The Hindu : Anthrax bacterium genome sequenced

Online edition of India's National Newspaper
Thursday, May 01, 2003

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Anthrax bacterium genome sequenced

By N. Gopal Raj

THIRUVANANTHAPURAM April 30. The lethality of the anthrax bacterium may not be solely the result of genes on its two plasmids (circular bits of DNA), according to the research group which has sequenced its entire genome and whose work will be published in the coming issue of the journal, Nature.

Scientists at the Institute for Genomic Research (TIGR) in the United States have deciphered the entire genome of the ames strain of the anthrax bacterium.

This was the strain used in the U.S. bioweapons programme and in the bioterrorist attacks which affected that country in 2001.

The ames strain sequenced by TIGR was, however, derived from a dead cow in 1981.

The anthrax bacterium's two plasmids carry many of the genes responsible for the organism's virulence and toxicity. In addition, its single chromosome has virulence-enhancing genes with counterparts in its close relative, the common soil bacterium, bacillus cereus. These genes may therefore be part of the common arsenal of the B. cereus group of bacteria. Some of the major differences between the anthrax bacterium and B. cereus may be the result of how these genes are regulated, say the TIGR scientists.

TIGR scientist, Scott Peterson, who led the comparative studies of genes in the anthrax bacterium and its close relatives in the B. cereus group, says that his analysis indicated ``lateral transfer'' of genes between cereus members.

The anthrax bacterium is a soil bacterium gone bad, according to Timothy Read, the first author of the TIGR paper.

``The B. anthracis chromosome sequence portrays a soil-dwelling organism, possessing numerous potential virulence genes, which has possibly a preference for protein-rich environment,'' states the paper.

But an American-French research group, which have sequenced the B. cereus genome and whose paper too is published in the same issue of Nature, thinks otherwise. Comparison of the genomes of the two bacteria ``contradicts the hypothesis of the cereus group's common ancestor being a soil bacterium''. They think that the evidence suggests that the common ancestor lived in the intestine of insects.

The TIGR paper does, however, admit that the presence of certain genes ``may be evidence of an insect-infecting lifestyle in a recent ancestor''.

TIGR's president, Claire Fraser, who supervised the anthrax genome project, says that the genome sequence would be invaluable to researchers developing new drugs or vaccines.

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