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Genome sequence of Streptococcus pyogenes, the flesh-eating bacterium
  
By Bijal P. Trivedi

Oklahoma scientists have sequenced the genome of the notorious human pathogen, Streptococcus pyogenes. The bacterium is responsible for a wide range of diseases including streptococcal sore throat, scarlet fever, septicemia, toxic shock syndrome, rheumatic fever and necrotizing fasciitis-flesh eating disease.


Electron micrograph of the Streptococcus pyogenes

The single circular chromosome of S. pyogenes, also known as GAS (group A streptococci) contains 1,752 genes. Of these, 83 percent were assigned a role in the cell based on computer programs that predict gene function and comparisons with other genomes. The proteins in GAS were most similar to those seen in B. subtilis, a microbe used to produce industrial enzymes, Lactococcus lactis, a bacterium used in cheese production, and other strains of streptococci.

GAS can survive a broad range of environmental changes in part due to a collection of stress-related genes. These genes produce protective proteins in response to sudden changes in acidity or saltiness.

GAS is a scavenger. Rather than carry genes to synthesize sugars, amino acids and small peptides, the bacterium contains 36 ABC transporter genes that collect and import these nutrients from the environment. The transporter proteins also contribute to multi-drug resistance as they remove toxic chemicals from bacteria.

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Ferretti, J.J. et al. Complete genome sequence of an M1 strain of Streptococcus pyogenes. Proc Natl Acad Sci USA 98, 4658-4663 (April 2001).
 

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