3eciphering the protein-DNA code of bacteria Ninged helix-turn-helix transcription factors

作     者：Adam P. Joyce James J. Havranek 

作者机构：Program in Developmental Regenerative and Stem Cell Biology Washington University in St. Louis St. Louis MO 63110 USA Department of Biochemistry and Molecular Biophysics Washington University in St. Louis St. Louis MO 63110 USA 

出 版 物：《Frontiers of Electrical and Electronic Engineering in China》 (中国电气与电子工程前沿（英文版）)

年 卷 期：2018年第6卷第1期

页      面：68-84页

核心收录：

学科分类：0710[理学-生物学] 0831[工学-生物医学工程（可授工学、理学、医学学位）] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 08[工学] 0835[工学-软件工程] 071005[理学-微生物学] 0701[理学-数学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 10[医学] 081202[工学-计算机软件与理论] 

基　　金：support of NSF Graduate Research Fellowship Award to A.P.J National Institutes of Health Award to J.J.H 

主　　题：transcription factor SELEX winged helix-turn-helix specificity detenlainants two-component signaling 

摘      要：Background： Sequence-specific binding by transcription factors （TFs） plays a significant role in the selection and regulation of target genes. At the protein：DNA interface, amino acid side-chains construct a diverse physicochemical network of specific and non-specific interactions, and seemingly subtle changes in amino acid identity at certain positions may dramatically impact TF：DNA binding. Variation of these specificity-determining residues （SDRs） is a major mechanism of functional divergence between TFs with strong structural or sequence homology. Methods： In this study, we employed a combination of high-throughput specificity profiling by SELEX and Spec-seq, structural modeling, and evolutionary analysis to probe the binding preferences of winged helix-turn-helix TFs belonging to the OmpR sub-family in Escherichia coil Results： We found that E. coli OmpR paralogs recognize tandem, variably spaced repeats composed of＂GT-A＂ or ＂GCT＂-containing half-sites. Some divergent sequence preferences observed within the ＂GT-A＂ mode correlate with amino acid similarity; conversely, ＂GCT＂-based motifs were observed for a subset of paralogs with low sequence homology. Direct specificity profiling of a subset of OmpR homologues （CpxR, RstA, and OmpR） as well as predicted ＂SDR-swap＂ variants revealed that individual SDRs may impact sequence preferences locally through direct contact with DNA bases or distally via the DNA backbone. Conclusions： Overall, our work provides evidence for a common structural code for sequence-specific wHTH：DNA interactions, and demonstrates that surprisingly modest residue changes can enable recognition of highly divergent sequence motifs. Further examination of SDR predictions will likely reveal additional mechanisms controlling the evolutionary divergence of this important class of transcriptional regulators.