Comparative analysis of cyanobacterial superoxide dismutases to discriminate canonical forms

Abstract

Background: Superoxide dismutases (SOD) are ubiquitous metalloenzymes that catalyze the disproportion of superoxide to peroxide and molecular oxygen through alternate oxidation and reduction of their metal ions. In general, SODs are classified into four forms by their catalytic metals namely; FeSOD, MnSOD, Cu/ZnSOD and NiSOD. In addition, a cambialistic form that uses Fe/Mn in its active site also exists. Cyanobacteria, the oxygen evolving photosynthetic prokaryotes, produce reactive oxygen species that can damage cellular components leading to cell death. Thus, the co-evolution of an antioxidant system was necessary for the survival of photosynthetic organisms with SOD as the initial enzyme evolved to alleviate the toxic effect. Cyanobacteria represent the first oxygenic photoautotrophs and their SOD sequences available in the databases lack clear annotation. Hence, the present study focuses on structure and sequence pattern of subsets of cyanobacterial superoxide dismutases.

Essential roles of iron superoxide dismutase in photoautotrophic growth of Synechocystis sp. PCC 6803 and heterogeneous expression of marine Synechococcus sp. CC9311 copper/zinc superoxide dismutase within its sodB knockdown mutant

“…were found in the cyanobacterial Cu/ ZnSOD protein sequence (Priya et al, 2007), and protein sequences (GFHLHAGDQC and GGGGARIACG) of the Cu/ ZnSOD putative encoding gene (sync_1771, sodC) in Synechococcus 9311 (Palenik et al, 2006) fitted well with them. Combined with in-gel activity staining and immunoblotting results, we concluded that sync_1771 in Synechococcus 9311 encoded Cu/ZnSOD (unpublished data).…”

“…All cyanobacteria have a cytosolic sod gene encoding either soluble FeSOD or soluble NiSOD, and these could be the housekeeping SODs (Regelsberger et al, 2004;Priya et al, 2007). Some cyanobacteria have additional SODs, e.g.…”

Fe Sparing and Fe Recycling Contribute to Increased Superoxide Dismutase Capacity in Iron-Starved Chlamydomonas reinhardtii

“…The SODs are a polyphyletic family of metalloproteins, the most common of which contain Fe (FeSODs), Mn (MnSODs), Cu plus Zn (Cu/ZnSODs), or Ni (NiSODs) as active site catalysts. The FeSODs and MnSODs exhibit very similar sequence and structure, reflecting a common ancestry, while the Cu/ ZnSODs and NiSODs are distinct from the FeSODs and MnSODs and from each other (Fink and Scandalios, 2002;Priya et al, 2007). The FeSODs, MnSODs, and Cu/ZnSODs are widely distributed, and organisms typically possess enzymes of more than one class; many cyanobacteria have both FeSODs and MnSODs, metazoa and fungi produce both MnSODs and Cu/ZnSODs, and embryophytes synthesize all three forms (Fink and Scandalios, 2002; reviewed in Grace, 1990;Bowler et al, 1992;Pilon et al, 2011).…”

Iron Containing Superoxide Dismutase of Streptomyces subrutilus P5 Increases Bacterial Heavy Metal Resistance by Sequestration

“…Furthermore, the amino acid sequences (GenBank: AHH25151) verified the presence of the characteristic N-and C-terminal domains (pfam00081 and pfam02777 respectively). The gene also contained the SOD signature, (Priya et al, 2007).…”