TY - JOUR A1 - Wawrzinek, Robert A1 - Ziomkowska, Joanna A1 - Heuveling, Johanna A1 - Mertens, Monique A1 - Herrmann, Andreas A1 - Schneider, Erwin A1 - Wessig, Pablo T1 - DBD Dyes as Fluorescence Lifetime Probes to Study Conformational Changes in Proteins JF - CHEMISTRY-A EUROPEAN JOURNAL N2 - Previously, [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD)-based fluorophores used as highly sensitive fluorescence lifetime probes reporting on their microenvironmental polarity have been described. Now, a new generation of DBD dyes has been developed. Although they are still sensitive to polarity, in contrast to the former DBD dyes, they have extraordinary spectroscopic properties even in aqueous surroundings. They are characterized by long fluorescence lifetimes (10-20ns), large Stokes shifts (approximate to 100nm), high photostabilities, and high quantum yields (>0.56). Here, the spectroscopic properties and synthesis of functionalized derivatives for labeling biological targets are described. Furthermore, thio-reactive maleimido derivatives of both DBD generations show strong intramolecular fluorescence quenching. This mechanism has been investigated and is found to undergo a photoelectron transfer (PET) process. After reaction with a thiol group, this fluorescence quenching is prevented, indicating successful bonding. Being sensitive to their environmental polarity, these compounds have been used as powerful fluorescence lifetime probes for the investigation of conformational changes in the maltose ATP-binding cassette transporter through fluorescence lifetime spectroscopy. The differing tendencies of the fluorescence lifetime change for both DBD dye generations promote their combination as a powerful toolkit for studying microenvironments in proteins. KW - dyes KW - pigments KW - electron transfer KW - fluorescent probes KW - maleimides KW - MalF KW - photoelectron transfer Y1 - 2013 U6 - https://doi.org/10.1002/chem.201302368 SN - 0947-6539 SN - 1521-3765 VL - 19 IS - 51 SP - 17349 EP - 17357 PB - WILEY-V C H VERLAG GMBH CY - WEINHEIM ER - TY - JOUR A1 - Heuveling, Johanna A1 - Frochaux, Violette A1 - Ziomkowska, Joanna A1 - Wawrzinek, Robert A1 - Wessig, Pablo A1 - Herrmann, Andreas A1 - Schneider, Erwin T1 - Conformational changes of the bacterial type I ATP-binding cassette importer HisQMP(2) at distinct steps of the catalytic cycle JF - Biochimica et biophysica acta : Biomembranes N2 - Prokaryotic solute binding protein-dependent ATP-binding cassette import systems are divided into type land type II and mechanistic differences in the transport process going along with this classification are under intensive investigation. Little is known about the conformational dynamics during the catalytic cycle especially concerning the transmembrane domains. The type I transporter for positively charged amino acids from Salmonella enterica serovar Typhimurium (1A0-Hi5QMP2) was studied by limited proteolysis in detergent solution in the absence and presence of co-factors including ATP, ADP, LAO/arginine, and Mg2+ ions. Stable peptide fragments could be obtained and differentially susceptible cleavage sites were determined by mass spectrometry as Lys-258 in the nucleotide-binding subunit, HisP, and Arg-217/Arg-218 in the transmembrane subunit, HisQ In contrast, transmembrane subunit HisM was gradually degraded but no stable fragment could be detected. HisP and HisQ were equally resistant under pre- and post-hydrolysis conditions in the presence of arginine-loaded solute-binding protein LAO and ATP/ADP. Some protection was also observed with LAO/arginine alone, thus reflecting binding to the transporter in the apo-state and transmembrane signaling. Comparable digestion patterns were obtained with the transporter reconstituted into proteoliposomes and nanodiscs. Fluorescence lifetime spectroscopy confirmed the change of HisQ(R218) to a more apolar microenvironment upon ATP binding and hydrolysis. Limited proteolysis was subsequently used as a tool to study the consequences of mutations on the transport cycle. Together, our data suggest similar conformational changes during the transport cycle as described for the maltose ABC transporter of Escherichia coli, despite distinct structural differences between both systems. KW - ABC transporter KW - Type I importer KW - Histidine transport KW - Limited proteolysis KW - Fluorescence lifetime KW - Altemate access model Y1 - 2014 U6 - https://doi.org/10.1016/j.bbamem.2013.08.024 SN - 0005-2736 SN - 0006-3002 VL - 1838 IS - 1 SP - 106 EP - 116 PB - Elsevier CY - Amsterdam ER -