loading page

Structural Evolution of the Ancient Enzyme, Dissimilatory Sulfite Reductase
  • +4
  • Daniel R. Colman,
  • Gilles Labesse,
  • Swapna Gurla,
  • Johanna Stefanakis,
  • Gaetano Montelione,
  • Eric S. Boyd,
  • Catherine Royer
Daniel R. Colman
Montana State University Department of Microbiology and Cell Biology

Corresponding Author:[email protected]

Author Profile
Gilles Labesse
Centre de Biochimie Structurale
Author Profile
Swapna Gurla
Rutgers Robert Wood Johnson Medical School Department of Biochemistry and Molecular Biology
Author Profile
Johanna Stefanakis
Bronx High School of Science
Author Profile
Gaetano Montelione
Rensselaer Polytechnic Institute Department of Chemistry and Chemical Biology
Author Profile
Eric S. Boyd
Montana State University Department of Microbiology and Cell Biology
Author Profile
Catherine Royer
Department of Biological Sciences Rensselaer Polytechnic Institute Troy NY 12180
Author Profile


Dissimilatory sulfite reductase is an ancient enzyme that has linked the global sulfur and carbon biogeochemical cycles since at least 3.47 Gya. While much has been learned about the phylogenetic distribution and diversity of DsrAB across environmental gradients, far less is known about the structural changes that occurred to maintain DsrAB function as the enzyme accompanied diversification of sulfate/sulfite reducing organisms (SRO) into new environments. Analyses of available crystal structures of DsrAB from Archaeoglobus fulgidus and Desulfovibrio vulgaris, representing early and late evolving lineages, respectively, show that certain features of DsrAB are structurally conserved, including active siro-heme binding motifs. Whether such structural features are conserved among DsrAB recovered from varied environments, including hot spring environments that host representatives of the earliest evolving SRO lineage (e.g., MV2-Eury), is not known. To begin to overcome these gaps in our understanding of the evolution of DsrAB, structural models from MV2.Eury were generated and evolutionary sequence co-variance analyses were conducted on a curated DsrAB database. Phylogenetically diverse DsrAB harbor many conserved functional residues including those that ligate active siro-heme(s). However, evolutionary co-variance analysis of monomeric DsrAB subunits revealed several False Positive Evolutionary Couplings (FPEC) that correspond to residues that have co-evolved despite being too spatially distant in the monomeric structure to allow for direct contact. One set of FPECs corresponds to residues that form a structural path between the two active siro-heme moieties across the interface between heterodimers, suggesting the potential for allostery or electron transfer within the enzyme complex. Other FPECs correspond to structural loops and gaps that may have been selected to stabilize enzyme function in different environments. These structural bioinformatics results suggest that DsrAB has maintained allosteric communication pathways between subunits as SRO diversified into new environments. The observations outlined here provide a framework for future biochemical and structural analyses of DsrAB to examine potential allosteric control of this enzyme.
25 Jan 2022Submitted to PROTEINS: Structure, Function, and Bioinformatics
28 Jan 2022Assigned to Editor
28 Jan 2022Submission Checks Completed
29 Jan 2022Review(s) Completed, Editorial Evaluation Pending
29 Jan 2022Editorial Decision: Accept
Jun 2022Published in Proteins: Structure, Function, and Bioinformatics volume 90 issue 6 on pages 1331-1345. 10.1002/prot.26315