Deinococcus radiodurans and its interesting habitat

my adopted bacterium is Deinococcus radiodurans it is an extremophilic bacterium and one of the most radiation-resistant organisms known. It can survive cold, dehydration, vacuum, and acid, and therefore is known as a polyextremophile. It has been listed as the world's toughest known bacterium in The Guinness Book Of World Records

The characterization of micrococcus (Deinococcus) radiodurans sark plasmids. This bacterium has been classified as a new genus Deinococcus radiodurans which is resistant to gamma-rays. It can repair itself completely almost all of DNA damages including double strand

D. radiodurans, a second, unique pentameric single-stranded DNA binding protein (encoded by ddrB) has recently been identified as highly up-regulated in response to radiation and is thought to play a major role in the radiation resistance of this organism. In support of this, deletions of this gene are viable, but render the cells moderately radiation sensitive.

In Deinococcus radiodurans, RecBCD holoenzyme is not intact because of the absence of RecB and RecC, but a RecD-like protein does indeed exist. Deinococcus radiodurans cultures were evaluated for their ability to survive exposure to DNA-damaging agents in exponential growth phase. Gamma irradiation was conducted using a 60Co irradiator (Irradiation Center of Zhejiang University, Hangzhou, Zhejiang Province, China). For irradiation with γ rays, the cell suspension diluted to an appropriate concentration was irradiated at room temperature for 1 h with 60Co γ rays at several different dose rates, which were regulated by changing the distance of samples from the γ ray source. For UV irradiation, the cells were plated on respective agar plates at an appropriate concentration, and then exposed to different doses of UV radiation at 254 nm. For analysis of the resistance to hydrogen peroxide, the cultures were treated with different concentrations of hydrogen peroxide for 30 min with vigorous aeration in a 4°C refrigerator. After the treatments, the cells were plated on TGY plates and incubated at 30°C for 3 days before the colonies were enumerated.

Deinococcus radiodurans (DR) is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ) protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.