Atomic force sensing of light-induced protein dynamics with microsecond time resolution in bacteriorhodopsin and photosynthetic reaction centers

Itay Rousso, Edward Khatchatryan, Igor Brodsky, Rachel Nachustai, Michael Ottolenghi, Mordechai Sheves, Aaron Lewis

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

This paper reports on experiments that have monitored protein microsecond dynamics with a cantilevered near-field optical glass fiber. In these experiments two photoactive proteins, bacteriorhodopsin (bR) and the photosynthetic reaction center (PS I), are used to demonstrate that such probes can measure light-induced microsecond protein dynamics even though the resonance frequencies of the glass cantilevers used are in the order of a few hundred kilohertz. In the case of the light-driven proton pump, bR, the light-induced atomic force sensing (AFS) signal is negative (indicating contraction) in the microsecond time domain of the L photointermediate and becomes positive (corresponding to expansion) in the subsequent M intermediate that lives for milliseconds. Double pulse experiments from M to bR show that the latter process reverses the AFS signal. Thus, the AFS structural changes are coupled with the (optical) photocycle intermediates. Light-induced contraction and expansion phenomena are also observed in the case of PSI. In both systems the time regime of the dynamic phenomena that have been measured with AFS is five orders of magnitude faster than the fastest previously recorded atomic force detection of dynamic phenomena. This advance portends a new era in dynamic imaging of protein conformational changes.

Original languageEnglish
Pages (from-to)158-164
Number of pages7
JournalJournal of Structural Biology
Volume119
Issue number2
DOIs
StatePublished - 1 Jan 1997
Externally publishedYes

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