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Dynamic force spectroscopy of the Helicobacter pylori BabA-Lewis b binding
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. (Optical Tweezers Center)
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.ORCID-id: 0000-0001-5113-3303
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.ORCID-id: 0000-0002-9031-4331
2009 (Engelska)Ingår i: Biophysical Chemistry, ISSN 0301-4622, E-ISSN 1873-4200, Vol. 143, nr 1-2, s. 102-105Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The binding strength of the Helicobacter pylori adhesin–receptor complex BabA-ABO/Lewis b has been analyzed by means of dynamic force pectroscopy. High-resolution measurements of rupture forces were performed in situ on single bacterial cells, expressing the high-affinity binding BabA adhesin, by the use of force measuring optical tweezers. The resulting force spectra revealed the mechanical properties of a single BabA–Leb bond. It was found that the bond is dominated by one single energy barrier and that it is a slipbond. The bond length and thermal off-rate were assessed to be 0.86±0.07 nm and 0.015±0.006 s−1, respectively.

Ort, förlag, år, upplaga, sidor
Amsterdam: Elsevier, 2009. Vol. 143, nr 1-2, s. 102-105
Nyckelord [en]
Optical tweezers, Single bond dissociation, Receptor–ligand interaction, Bond strength, Lewis b receptor
Nationell ämneskategori
Fysik Biokemi och molekylärbiologi
Forskningsämne
fysik
Identifikatorer
URN: urn:nbn:se:umu:diva-21486DOI: 10.1016/j.bpc.2009.03.007ISI: 000267006000012Scopus ID: 2-s2.0-67349196760OAI: oai:DiVA.org:umu-21486DiVA, id: diva2:211326
Tillgänglig från: 2009-04-14 Skapad: 2009-04-14 Senast uppdaterad: 2024-07-02Bibliografiskt granskad
Ingår i avhandling
1. A study of bacterial adhesion on a single-cell level by means of force measuring optical tweezers and simulations
Öppna denna publikation i ny flik eller fönster >>A study of bacterial adhesion on a single-cell level by means of force measuring optical tweezers and simulations
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The intriguing world of microbiology is nowadays accessible for detailed exploration at a single–molecular level. Optical tweezers are a novel instrument that allows for non–invasive manipulation of single cells by the sole use of laser light and operates on the nano– and micrometer scale which corresponds to the same length scale as living cells. Moreover, forces within the field of microbiology are typically in the picoNewton range which is in accordance with the capability of force measuring optical tweezers systems. Both these conformabilities imply that force measuring optical tweezers is suitable for studies of single living cells. This thesis focuses on the mechanisms of bacterial attachments to host cells which constitute the first step in bacterial infection processes. Bacteria bind specifically to host receptors by means of adhesins that are expressed either directly on the bacterial membrane or on micrometer–long adhesion organelles that are called pili. The properties of single adhesin–receptor bonds that mediate adherence of the bacterium Helicobacter pylori are first examined at various acidities. Further on, biomechanical properties of P pili expressed by Escherichia coli are presented to which computer simulations, that capture the complex kinetics of the pili structure and precisely replicate measured data, are applied. Simulations are found to be a powerful tool for investigations of adhesive attributes of binding systems and are utilized in the analyses of the specific binding properties of P pili on a single–pilus level. However, bacterial binding systems generally involve a multitude of adhesin–receptor bonds. To explore bacterial attachments, the knowledge from single–pilus studies is brought into a full multipili attachment scenario which is analyzed by means of theoretical treatments and simulations. The results are remarkable in several aspects. Not only is it found that the intrinsic properties of P pili are composed in an optimal combination to promote strong multipili bindings. The properties of the pili structure itself are also found to be optimized with respect to its in vivo environment. Indeed, the true meaning of the attributes derived at a single–pilus level cannot be unraveled until a multipili–binding system is considered. Whereas detailed studies are presented for the helix–like P pili expressed by Gram–negative Escherichia coli, conceptual studies are presented for the open coil–like T4 pili expressed by Gram–positive Streptococcus pneumoniae. The structural and adhesive properties of these two types of pili differ considerably. These dissimilarities have far–reaching consequences on the adhesion possibilities at both single–pilus and multipili levels which are discussed qualitatively. Moreover, error analyses of conventional data processing methods in dynamic force spectroscopy as well as development of novel analysis methods are presented. These findings provide better understanding of how to perform refined force measurements on single adhesion organelles as well as how to improve the analyses of measurement data to obtain accurate parameter values of biomechanical entities. In conclusion, this thesis comprises a study of bacterial adhesion organelles and the way they cooperate to establish efficient attachment systems that can successfully withstand strong external forces that acts upon bacteria. Such systems can resist, for instance, rinsing effects and thereby allow bacteria to colonize their host. By understanding the complexity, and thereby possible weaknesses, of bacterial attachments, new targets for combating bacterial infections can be identified.

Ort, förlag, år, upplaga, sidor
Umeå: Print & Media, 2009. s. 108
Nationell ämneskategori
Fysik
Forskningsämne
fysik; cellforskning; molekylär cellbiologi
Identifikatorer
urn:nbn:se:umu:diva-21493 (URN)978-91-7264-765-7 (ISBN)
Disputation
2009-05-08, N420, Naturvetarhuset, Umeå Universitet, Umeå, 10:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2009-04-17 Skapad: 2009-04-14 Senast uppdaterad: 2018-06-09Bibliografiskt granskad

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Björnham, OscarBugaytsova, JeannaBorén, ThomasSchedin, Staffan

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Biophysical Chemistry
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