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Etude du rôle des protéines partenaires de l'actine dans la mécanique des gels branchés de levure

Abstract : In this experimental work we tried to quantify the mechanical properties of yeast branchedactin networks with regard to their biochemical composition. Actin is a semi-flexible biopolymerthat is assembled as part of the cytoskeleton. Proteins partners of actin (ABPs) shape itsfilaments into different type of networks. Arp2/3 is a protein complex that has the propertyto generate branched actin gels. Growing branched actin networks are of particular interest forboth biologists and physicists because of their ability to generate forces necessary to many vitalprocesses such as endocytosis. Here we study in vitro the mechanical properties of such networks,and we focus on the role of one type of actin binding proteins, the crosslinkers. This family ofproteins appears to play a role in both the elastic, viscous and plastic properties of the gels. Weare able to quantify and to compare the impact of three different crosslinkers on branched actinnetworks in yeast.In order to conduct said study, we combined two powerful experimental methods. We used asuperparamagnetic particle-based mechanical measurement technique that was developed in thelab and allows quantitative, high-throughput measurements on very thin gels. And the networkswere reconstituted in vitro by functionalization of the magnetic particles with Las17, which hasbeen showed to activate Arp2/3 for the yeast by our biologist collaborator. We furthermoreworked on both yeast extracts containing all the ABPs of the Arp2/3 networks, and with setsof a few purified proteins, in order to combine a « top-down » (use of mutations in yeast toprevent the expression of protein(s) of interest) and a « bottom-up » (addition of a protein ofinterest in a simplified system) approaches.
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Submitted on : Thursday, November 15, 2018 - 3:33:07 PM
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  • HAL Id : tel-01923936, version 1


Jessica Planade. Etude du rôle des protéines partenaires de l'actine dans la mécanique des gels branchés de levure. Physique [physics]. Université Sorbonne Paris Cité, 2016. Français. ⟨NNT : 2016USPCC285⟩. ⟨tel-01923936⟩



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