AV
Anna Vangone
  • Computational Structural Biology group, Bijvoet Center for Biomolecular Research, Faculty of Science Chemistry, Utrecht University, the Netherlands
Research fields
  • Biochemistry
Probing Conformational States of a Target Protein in Escherichia coli Cells by in vivo Cysteine Cross-linking Coupled with Proteolytic Gel Analysis
Authors:  Sujeet Kumar and Natividad Ruiz , date: 06/20/2019, view: 3929, Q&A: 0
Transporters are dynamic membrane proteins that are essential to the physiology of cells. To function, transporters must cycle between various conformational states, so to understand their mechanistic details, it is critical to characterize how their structure changes during the transport cycle. One approach to studying the dynamics of transporters takes advantage of the chemistry of cysteine by using sulfhydryl-reactive, bi-functional cross-linkers to probe changes in the distance between two specific residues that have been substituted to cysteine. This approach is mostly used to study transporters in vitro, not in their natural cellular environment. Here we describe a protocol based on structure-guided cysteine cross-linking and proteolysis-coupled gel analysis to probe conformational changes of a target transporter in live Escherichia coli cells. Although cross-linking approaches have been used to probe the proximity between transmembrane segments in membrane proteins in vivo, to our knowledge this protocol is the first to be used to interrogate transporter dynamics in cells. The use of this protocol is optimal for proteins with known or modeled structures to guide the replacement of specific residues with cysteines and the selection of cross-linking agents with various spacer arm lengths. This protocol allows for discriminating easily cross-linked and uncross-linked species and does not require the often difficult or unavailable reconstitution of transport activity in an in vitro system. In addition, this protocol could be used to probe the conformation of transporters in cells treated with transport inhibitors in order to better understand their mechanism of action, and potentially dynamic interactions between domains in proteins that are not transporters.
Identifying Protein Interactions with Histone Peptides Using Bio-layer Interferometry
Authors:  Bingbing Ren, Ahmed Mahmoud Mohammed Sayed, Hwei Ling Tan, Yu Keung Mok and Ee Sin Chen, date: 09/20/2018, view: 7200, Q&A: 0
Histone post-translational modifications (PTMs) regulate numerous cellular processes, including gene transcription, cell division, and DNA damage repair. Most histone PTMs affect the recruitment or exclusion of reader proteins from chromatin. Here, we present a protocol to measure affinity and interaction kinetics between histone peptides and the recombinant protein using Bio-layer interferometry.
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