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Studies of the mechanism of phosphorylation and regulation of FilP – a protein forming an intermediate filament-like cytoskeleton in Streptomyces

Saba, Karim (2015) MOBT01 20142
Degree Projects in Molecular Biology
Popular Abstract
Unravelling the Bacterial Cytoskeleton

Recent discoveries of several bacterial proteins have led to a general acceptance of the existence of a bacterial cytoskeleton. This cytoskeleton, much like that of eukaryotic cells, is vital for the functionality and wellbeing of Streptomyces, a genus of soil-dwelling bacteria. One such important function is polar growth. This type of growth is directed to only one of the cellular poles rather than occurring at both poles or at the lateral walls like in other bacterial species. This mode of growth leads to the characteristic hyphal (fungal-like) morphology Streptomyces have.

A complex of proteins is involved in controlling this polar growth. The main “leader” is the protein DivIVA. This protein... (More)
Unravelling the Bacterial Cytoskeleton

Recent discoveries of several bacterial proteins have led to a general acceptance of the existence of a bacterial cytoskeleton. This cytoskeleton, much like that of eukaryotic cells, is vital for the functionality and wellbeing of Streptomyces, a genus of soil-dwelling bacteria. One such important function is polar growth. This type of growth is directed to only one of the cellular poles rather than occurring at both poles or at the lateral walls like in other bacterial species. This mode of growth leads to the characteristic hyphal (fungal-like) morphology Streptomyces have.

A complex of proteins is involved in controlling this polar growth. The main “leader” is the protein DivIVA. This protein forms foci, or aggregates, at the growing tips of hyphae and is thought to function in recruiting other proteins needed for growth. During growth, the tip regions become weaker and need something to support them from within the inside. This is where the protein FilP, the focus of this study, comes in.

FilP is not exactly a part of this complex, but it does interact with it and forms filaments right behind it. These filaments appear as gradients that get weaker the farther away from the tip they get. Previous evidence has pointed to FilP providing mechanical support and rigidity to these growing tips. However, not much was known about how FilP is regulated within the cells. That is to say, what keeps the protein active, and what happens when its activity is no longer needed?

The purpose of this study is to investigate how FilP is regulated in the hyphae of Streptomyces coelicolor. Phosphorylation (a type of protein modification) is a wide spread mechanism that organisms from all domains of life employ to control protein activity. Therefore, studies into whether or not FilP is phosphorylated were performed with the help of multiple in-gel phosphorylation detection techniques. Additionally, previous evidence pointed to FilP being degraded with time, so temporal stability studies of FilP were carried out as well.

As it turned out, FilP is actually phosphorylated. Next, it was determined that a mutant form of FilP (that cannot be phosphorylated) localises similarly to the wild type (or common) variant of FilP. Interestingly, FilP was also shown to be degraded with time once its production is stopped. The filaments FilP forms are generally non-dynamic, meaning that they are rigid and stable. But these filaments need to be made dynamic and it could be that protein degradation is how Streptomyces achieve that.

Finally, understanding the proteins that constitute the cytoskeleton of Streptomyces, in addition to furthering our understanding of how these marvellous bacteria function and grow, will help in the understanding of how similar proteins in our cells work. This will eventually lead to a better understanding of our own cells and potential treatments to diseases that involve disrupted functions of these proteins.

Supervisor: Nora Ausmees
Master Degree Project in Microbiology, 60 credits, August 2014-June2015
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Saba, Karim
supervisor
organization
course
MOBT01 20142
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
7756504
date added to LUP
2015-08-07 12:23:00
date last changed
2015-08-07 12:23:00
@misc{7756504,
  author       = {Saba, Karim},
  language     = {eng},
  note         = {Student Paper},
  title        = {Studies of the mechanism of phosphorylation and regulation of FilP – a protein forming an intermediate filament-like cytoskeleton in Streptomyces},
  year         = {2015},
}