Cloning, expression and biochemical characterization of recombinant superoxide dismutase from Antarctic psychrophilic bacterium Pseudoalteromonas sp. ANT506

Abstract

In this study, a superoxide dismutase gene (PsSOD) from Pseudoalteromonas sp. ANT506 was cloned and over expressed in Escherichia coli. The PsSOD has an open reading frame of 582 bp with a putative product of 193 amino acid residue and an estimated molecular size of 21.4 kDa. His-tagged PsSOD was subsequently purified 12.6-fold by Ni-affinity chromatography and the yield of 22.9%. The characterization of the purified rPsSOD exhibited maximum activity at 30 °C and pH 8.0. The enzyme exhibited 13.9% activity at 0 °C and had high-thermo lability at higher than 50 °C. rPsSOD exhibited well capability to 2.5 M NaCl (62.4%). These results indicated that rPsSOD exhibited special catalytic properties.

Cloning and characterization of iron‐superoxide dismutase in Antarctic yeast strain Rhodotorula mucilaginosa AN5

“…), which suggested that RmFeSOD was a dimeric protein composed of two 23.5 kDa subunits. The dimeric organization of RmFeSOD, being similar to most of typical Fe‐SODs , could increase enzymatic flexibility to adapt the extreme conditions .…”

“…According to reports, Pseudoalteromonas sp. ANT506 Fe‐SOD had conservative WEHAYY sequence and conservative amino acid binding site of iron: His 18 , His 74 , His 167 , and Asp 162 . Sonneratia alba Fe‐SOD had conserved amino acids of WEHAYY and conserved Fe‐binding sites: His 27 , His 80 , Asp 164 , and His 168 .…”

“…RmFeSOD was successfully expressed in E. coli BL21 as a soluble protein with calculated activity of 92.11 U mg −1 , which was higher than plant Fe‐SOD with activity of 2.54 U mg −1 from J. curcas , marine algae Fe‐SOD with activity of 16.9 U mg −1 from Enteromorpha linza , bacterium SOD with activity of 39.97 U mg −1 from Lactobacillus casei Lc18 , and even prominently higher than other psychrophile Fe‐SOD with activity of 46.63 U mg −1 from Antarctic bacterium Pseudoalteromonas sp. ANT506 . The highly active RmFeSOD might act as key role in protecting polar organisms against oxidative stress in Antarctic extreme environments.…”

“…XMH10 RhSOD (more than 70% residual activity at pH 4.0–12.0 for 30 min) , Antarctic psychrophilic bacterium Pseudoalteromonas sp. ANT506 rPsSOD (more than 70% residual activity at pH 6.0–10.0 for 30 min) , and cyanobacterium Spirulina platensis Fe‐SOD (about 60% residual activity at pH 6.0–10.0 for 1 h) , and so on. The high pH stability of RmFeSOD might be due to its preservation of dimer nature status in broad pH range .…”

“…Presently, a number of Fe‐SOD genes has been cloned, such as Jatropha curcas , Aeropyrum pernix , Pseudoalteromonas sp. , Rhodothermus sp. , Enteromorpha linza , P .…”