Regulation of developmental transitions in Streptomyces

Título: Regulation of developmental transitions in Streptomyces

Conferenciante: Félix Ramos León. (Dpt. of Molecular Microbiology, John Innes Centre, UK)

Fecha: Martes, 5 de noviembre de 2019. 12:00 h

Lugar: Salón de Grados cicCartuja2

Abstract

My research focuses on understanding the processes controlling the two major transitions in Streptomyces life cycle, the development of aerial hyphae and the cell division events leading to spore formation.

Streptomyces is a genus of soil-dwelling Actinobacteria that under nutrient rich conditions, grow to establish a multicellular vegetative mycelium. However, in response to nutrient depletion, a developmental program is triggered that leads to the formation of reproductive aerial hyphae. Central to this phase of reproductive growth is the formation of a hydrophobic sheath that covers the so-called aerial hyphae. This sheath is composed of two different families of proteins (the chaplins and the rodlins) that collectively enable Streptomyces to break the surface tension and to extend into the air. The chaplins and rodlins are under the control of a sigma factor, BldN, and its cognate anti-sigma factor, RsbN. Degradation of the anti-sigma factor by a process called regulated intramembrane proteolysis is essential to release its repression over BldN.

Following their erection, each multigenomic hypha undergoes a synchronous cell division event that eventually leads to the formation of dozen of unigenomic spores. To initiate sporulation, many regularly-spaced septa are formed in a FtsZ-dependent manner. FtsZ is the bacterial tubulin homolog and plays a main role in bacterial cell division. FtsZ polymerises forming the so-called Z-ring that recruits other cell division components that lead to constriction and cell-cell separation. Proteins involved in Z-ring stability play an important role in this process and defects in normal Z-ring assembly impairs regular septum formation and sporulation.

References

Bibb MJ, Domonkos A, Chandra G & Buttner MJ (2012) Expression of the chaplin and rodlin hydrophobic sheath proteins in Streptomyces venezuelae is controlled by σBldN and a cognate anti-sigma factor, RsbN. Mol Microbiol 84(6) 1033-1049.

Bush MJ, Tschowri N, Schlimpert, Flärdh & Buttner MJ (2015) c-di-GMP signalling and the regulation of developmental transitions in streptomycetes. Nat Rev Microbiol 13: 749-760.

Bush MJ, Bibb MJ, Chandra G, Findlay KC & Buttner MJ (2013) Genes required for aerial growth, cell division, and chromosome segregation are targets of WhiA before sporulation in Streptomyces venezuelae. mBio 4(5) e00684-13.

Schumacher MA, Bush MJ, Bibb MJ, Ramos-León F, Chandra G, Zeng W & Buttner MJ (2018) The crystal structure of the RsbN-σBldN complez from Streptomyces venezuelae defines a new structural class of anti-σ factor. Nucleic Acids Res 46(14): 7405-7417.

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