A Shift Between Mineral and Nonmineral Sources of Iron and Sulfur Causes Proteome-wide Changes in Methanosarcina barkeri

ABSTRACT: Iron (Fe) and sulfur (S) are required elements for life, and changes in their availability can limit the ecological distribution and function of microorganisms. In anoxic environments, soluble Fe typically exists as ferrous iron (Fe(II)) and S as sulfide (HS-). These species exhibit a strong affinity towards one another, resulting in the formation of sedimentary pyrite (FeS2). Recent, paradigm shifting studies indicate that Fe and S in pyrite can be made bioavailable by methanogens through a reductive dissolution process. However, the impact of the utilization of FeS2, as opposed to canonical Fe and S sources, on the phenotype of cells is not fully understood. Here, shotgun proteomics was utilized to measure changes in the phenotype of Methanosarcina barkeri grown with FeS2, Fe(II)/HS-; or Fe(II)/cysteine. Shotgun proteomics tracked 1019 proteins, with 307 observed to change significantly between growth conditions. Functional characterization and pathway analyses revealed these changes to be systemic, and largely tangential to Fe/S metabolism. As a final step, the proteomics data was viewed with respect to previously collected transcriptomics data to deepen the analysis. Presented here is evidence that M. barkeri adopts distinct phenotypes to exploit specific sources of Fe and S in their environment. This is supported by observed protein abundance changes across broad categories of cellular biology. DNA adjacent metabolism, central carbon metabolism / methanogenesis, metal trafficking, quorum sensing and porphyrin biosynthesis pathways are all features in the phenotypic differentiation.

INSTRUMENT(S): Orbitrap Eclipse

ORGANISM(S): Methanosarcina Barkeri (ncbitaxon:2208)

SUBMITTER: Brian Bothner  

PROVIDER: MSV000092027 | MassIVE | Wed May 24 09:41:00 BST 2023

SECONDARY ACCESSION(S): PXD042477

REPOSITORIES: MassIVE