Structural insights into actin filament recognition by commonly used cellular actin markers.

Archana Kumari, Shubham Kesarwani, Manjunath G Javoor, Kutti R Vinothkumar, Minhajuddin Sirajuddin

The EMBO journal 2020 Jul 15

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Cellular studies of filamentous actin (F-actin) processes commonly utilize fluorescent versions of toxins, peptides, and proteins that bind actin. While the choice of these markers has been largely based on availability and ease, there is a severe dearth of structural data for an informed judgment in employing suitable F-actin markers for a particular requirement. Here, we describe the electron cryomicroscopy structures of phalloidin, lifeAct, and utrophin bound to F-actin, providing a comprehensive high-resolution structural comparison of widely used actin markers and their influence towards F-actin. Our results show that phalloidin binding does not induce specific conformational change and lifeAct specifically recognizes closed D-loop conformation, i.e., ADP-Pi or ADP states of F-actin. The structural models aided designing of minimal utrophin and a shorter lifeAct, which can be utilized as F-actin marker. Together, our study provides a structural perspective, where the binding sites of utrophin and lifeAct overlap with majority of actin-binding proteins and thus offering an invaluable resource for researchers in choosing appropriate actin markers and generating new marker variants. © 2020 The Authors. Published under the terms of the CC BY 4.0 license.

Citation

Archana Kumari, Shubham Kesarwani, Manjunath G Javoor, Kutti R Vinothkumar, Minhajuddin Sirajuddin. Structural insights into actin filament recognition by commonly used cellular actin markers. The EMBO journal. 2020 Jul 15;39(14):e104006