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Regulatory pathways in Streptomyces spp. / A closer look at the regulatory cascade started by the A-factor in Streptomyces griseus and the regulatory pathway in Streptomyces fradiae which leads to the production of tylosin

Jong, I.P. de (2010) Regulatory pathways in Streptomyces spp. / A closer look at the regulatory cascade started by the A-factor in Streptomyces griseus and the regulatory pathway in Streptomyces fradiae which leads to the production of tylosin. Bachelor's Thesis, Biology.

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Abstract

Streptomyces species are the largest source of naturally produced antibiotics. Since resistance against the known antibiotics continues to grow there is always a need to find new antibiotics. The genes needed for antibiotic production are located in large gene clusters that take up a large area of the genome. The regulation of these biosynthesis clusters is often a complicated system. The synthesis of tylosin in Streptomyces fradiae for instance is controlled by a regulatory cascade with no less than five regulators. It starts with a γ-butyrolactone binding to its receptor TylP which in turn activates the transcription of three genes; tylP, tylQ and tylS. The interplay of these three genes, plus two more activated by TylS, leads to the activation of the tylosin biosynthesis pathway. The synthesis of streptomycin in Streptomyces griseus has a straightforward regulatory cascade leading to its synthesis. From the systems known today it is relatively rare in the amount of processes it activates ranging from numerous processes in morphological differentiation to many aspects of secondary metabolism. In both systems there is an important role for γ-butyrolactones, small diffusible molecules. Low concentrations of these molecules are enough to switch on their specific pathways. Another important role is for a rare TTA codon in some of the regulatory genes. Only one tRNA is able to translate this codon to leucine. Without this tRNA the pathways will not function and mutant strains sometimes display a very specific phenotype.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 07:31
Last Modified: 15 Feb 2018 07:31
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/9276

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