Naslov
Are Streptomycetes a link in evolution between unicellular prokaryotes and mycelial lower eukaryotes?

Autori
Paravić Radičević, Andrea ; Denapaite, Dalia ; Čajavec, Branka ; Hunter, S. Iain ; Hranueli, Daslav ; Cullum, John

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

Izvornik
Book of Abstracts / Jerka Dumić et al. - Zagreb : Farmaceutsko-biokemijski fakultet Sveučilišta u Zagrebu, 2002

Skup
1st Croatian Congress on Molecular Life Sciences

Mjesto i datum
Opatija, Hrvatska, 09.06.2002. - 13.06.2002

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
Streptomycetes; fungi; circular chromosomes; linear chromosomes; stable diploids

Sažetak
Historically, the Streptomycetes were classified as fungi, with which they share a common habitat and superficial appearance. Subsequently, they were classified correctly as bacteria - based on their histology, biochemical composition and genetics. Therefore, it came as a surprise to discover that members of the genus have a single linear chromosome, in contrast to most other bacterial species that have circular chromosomes. They thus share the common feature of linear chromosomes with the eukaryotes, although the exact details of chromosomal architecture may be different. Our experiments with two distantly-related species of Streptomyces showed that sequences from the terminal regions could be retained at low copy number in apparent deletion strains. In the case of S. lividans, it was shown that there was a free chromosome end present in the low copy number sequences. In S. rimosus the Class II mutants showed apparent loss of one chromosome end. The new junction bands for AseI and XbaI were weak in comparison to neighbouring bands. An explanation for this would be if two copies of the chromosome had fused in inverted orientation, as this would produce junction fragments of the observed sizes. The junction bands would be weak, because they are only present in one copy, whereas all other bands would be double bands and they would be distant from the two-replication origins. Circularisation of the chromosome in S. lividans and recombination in S. rimosus of two chromosomes to form a single fusion chromosome with large segments in inverted orientation would each produce a second smaller recombination product carrying both chromosome ends, but no known replication origin. As S. lividans and S. rimosus are among the most distantly related strains in the genus Streptomyces, it seems likely that these phenomena are general. The existence of a relatively stable diploid structure would make Streptomycetes a possible link in evolution between unicellular prokaryotes (Eubacteria) and mycelial lower eukaryotes, so understanding more about the biology of their genomes is important.

Izvorni jezik
Engleski

Znanstvena područja
Biotehnologija

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