Bacteria of the genus Streptomyces are characterized by a complex morphologic differentiation cycle accompanied by the production of numerous extracellular enzymes as well as secondary metabolites. These metabolites have great structural and functional diversity (antibiotics, insecticides, herbicides, antivirals, etc.).

Their genomes are among the largest bacterial genomes (8 Mb). The genomic DNA is linear and has a high G + C content (72%); it contains a large number of original mobile genetic elements, such as integrative elements.

These bacteria present a phenomenon of genetic instability resulting from telomeric instability. Genomic rearrangements define a large region which is non-essential under laboratory conditions. Genes implicated in the synthesis of secondary metabolites (PKS) or the regulation of gene expression have been identified in the terminal regions of the chromosome. Furthermore, analysis of genomic rearrangements and of intra- and interspecific polymorphisms in these regions suggests that exchanges of genetic information are frequent in these areas. On the other hand, the more internal regions of the chromosome are characterized by a higher level of genetic conservation.

The project comprises the sequencing of the terminal regions of the chromosome of S. ambofaciens (2.6 Mb, which is about 25% of the totality of the genome). The objective is to identify the functions coded by these regions and to compare the sequences of S. ambofaciens with those of the related species S. coelicolor A3(2). This analysis will furnish essential elements, with a strong economic impact, for the understanding of the role of gene flux (recombination of new information and rearrangement of existing information) in the evolution of the genome in Streptomyces as well as on the expression of the metabolism.

The Streptomyces web page.