Rubrerythrin

Crystal structure of Rubrerythrin obtained from Pyrococcus furiosus using methods of X-ray diffraction..

Rubrerythrin (RBR) is a non-heme iron-containing metalloprotein involved in oxidative stress tolerance within anaerobic bacteria. ^[1] It contains a di-iron active site, where peroxide is reduced into two water molecules, and a mono-iron rubredoxin-like domain thought to be involved in electron transfer. ^[2] A majority of known RBR families are utilized as peroxide "scavengers" to defend organisms against oxidative stress.

Function

As a member of the Ferritin-like superfamily, RBRs primary function is iron storage and detoxification. Rubrerythrins utilize their di-iron centers to bind with reactive oxygen species such as Hydrogen Peroxide, further reducing them into water.

RBR reduction is theorized as a particularly important adaptation that occurred in response to the Great Oxygenation event, increasing defensive fitness of all cells exposed to relatively high levels of oxygen and similar byproducts. ^[3]

Although primarily studied within anaerobic bacteria, RBRs have been discovered in multiple different types of cells including: Aerobic, Anaerobic, and Cyanobacteria. ^[4]

Structure

Many formations of RBRs can be identified by four helical structures, chains alpha and beta containing 3 iron atoms. Both N and C-terminals of common RBRs are very similar to Rubredoxin containing amino acid residue sequences. Furthermore, both metalloproteins contain 5 histidine ligands located within the N-terminals of their peptide chains. ^[5]

Mechanism

In a reduced state without exposure to reactive oxygen byproducts, Rubrerythrin contains two water molecules near its di-iron center. During and after exposure to peroxide, Rubrerythrin becomes oxidized, changing rotational conformations beginning around the peroxide binding site. ^[6]

References

1. Sztukowska, Maryta; Bugno, Marcin; Potempa, Jan; Travis, James; Kurtz Jr, Donald M. (2002-04-25). "Role of rubrerythrin in the oxidative stress response of Porphyromonas gingivalis" . Molecular Microbiology. 44 (2): 479–488. doi:10.1046/j.1365-2958.2002.02892.x. ISSN   0950-382X. PMID   11972784. S2CID   22490654.
2. deMaré, Fredrick; Kurtz, Donald M.; Nordlund, Pär (June 1996). "The structure of Desulfovibrio vulgaris rubrerythrin reveals a unique combination of rubredoxin-like FeS4 and ferritin-like diiron domains" . Nature Structural & Molecular Biology. 3 (6): 539–546. doi:10.1038/nsb0696-539. ISSN   1545-9993. PMID   8646540. S2CID   21142700.
3. Cardenas, Juan P.; Quatrini, Raquel; Holmes, David S. (2016-11-18). "Aerobic Lineage of the Oxidative Stress Response Protein Rubrerythrin Emerged in an Ancient Microaerobic, (Hyper)Thermophilic Environment". Frontiers in Microbiology. 7: 1822. doi: 10.3389/fmicb.2016.01822 . ISSN   1664-302X. PMC   5114695 . PMID   27917155.
4. Weinberg, Michael V.; Jenney, Francis E.; Cui, Xiaoyuan; Adams, Michael W. W. (December 2004). "Rubrerythrin from the Hyperthermophilic Archaeon Pyrococcus furiosus Is a Rubredoxin-Dependent, Iron-Containing Peroxidase". Journal of Bacteriology. 186 (23): 7888–7895. doi:10.1128/jb.186.23.7888-7895.2004. ISSN   0021-9193. PMC   529063 . PMID   15547260.
5. Van Beeumen, J.J.; Van Driessche, G.; Liu, M.Y.; LeGall, J. (November 1991). "The primary structure of rubrerythrin, a protein with inorganic pyrophosphatase activity from Desulfovibrio vulgaris. Comparison with hemerythrin and rubredoxin". Journal of Biological Chemistry. 266 (31): 20645–20653. doi: 10.1016/s0021-9258(18)54757-8 . ISSN   0021-9258. PMID   1657933.
6. Dillard, Bret D.; Demick, Jonathan M.; Adams, Michael W. W.; Lanzilotta, William N. (2011-06-07). "A cryo-crystallographic time course for peroxide reduction by rubrerythrin from Pyrococcus furiosus" . Journal of Biological Inorganic Chemistry. 16 (6): 949–959. doi:10.1007/s00775-011-0795-6. ISSN   0949-8257. PMID   21647777. S2CID   8630279.