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Reference: David Arthur Wilkinson, (2010). Regulation of the expression and positioning of chemotaxis and motor proteins in Rhodobacter sphaeroides. DPhil. University of Oxford.Citable link to this page:

 

Regulation of the expression and positioning of chemotaxis and motor proteins in Rhodobacter sphaeroides

Abstract: Bacteria achieve directed motion through their environments by integrating propulsion withchemical detection in the process of chemotaxis. Central to this process are the macromolecular protein structures of the flagellar motor and the chemoreceptor arrays, which are responsible for motility and chemical sensing, respectively. These protein complexes localise to different discrete subcellular positions in different bacterial species, and their correct subcellular localisation is oftenessential to their function.In the monotrichous α‐proteobacterium Rhodobacter sphaeroides, the flagellum is subpolar and two distinct sets of chemotaxis proteins localise to discrete polar and cytoplasmic positions within thecell.In this study, the development of software for the analysis of fluorescent microscopy images allowed cellular morphologies and the localisation and distribution of the chemoreceptor arrays of R.sphaeroides to be characterised in detail, showing that protein partitioning at cell division resultsin an asymmetric separation of both cytoplasmic and membrane‐bound protein componentsbetween daughter cells.The design of a fluorescence‐based assay for the analysis of gene expression assisted indemonstrating that expression of both the chemotaxis and motor genes of R.sphaeroides isregulated by the sigma factor, FliA, and its inhibitor, FlgM. FliA was then used to achieve varying expression of the chemotaxis genes, and the concentration dependence of array clustering was explored in microscopy images, revealing important differences between cluster formation in R.sphaeroides and other species.,/p>Additionally, FliA was identified as a regulator of flagellar number in R.sphaeroides, controlling a negative feedback‐loop in the hierarchy of flagellar assembly that represses flagellar formation upon secretion of FlgM. The complex regulatory pathway controlling R.sphaeroides flagellar assembly isthe first identified system where completion of a single flagellum directly inhibits the production of a second, a mechanism that may be important to many monotrichous bacterial species.

Digital Origin:Reformatted digital Type of Award:DPhil Level of Award:Doctoral Awarding Institution: University of Oxford

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Prof Judy P ArmitageMore by this contributor

RoleSupervisor

 Bibliographic Details

Issue Date: 2010

Copyright Date: 2010 Identifiers

Urn: uuid:4aa15e05-9608-40af-a33e-21ce578d0dc7 Item Description

Type: thesis;

Language: en Keywords: Rhodobacter sphaeroides FliA FlgM gene expression microscopySubjects: Biochemistry Tiny URL: ora:5319

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Author: Mr David Arthur Wilkinson - institutionUniversity of Oxford facultyMedical Sciences Division - Biochemistry oxfordCollegeMerton C

Source: https://ora.ox.ac.uk/objects/uuid:4aa15e05-9608-40af-a33e-21ce578d0dc7



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