Ralph Kirby and Carton W. Chen
from: Streptomyces: Molecular Biology and Biotechnology (Edited by: Paul Dyson). Caister Academic Press, U.K. (2011)
Linear replicons are relatively uncommon among bacteria and their preponderance among the Actinomycetales, and within the Streptomyces in particular, poses some interesting questions. These novel bacterial replicons are capped by terminal proteins that are covalently bound to the 5' ends of the linear DNA and these terminal structures are directly involved in replicating and protecting the ends of the linear genome. In addition and perhaps related to their linear nature, these genomes are among the largest bacterial chromosomes. As far as can be ascertained at present, these large genomes have a specific organizational structure in terms of their genes. The genome structure can be divided into a core region that is present syntenously in most Actinomycetales, two terminal regions that are highly variable throughout the explored Streptomyces and two regions to the left and right of the core region that contain many syntenous genes specific to the Streptomyces and not found in other Actinomycetales. Genome dynamics seems to be important to the Streptomyces with plasmid-chromosome interactions, horizontal gene transfer and interspecific recombination probably playing important roles in how these genomes to adapt to the diverse environment they reside in. Exploring the genome architecture of the Streptomyces helps our understanding of how and why the genus Streptomyces has a unique place in the evolution of the bacteria read more ...