ISSN 2736-1756
Advanced Journal of Microbiology Research Vol. 2015
Available online at http://internationalscholarsjournals.org/journal/ajmr
© 2015 International Scholars Journals
Full Length Research Paper
Functional analysis of a putative transcriptional regulator gene dr2539 in Deinococcus radiodurans
Shao Hua, Chang Shenghe*, Li Zongwei, Wang Yanping and Qin Guangyong
Ion Beam Bioengineering Laboratory, Department of Physics, Zhengzhou University, Zhengzhou 450052, China.
Accepted 23 December, 2014
Abstract
The radiation resistant bacterium Deinococcus radiodurans R1 possesses a high intracellular Mn/Fe concentration ratio. Non-enzymic Mn(II) in D. radiodurans acts as an antioxidant to scavenge reactive oxygen species which contributes to its extreme radioresistance. The gene dr2539 encodes a transcriptional regulator that is predicted to be involved in regulating the transportation of Mn(II) or Fe(II) in D. radiodurans R1. In this study, we constructed a dr2539 disruption mutant with D. radiodurans R1 and compared them in growth rates and in intracellular Fe and Mn ions concentrations. We also investigated the phenotypes of the two strains including protease secretion and resistance to heavy metal ions, H2O2 and MV. The results showed that D. radiodurans R1 did not exhibit strong resistance to Hg(II), Ag(I), Cr(VI) and Pb(IV). Disruption of the gene dr2539 in D. radiodurans R1 resulted in an obvious growth defect in Mn-depleted medium and a remarkably-increased sensitivity to Mn(II). The disruption mutant obviously accumulated the intracellular Mn ion and raised the intracellular Mn/Fe ratio in Mn(II)-replete medium, but it had the similar intracellular Mn/Fe ratio with the wild strain in Fe(II)-replete medium. Furthermore, although the mutant accumulated high levels of intracellular Mn/Fe ratio in Mn(II)-replete medium, disruption of the gene dr2539 had no apparent effect on its resistance to H2 O2 and MV. These results suggest that the gene dr2539 in D. radiodurans R1 plays an important role in regulating the transportation of Mn(II) and the correlation between the intracellular Mn/Fe ratio and the antioxidant capacity in D. radiodurans need further study.
Key words Deinococcus radiodurans, intracellular Mn/Fe concentration ratio, reactive oxygen species, minimal inhibitory concentration.