| Autor: |
Dilia E. Rangel, Manu Forero-Shelton, Nathaly Marín-Medina |
| Rok vydání: |
2012 |
| Předmět: |
|
| Zdroj: |
Biophysical Journal. 102:150a-151a |
| ISSN: |
0006-3495 |
| Popis: |
Type I pili which mediate bacterial adhesion of E coli, are thought to help bacteria resist drag forces caused by fluid flow. The mechanical properties of these pili have already been studied by AFM force spectroscopy: They were found to elongate significantly at forces above ∼50pN and contract at forces below ∼25pN due to uncoiling and coiling of the quaternary structure of pili. It was speculated that these coiling forces could help bacteria move in opposition to the direction of fluid flow.We show here that pili extend when E coli bacteria are exposed to physiological shear stresses in a flow chamber. Moreover, we observe that pili can indeed help bacteria move against flow. We compare the results obtained in the flow chamber with those obtained by AFM and optical tweezers measurements using the Goldman formula to relate shear stress with force acting on a bacterium. The changes in bacterial position caused by changes in fluid flow are smaller than the changes in length obtained in the AFM experiments, suggesting bacteria bind to the flow chamber surface through more than one pilus.We measure bacterial displacements with sub-micrometric precision by tracking their centers, and conclude that these displacements are consistent with the coiling and uncoiling of pili observed by AFM measurements but not with bacterial or pili deformation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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