Peter, Emanuel and Dick, Bernhard and Baeurle, Stephan A. (2012) Signaling pathway of a photoactivable Rac1-GTPase in the early stages. PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS, 80 (5). pp. 1350-1362. ISSN 0887-3585, 1097-0134
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In modern life- and medical-sciences major efforts are currently concentrated on creating artificial photoenzymes, consisting of light- oxygen-voltage-sensitive (LOV) domains fused to a target enzyme. Such protein constructs possess great potential for controlling the cell metabolism as well as gene function upon light stimulus. This has recently been impressively demonstrated by designing a novel artificial fusion protein, connecting the AsLOV2-Ja-photosensor from Avena sativa with the Rac1-GTPase (AsLOV2-Ja-Rac1), and by using it, to control the motility of cancer cells from the HeLa-line. Although tremendous progress has been achieved on the generation of such protein constructs, a detailed understanding of their signaling pathway after photoexcitation is still in its infancy. Here, we show through computer simulations of the AsLOV2-Ja-Rac1-photoenzyme that the early processes after formation of the Cys450-FMN-adduct involve the breakage of a H-bond between the carbonyl oxygen FMN-C4=O and the amino group of Gln513, followed by a rotational reorientation of its sidechain. This initial event is followed by successive events including beta-sheet tightening and transmission of torsional stress along the I beta-sheet, which leads to the disruption of the Ja-helix from the N-terminal end. Finally, this process triggers the detachment of the AsLOV2-Ja-photosensor from the Rac1-GTPase, ultimately enabling the activation of Rac1 via binding of the effector protein PAK1. Proteins 2012; (c) 2012 Wiley Periodicals, Inc.
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