Title: Global Proteome Response to Deletion of Genes Related to Mercury Methylation and Dissimilatory Metal Reduction Reveals Changes in Respiratory Metabolism in Geobacter sulfurreducens PCA

Abstract

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 themore » 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.« less

Authors:

Qian, Chen ^[1]; Johs, Alexander ^[2]; Chen, Hongmei ^[2]; Mann, Benjamin F. ^[2]; Lu, Xia ^[2]; Abraham, Paul E. ^[3]; Hettich, Robert L. ^[1]; Gu, Baohua ^[2]

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+ Show Author Affiliations

1. 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
2. Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
3. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States

Publication Date:

Fri Sep 02 00:00:00 EDT 2016

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1315838

Alternate Identifier(s):

OSTI ID: 1319186

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Published Article

Journal Name:

Journal of Proteome Research

Additional Journal Information:

Journal Name: Journal of Proteome Research Journal Volume: 15 Journal Issue: 10; Journal ID: ISSN 1535-3893

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

60 APPLIED LIFE SCIENCES; Comparative proteomics; gene deletion; acetyl-CoA pathway; mercury reduction; methylation; metabolic processes; ΔomcBESTZ; ΔhgcAB