Proteomic Analysis of Cr (VI) Reducing Synechocystis sp. AHZ-HB-MK and its Mutant Obtained by Gamma Irradiation

Saiqa Razi, Shahida Hasnain, Byung-Gee-Kim

Abstract

ABSTRACT:
A chromium resistant Synechocystis species, AHZ-HB-MK (DQ 381960) was used in this study. It was aimed to characterize this strain at molecular level and
to produce certain mutants with better chromate reduction abilities. The strain was irradiated with a 60Co source in a dose range of 0.5, 1, 2, 5, 10 and 20 Gy at
different stages of growth (after 5, 15 and 30 days) of incubation. The selected derivatives were characterized morphologically, physiologically and biochemically. Chromium reduction activity and the amount of Cr (VI) accumulated within the cells of all of the selected derivatives were estimated. Protein profiling was done to study the impact of gamma rays on the proteins. Protein profiling proved that in the case of cultures irradiated after 5 days of incubation, maximum protection of proteins to radiation damage was observed at 0.5, 1, 2 and 5 Gy. Maximum expression of stress proteins was observed in the derivative obtained at 2 Gy. This derivative was labeled as Synechocystis MKTR. Identification of these proteins was done by mass-spectrometry. Seventy-four peptides were identified from ten selected protein bands. In these peptides sll0170 a heat shock protein, slr2076 a 60kD chaperonin and sll0416 identified as 60kD chaperonin 2 and GroEL2. Whereas sll0170 was also a heat shock protein 70, slr1198 was identified to be an antioxidant protein and slr1516 was annotated as superoxide dismutase which may be involved in the chromate resistance in this strain.