Naslov
Evolution of Streptomyces genomes

Autori
Hranueli, Daslav

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, pregledni

Izvornik
Zbornik sažetaka priopćenja,Šestog kongresa biologa Hrvatske / Huber, Đuro - Zagreb : Hrvatsko biološko društvo, 1997, 92-93

Skup
Šesti kongres biologa Hrvatske

Mjesto i datum
Opatija, Hrvatska, 22.09.1997. - 26.09.1997

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
Streptomyces; evolution; genome

Sažetak
Streptomyces are Gram-positive, spore-forming bacteria which grow vegetatively in a mycelial form. Historically, they were classified as fungi, with whom they share a common habitat and overall appearance. Subsequently, they were classified correctly as bacteria - based on their cytology, biochemical composition and genetics. Whereas almost all prokaryotic chromosomes are circular, those of Streptomycetes are linear and almost twice the size (about 8 Mb) of Escherichia coli chromosome. Genetic mapping of several species has revealed two striking features: (a) 2 long arcs of 'silent regions', opposite each other, with no identifiable genetic marker and (b) genes involved in biosynthesis of certain metabolites also diametrically-opposite on the linkage map. These features might have occurred by serendipity, but could also have arisen from the duplication of a smaller progenitor chromosome. Streptomyces could represent a possible link in evolution between unicellular prokaryotes and mycelial lower eukaryotes, so understanding more about the evolution of their genomes is important. S. rimosus, the oxytetracycline (OTC) producer, was characterized genetically and physically. The OTC-cluster was cloned and a restriction map derived. Physical map of the 8 Mb linear chromosome shows that it lies in a 'genetically-silent' region, some 600 kb from one chromosome end, which accounts for its frequent spontaneous amplifications and/or deletions. Class II mutants deleted one chromosomal end including the whole cloned OTC-cluster. However, pseudo-revertants of the Class II mutants that had regained the OTC activity were isolated. Restriction mapping and hybridization studies of their DNA suggest the existence of the second OTC-cluster in the S. rimosus chromosome being the first physical evidence of the hypothesis formulated by David Hopwood some time ago.

Izvorni jezik
Engleski

Znanstvena područja
Prehrambena tehnologija

POVEZANOST RADA