The effect of gamma-ray irradiation on the Mn(ii) speciation in Deinococcus radiodurans and the potential role of Mn(ii)-orthophosphates

Abstract

D. radiodurans accumulates large quantities of Mn(II), which is believed to form low molecular weight complexes with phosphate and metabolites that protect D. radiodurans from radiation damage. The concentration of Mn(II) species in D. radiodurans during the exponential and stationary phase was determined using high-field EPR and biochemical techniques. In the exponential growth phase cells a large fraction of the manganese was in the form of Mn(II)-orthophosphate complexes. By contrast, the intracellular concentration of these compounds in stationary phase cells was less than 16 μM, while that of Mn superoxide dismutase was 320 μM and that of another, yet unidentified, Mn(II) protein was 250 μM. Stationary cells were found to be equally resistant to irradiation as the exponential cells in spite of having significant lower Mn(II)-orthophosphate concentrations. Gamma irradiation induced no changes in the Mn(II) speciation. During stationary growth phase D. radiodurans favours the production of the two Mn-proteins over low molecular weight complexes suggesting that the latter were not essential for radio-resistance at this stage of growth.

Using Genetically Encodable Self‐Assembling GdIII Spin Labels To Make In‐Cell Nanometric Distance Measurements

“…The intensity of the cellular Gd III :LBT‐3Hx‐LBT:Gd III signal increased with increasing Gd III concentration in the medium (Figure B). Gd III uptake depended on the incubation time, taking up to 4 h to reach equilibrium (Figure C), unlike Mn II , which takes only minutes . Gd III concentrations up to 500 μ m in the medium did not affect survival rate, while only slightly diminishing protein overexpression (Figure S2 in the Supporting Information).…”

Regulation of transcriptional pausing through the secondary channel of RNA polymerase

“…Although the data on intracellular distribution of Mn 2+ ions in Dra are controversial (26,(45)(46)(47), several reports suggest that a significant fraction of Mn 2+ ions is bound to proteins (46,48). Accordingly, Mn 2+ ions were shown to activate several stressinduced enzymes in Dra, including DNA polymerases (49,50), Mn 2+ -dependent superoxide dismutase (45,48), and the PprI protease responsible for activation of dozens of stress-related genes through the cleavage of DdrO repressor (51). Our data suggest that RNAP is another likely target for manganesedependent regulation in Dra.…”

A Genome-Wide Search for Ionizing-Radiation-Responsive Elements in Deinococcus radiodurans Reveals a Regulatory Role for the DNA Gyrase Subunit A Gene's 5′ Untranslated Region in the Radiation and Desiccation Response

“…Indeed, some of the uncovered stress responses in this organism (1)(2)(3)(19)(20)(21)(22) are similar to many well-characterized bacterial stress responses that involve gene expression regulation based on repressors/activators directly regulating at the promoter level; an example of this in Escherichia coli is the SOS response (23,24). Additionally, based on the higher concentration of manganese in D. radiodurans, it has been proposed that Mn 2ϩ forms complexes with amino acids and peptides to act as an antioxidant to protect proteins from reactive oxygen species (ROS) (25)(26)(27)(28). While there is compelling evidence that the protection of the proteome via Mn 2ϩ -peptide complexes is a critical component of D. radiodurans survival, there is significant interest in uncovering other contributing stress response mechanisms and global regulatory networks that might be unique to this organism.…”