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Journal of Bacteriology, May 2002, p. 2465-2472, Vol. 184, No. 9
0021-9193/02/$04.00+0 DOI: 10.1128/JB.184.9.2465-2472.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Joshua W. Gatson, Natalie Wreyford, and Mark E. Hart*
Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699
Received 8 October 2001/ Accepted 4 February 2002
Superoxide dismutase (SOD) profiles of clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci (CoNS) were determined by using whole-cell lysates and activity gels. All S. aureus clinical isolates exhibited three closely migrating bands of activity as previously determined for laboratory strains of S. aureus: SodM, SodA, and a hybrid composed of SodM and SodA (M. W. Valderas and M. E. Hart, J. Bacteriol. 183:3399-3407, 2001). In contrast, the CoNS produced only one SOD activity, which migrated similarly to SodA of S. aureus. Southern analysis of eight CoNS species identified only a single sod gene in each case. A full-length sod gene was cloned from Staphylococcus epidermidis and determined to be more similar to sodA than to sodM of S. aureus. Therefore, this gene was designated sodA. The deduced amino acid sequence of the S. epidermidis sodA was 92 and 76% identical to that of the SodA and SodM proteins of S. aureus, respectively. The S. epidermidis sodA gene expressed from a plasmid complemented a sodA mutation in S. aureus, and the protein formed a hybrid with SodM of S. aureus. Both hybrid SOD forms as well as the SodM and SodA proteins of S. aureus and the S. epidermidis SodA protein exist as dimers. These data indicate that sodM is found only in S. aureus and not in the CoNS, suggesting an important divergence in the evolution of this genus and a unique role for SodM in S. aureus.
Present address: Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27858-4354.
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