Quaternary Structure of SecA in Solution and Bound to SecYEG Probed at the Single Molecule Level

Ilja Kusters, Geert van den Bogaart, Alexej Kedrov, Victor Krasnikov, Faizah Fulyani, Bert Poolman, Arnold J. M. Driessen*

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

48 Citaten (Scopus)
286 Downloads (Pure)


Dual-color fluorescence-burst analysis (DCFBA) was applied to measure the quaternary structure and high-affinity binding of the bacterial motor protein SecA to the protein-conducting channel SecYEG reconstituted into lipid vesicles. DCFBA is an equilibrium technique that enables the direct observation and quantification of protein-protein interactions at the single molecule level. SecA binds to SecYEG as a dimer with a nucleotide- and preprotein-dependent dissociation constant. One of the SecA protomers binds SecYEG in a salt-resistant manner, whereas binding of the second protomer is salt sensitive. Because protein translocation is salt sensitive, we conclude that the dimeric state of SecA is required for protein translocation. A structural model for the dimeric assembly of SecA while bound to SecYEG is proposed based on the crystal structures of the Thermotoga maritima SecA-SecYEG and the Escherichia coil SecA dinner.

Originele taal-2English
Pagina's (van-tot)430-439
Aantal pagina's10
Nummer van het tijdschrift3
StatusPublished - 9-mrt-2011

Citeer dit