The regulation of development in the antibiotic-producing bacteria Streptomyces (BUTTNER_J17DTP)

Lead Research Organisation: University of East Anglia
Department Name: Graduate Office

Abstract

Streptomycetes are filamentous bacteria that grow by tip extension and branching to form a vegetative mycelium. Nutrient depletion triggers a developmental program that leads to the formation of specialized reproductive structures called aerial hyphae, which ultimately give rise to long chains of spores. This program is genetically and temporally coordinated with the production of numerous commercially important antibiotics (Streptomycetes account for $40 billion of revenue annually in the pharmaceutical industry worldwide). The transition from vegetative growth to the formation of aerial hyphae is controlled by a regulatory switch consisting of a sigma factor, BldN, and its cognate anti-sigma, RsbN, a transmembrane protein. After BldN is expressed, it is held inactive by RsbN, which sequesters it to the membrane, until an unknown signal triggers Regulated Intramembrane Proteolysis (RIP) of RsbN and release of BldN into the cytoplasm. The goals of this project are to identify the signal that triggers release of BldN and to characterize the proteolytic process that inactivates RsbN.

Bibb, M.J., Domonkos, Á., Chandra, G., and Buttner, M.J. (2012) Expression of the chaplin and rodlin hydrophobic sheath proteins in Streptomyces venezuelae is controlled by BldN and a cognate anti-sigma factor, RsbN. Mol. Microbiol. 84:1033-1049.

Bush, M.J., Tschowri, N., Schlimpert, S., Flärdh, K., and Buttner, M.J. (2015) c-di-GMP signalling and the regulation of developmental transitions in streptomycetes. Nature Rev. Microbiol. 13:749-760.

Tschowri, N., Schumacher, M.A., Schlimpert, S., Chinnam, N.B., Findlay, K.C., Brennan, R.G., and Buttner, M.J. (2014) Tetrameric c-di-GMP mediates effective transcription factor dimerization to control Streptomyces development. Cell 158:1136-1147.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M011216/1 01/10/2015 30/09/2023
1911023 Studentship BB/M011216/1 01/10/2017 30/09/2021 Marieta Marinova Avramova
 
Description The classical life cycle of Streptomyces is complex, starting with spore germination and formation of a vegetative mycelium. Upon nutrient depletion, secondary metabolism is initiated and reproductive aerial hyphae extend up into the air. Sporulation septa compartmentalise the multigenomic hyphae, creating unigenomic pre-spore compartments. Mature, pigmented spores then disperse. Two protein families responsible for the major developmental switches in Streptomyces have been identified. Bld regulators are necessary for the erection of aerial hyphae, while Whi regulators are required for the process of sporulation. This work focuses on the elusive BldB, the function of which is currently unknown. BldB has ten paralogues in Streptomyces venezuelae - these paralogues (designated bldB') are often encoded next to paralogues of the DNA-binding regulator whiJ (designated whiJ') and to paralogues of the predicted anti-sigma factor abaA (designated abaA').

We have shown that deletion of bldB in S. venezuelae leads to a classical "bald" phenotype - the mutant is unable to produce aerial hyphae and mature spores. By screening a Bacterial-Two-Hybrid library, we show that BldB strongly interacts with seven of its BldB' paralogues in S. venezuelae. These seven paralogues have conserved amino acid motifs that might be important for interaction with BldB. The deletion of two bldB' paralogues results in developmental phenotypes, leading us to conclude that these paralogues might be necessary for BldB function. To further investigate the role of BldB, we conducted RNA-seq to monitor the expression of genes throughout the life-cycle of the ?bldB mutant. Our data show that the expression of five abaA' paralogues is massively upregulated in the absence of bldB, suggesting that BldB represses the expression of the abaA' paralogues, either directly or indirectly. Taken together, our data suggest that BldB may function via a partner-switching mechanism, involving the paralogues of BldB and potentially also the paralogues of WhiJ and AbaA.
Exploitation Route The outcomes of this award would be most useful in education, as the undertaken research work is mostly of a fundamental nature. However, there is a connection between the developmental biology of Streptomyces, and their striking ability to produce various secondary metabolites, which are widely used in medicine, so it is possible that the results of this PhD will inform future work related to production of novel pharmaceutical products.
Sectors Education,Pharmaceuticals and Medical Biotechnology,Other

 
Description Art and Science Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact 30 students attended an Art and Science Workshop organised by UEA and the Sainsbury Centre for Visual Arts. I was the scientist, and I worked with 2 artists to design a workshop titled "Who is fighting under my feet?" aimed at explaining the bigger picture of my research to students. We had two art activities revolved around the information I presented to the students, visualising concepts, such as antibiotic resistance. The students were very active and engaged well, with a surprising level of scientific knowledge.
Year(s) Of Engagement Activity 2020