Bacterial [Cu,Zn]-superoxide dismutase: phylogenetically distinct from the eukaryotic enzyme, and not so rare after all!

Abstract

Copper-and zinc-containing superoxide dismutases ([Cu,Zn]-SODS) are generally considered almost exclusively eukaryotic enzymes, protecting the cytosol and extracellular compartments of higher organisms from damage by oxygen free-radicals. The recent description of a few examples of bacterial forms of the enzyme, located in the periplasm of different Gram-negative micro-organisms, prompted a re-evaluation of this general perception. A PCRbased approach has been developed and used successfully to identify bacterial genes encoding [Cu,Zn]

Presence of Copper- and Zinc-Containing Superoxide Dismutase in Commensal Haemophilus haemolyticus Isolates Can Be Used as a Marker To Discriminate Them from Nontypeable H. influenzae Isolates

“…In extensive studies, we have established that capsulated or noncapsulated H. influenzae sensu stricto strains do not produce active CuZnSOD (11,12,14,16). The population of capsulated H. influenzae strains falls into two widely separated phylogenetic divisions, and while strains segregating to phylogenetic division II (some serotype a and b strains and serotype f strains) plus serotype e strains (distantly related to phylogenetic division II) possess the sodC gene, they do not produce active enzyme (11,16), probably due to a mutation that converts an active-site histidine to tyrosine (11).…”

“…Bacterial CuZnSODs are enzymes found in the periplasms of various gram-negative bacteria and, in the case of pathogens, are thought to have a role in the protection of organisms against host defense-derived free-radical-mediated damage (1,2,6,11,12,15,27). In extensive studies, we have established that capsulated or noncapsulated H. influenzae sensu stricto strains do not produce active CuZnSOD (11,12,14,16).…”

“…knowing the species designation. Strains used as positive controls were H. haemolyticus NCTC 10839, biotype IV cryptic genospecies H. influenzae strain 16N (16), Neisseria meningitidis MC58 (27), and Actinobacillus pleuropneumoniae 4074 ATCC 27088 (12,13,26); H. influenzae Rd (7, 11) was used as the negative control. A. pleuropneumoniae 4074 and Haemophilus isolates were grown in brain heart infusion (BHI) broth supplemented with 1 g/ml NAD and 10 g/ml hemin at 37°C on an orbital shaker (180 rpm) or on BHI agar plates supplemented with Levinthal's base at 37°C in 5% carbon dioxide (11).…”

Characterization of secA-sod operon in Borrellia burgdorferi.

“…FeSOD is also found in the cytoplasm and protects cytoplasmic enzymes. CuZn-SOD, encoded by sodC, has been localized to the periplasmic space, suggesting that it functions to protect against extracellular O2 - (Kroll et al, 1995).…”

“…Although MnSODs and iron-containing SODs (FeSODs) share sequence homology and are found in prokaryotes, they differ in expression and physiological function (Kirby et al, 1980). The third class of SOD proteins, the copper, zinc-containing SODs (CuZn-SODs), originally thought to be only in eukaryotes, are found in a number of bacteria (Kroll et al, 1995;Benov and Fridovich, 1994;Groote et al, 1997;SanMateo et al, 1998a;Michiels et al, 1994). In E. coli, MnSOD is encoded by sodA and is induced upon exposure to O2 -; whereas FeSOD, encoded by sodB, is expressed constitutively (Kirby et al, 1980;Yost and Fridovich, 1973).…”