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Intermediate filament-like proteins in bacteria and a cytoskeletal function in Streptomyces
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology.
2008 (English)In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 70, no 4, 1037-1050 p.Article in journal (Refereed) Published
Abstract [en]

Actin and tubulin cytoskeletons are conserved and widespread in bacteria. A strikingly intermediate filament (IF)-like cytoskeleton, composed of crescentin, is also present in Caulobacter crescentus and determines its specific cell shape. However, the broader significance of this finding remained obscure, because crescentin appeared to be unique to Caulobacter. Here we demonstrate that IF-like function is probably a more widespread phenomenon in bacteria. First, we show that 21 genomes of 26 phylogenetically diverse species encoded uncharacterized proteins with a central segmented coiled coil rod domain, which we regarded as a key structural feature of IF proteins and crescentin. Experimental studies of three in silico predicted candidates from Mycobacterium and other actinomycetes revealed a common IF-like property to spontaneously assemble into filaments in vitro. Furthermore, the IF-like protein FilP formed cytoskeletal structures in the model actinomycete Streptomyces coelicolor and was needed for normal growth and morphogenesis. Atomic force microscopy of living cells revealed that the FilP cytoskeleton contributed to mechanical fitness of the hyphae, thus closely resembling the function of metazoan IF. Together, the bioinformatic and experimental data suggest that an IF-like protein architecture is a versatile design that is generally present in bacteria and utilized to perform diverse cytoskeletal tasks.

Place, publisher, year, edition, pages
2008. Vol. 70, no 4, 1037-1050 p.
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:uu:diva-107121DOI: 10.1111/j.1365-2958.2008.06473.xISI: 000260194300022OAI: oai:DiVA.org:uu-107121DiVA: diva2:227718
Available from: 2009-07-16 Created: 2009-07-16 Last updated: 2011-11-03Bibliographically approved
In thesis
1. Coiled coil Cytoskeleton in Bacterial Cell Architecture: Studies of Growth and Development in Streptomyces
Open this publication in new window or tab >>Coiled coil Cytoskeleton in Bacterial Cell Architecture: Studies of Growth and Development in Streptomyces
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacterial cytoskeleton is an exciting and relatively new field of research. Recent findings have proven that microbes are well-organized and neatly structured organisms. In this study we have shown that intermediate filament-like proteins with a characteristic rod domain architecture of coiled coil segments separated by non-coiled coil linkers, are widely spread among bacteria.

We identified and characterized an intermediate filament-like protein (named FilP after filamentous protein) in Streptomyces coelicolor. It shares the characteristic biochemical property of eukaryotic intermediate filaments of formation of spontaneous filaments in vitro without requiring any energy or co-factor. We have provided here a preliminary model of its assembly in vitro. FilP also forms in vivo filaments in S. coelicolor hyphae, which are strongest at the sub-apical location of growing vegetative hyphae. We have proposed that FilP cytoskeletal network provides rigidity to the hyphae, especially at the growing tips, by interacting with an essential coiled coil protein DivIVA and possibly other partner elements, yet to be found.

S. coelicolor is a well-studied model organism with a complicated life cycle. It germinates from a spore and spreads by forming branched vegetative hyphae. Lack of nutrients in the environment initiates formation of aerial hyphae in the air, perpendicular to the vegetative ones. The aerial hyphae differentiate into spore chains and eventually grey-pigmented dispersed individual spores are released. The signals involved in sporulation including cell division and chromosome segregation are not clear yet. We characterized here a novel locus consisting of two genes: a small putative membrane protein with no defined function, named SmeA and a member of the SpoIIIE/FtsK family, called SffA. The expression of this locus appears to be dependent on whiA and whiG-whiH-whiI pathways. This finding is intriguing as it can provide insight to the relationship between two apparently unrelated pathways, both leading to the same function of septation and maturation during sporulation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 64 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 849
Keyword
Coiled coil proteins, Bacterial cytoskeleton, Differentiation
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-158271 (URN)978-91-554-8145-2 (ISBN)
Public defence
2011-10-13, B41, Husargatan 3, Bio medical Center (BMC), Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2011-09-22 Created: 2011-09-06 Last updated: 2011-11-03Bibliographically approved

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