Rubrerythrin Explained

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]

Notes and 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 . 10.1046/j.1365-2958.2002.02892.x . 11972784 . 22490654 . 0950-382X.
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 . 10.1038/nsb0696-539 . 8646540 . 21142700 . 1545-9993.
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 . 10.3389/fmicb.2016.01822 . 27917155 . 5114695 . 1664-302X. free .
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 . 10.1128/jb.186.23.7888-7895.2004 . 15547260 . 529063 . 0021-9193.
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 . 10.1016/s0021-9258(18)54757-8 . 1657933 . 0021-9258. free .
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 . 10.1007/s00775-011-0795-6 . 21647777 . 8630279 . 0949-8257.