Bacterial Genomes

Brian Foley btf at t10.lanl.gov
Tue May 12 11:44:39 EST 1998


David J McGee wrote:
> 
> Does anyone know or have thoughts on whether bacterial genomes 
> are in a
> state of expansion (perhaps by horizontal transfer of genes, eg.
> pathogenicity islands), or in a state of reduction (eg, deletion of
> intergenic spaces to form operons).  Over time can we expect bacterial
> genomes to become more compact or acquire more DNA from other sources?

	Some are expanding, others are contracting.  There
is great diversity in the prokaryotic "domains" eubacteria
and archaebacteria, there is not one "force" that acts on all
those different species.
	Many human pathogens have small genomes and have lost 
many genes necessary for free living.  They now import amino
acids and other compounds from the host cells, rather than
making their own from scratch.  One thought is that with fewer 
genes, there are fewer potential immunogenic proteins in the
bacterium so it has a better chance of evading the host immune
system.

-- 
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|Brian T. Foley               btf at t10.lanl.gov                       |
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