Biophysics

Embedded Sensors

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Science  09 Oct 2009:
Vol. 326, Issue 5950, pp. 207
DOI: 10.1126/science.326_207a
CREDIT: DUPRES ET AL., NAT. CHEM. BIOL. 5, 10.1038/NCHEMBIO.220 (2009)

Drugs used in the treatment of fungal infections are often directed against the protective fungal cell wall (gray). Hence, a better understanding of how cell wall integrity is maintained under dynamic and stressful conditions has pharmaceutical implications. Proteins anchored in the underlying plasma membrane (orange) are thought to detect surface stress and to mediate adaptive responses, but the biophysics of stress sensing is unclear.

Dupres et al. have used atomic force microscopy (AFM) to characterize the response of the yeast plasma membrane protein Wsc1 to mechanical stress. Although the outer end of wild-type Wsc1 (red) is buried within the cell wall, adding a short extension (yellow) containing a histidine tag rendered the fusion protein accessible to a Ni2+-derivatized AFM tip. Scanning the surfaces of live yeast cells and focusing on individual Wsc1 molecules revealed that they exhibited Hookean behavior with a spring constant of roughly 5 pN nm−1. That is, lengthening of Wsc1 was linearly proportional to the force applied. This force-extension behavior required glycosylation (blue), which is expected to favor an extended and relatively stiff protein conformation and may be a key factor in the function of this nanospring.

Nat. Chem. Biol. 5, 10.1038/nchembio.220 (2009).

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