogeochemical Research
  • Research Area: Genomic Analysis and Systems Biology
  • Research Area: Microbes and Communities

Division: SC-23.1 Climate and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]

Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]

Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]

Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]

Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]

List all highlights (possible long download time)