title: Cyanotryptophans as Novel Fluorescent Probes for Studying Protein Conformational Changes and DNA-Protein Interaction.
abstract: Described herein are the syntheses and photophysical characterization of three novel cyanotryptophans, and their efficient incorporation into proteins as fluorescent probes. Photophysical characteristics indicated that each was significantly brighter and red-shifted in fluorescence emission relative to tryptophan. Each analogue was used to activate a suppressor tRNA transcript and was incorporated with good efficiency into two different positions (Trp22 and Trp74) of Escherichia coli dihydrofolate reductase (ecDHFR). The Trp analogues could be monitored selectively in the presence of multiple native Trp residues in DHFR. 6-CNTrp (A) formed an efficient Förster resonance energy transfer (FRET) pair with l-(7-hydroxycoumarin-4-yl)ethylglycine (HCO, D) at position 17. Further, 6-CNTrp (A) was incorporated into two DNA binding proteins, including the Klenow fragment of DNA polymerase I and an RNA recognition motif (RRM2) of heterogeneous nuclear ribonucleoprotein L-like (hnRNP LL). Using these proteins, we demonstrated the use of FRET involving A as a fluorescence donor and benzo[g]quinazoline-2,4-(1H,3H)-dione 2'-deoxyriboside (Tf) or 4-aminobenzo[g]quinazoline-2-one 2'-deoxyriboside (Cf) as fluorescent acceptors to study the binding interaction of the Klenow fragment with duplex DNA oligomers (labeled with Tf), or the domain-specific association between hnRNP LL and the BCL2 i-motif DNA (labeled with Cf). Thus, the non-natural amino acid could be used as a FRET partner for studying protein-nucleic acid interactions. Together, these findings demonstrate the potential utility of 6-CNTrp (A) as a fluorescence donor for the study of protein conformational events.
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Poulami
authors.initials: P
authors.lastname: Talukder
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Shengxi
authors.initials: S
authors.lastname: Chen
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Basab
authors.initials: B
authors.lastname: Roy
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Petro
authors.initials: P
authors.lastname: Yakovchuk
authors.affiliation: Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Spiering
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Mohammad P
authors.initials: MP
authors.lastname: Alam
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Manikandadas M
authors.initials: MM
authors.lastname: Madathil
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Chandrabali
authors.initials: C
authors.lastname: Bhattacharya
authors.affiliation: Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
authors.affiliation: Center for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Sidney M
authors.initials: SM
authors.lastname: Hecht
mesh_terms: D004247:DNA / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D011506:Proteins; D014364:Tryptophan; D004247:DNA