SINGLE genes that infectious bacteria depend on for their survival have come
to light. The researchers who made the discoveries say their technique could
lead to a new generation of antibiotics.
Resistance to antibiotics is increasing among our microbiological foes.
Existing antibiotics can be tweaked to outwit the bacteria, but they soon
develop resistance to the new line of attack. 鈥淲e need totally new approaches,鈥�
says Hannes Loferer of Genome Pharmaceuticals in Munich.
One alternative is to find genes that are essential for the survival of
bacteria but not humans, and to target these genes with new drugs. Loferer and
his colleagues reasoned that genes that are common to many species of bacteria
would be likely candidates. Biologists have long suspected that genes that are
widely conserved are vital for life.
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To date, the entire genomes of 14 species of bacteria have been sequenced,
including that of Mycoplasma genitalium, one of the simplest bacteria, which has
only about 600 genes. Loferer鈥檚 team compared M. genitalium鈥檚 DNA
sequence with that of Escherichia coli and found that they have 26
genes in common. 鈥淭hese genes were also conserved in all the other sequenced
species,鈥� says Loferer.
To identify which of these genes are essential to E. coli, the
researchers engineered 26 mutant strains that each lacked one of the genes. They
then tested the mutants to see if they could survive. The team say in this
month鈥檚 Nature Biotechnology (vol 16, p 851) that of the 26 genes, six
were found to be essential for survival. Four of these were not essential to
yeast, and may well be nonessential to humans, suggesting that they may be good
targets for future antibiotics.
鈥淭his is the first example of using comparative genomics to look for new
targets for antibiotics,鈥� says Loferer. 鈥淚n the future, specific antibiotic
treatments are going to be of great importance.鈥�