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The pH dependence of polymerization and bundling by the essential bacterial cytoskeltal protein FtsZ

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Pacheco-Gómez, Raúl, Roper, David I., Dafforn, Tim and Rodger, Alison. (2011) The pH dependence of polymerization and bundling by the essential bacterial cytoskeltal protein FtsZ. PLoS One, Vol.6 (No.6). e19369. ISSN 1932-6203

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Official URL: http://dx.doi.org/10.1371/journal.pone.0019369

Abstract

There is a growing body of evidence that bacterial cell division is an intricate coordinated process of comparable complexity to that seen in eukaryotic cells. The dynamic assembly of Escherichia coli FtsZ in the presence of GTP is fundamental to its activity. FtsZ polymerization is a very attractive target for novel antibiotics given its fundamental and universal function. In this study our aim was to understand further the GTP-dependent FtsZ polymerization mechanism and our main focus is on the pH dependence of its behaviour. A key feature of this work is the use of linear dichroism (LD) to follow the polymerization of FtsZ monomers into polymeric structures. LD is the differential absorption of light polarized parallel and perpendicular to an orientation direction (in this case that provided by shear flow). It thus readily distinguishes between FtsZ polymers and monomers. It also distinguishes FtsZ polymers and less well-defined aggregates, which light scattering methodologies do not. The polymerization of FtsZ over a range of pHs was studied by right-angled light scattering to probe mass of FtsZ structures, LD to probe real-time formation of linear polymeric fibres, a specially developed phosphate release assay to relate guanosine triphosphate (GTP) hydrolysis to polymer formation, and electron microscopy (EM) imaging of reaction products as a function of time and pH. We have found that lowering the pH from neutral to 6.5 does not change the nature of the FtsZ polymers in solution-it simply facilitates the polymerization so the fibres present are longer and more abundant. Conversely, lowering the pH to 6.0 has much the same effect as introducing divalent cations or the FtsZ-associated protein YgfE (a putative ZapA orthologue in E. coli)-it stablizes associations of protofilaments.

Item Type:	Journal Article
Subjects:	Q Science > QR Microbiology
Divisions:	Faculty of Science > Chemistry Faculty of Science > Life Sciences (2010- ) Faculty of Science > Molecular Organisation and Assembly in Cells (MOAC)
Library of Congress Subject Headings (LCSH):	Polymerization, Escherichia coli -- Physiology, Cell division
Journal or Publication Title:	PLoS One
Publisher:	Public Library of Science
ISSN:	1932-6203
Date:	28 June 2011
Volume:	Vol.6
Number:	No.6
Page Range:	e19369
Identification Number:	10.1371/journal.pone.0019369
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC)
Grant number:	GR/S47113/01 (EPSRC), GR/T09224/01 (EPSRC)
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URI:	http://wrap.warwick.ac.uk/id/eprint/38804