title: DNA looping-dependent autorepression of LEE1 P1 promoters by Ler in enteropathogenic Escherichia coli (EPEC).
abstract: Ler, a homolog of H-NS in enteropathogenic Escherichia coli (EPEC), plays a critical role in the expression of virulence genes encoded by the pathogenic island, locus of enterocyte effacement (LEE). Although Ler acts as an antisilencer of multiple LEE operons by alleviating H-NS-mediated silencing, it represses its own expression from two LEE1 P1 promoters, P1A and P1B, that are separated by 10 bp. Various in vitro biochemical methods were used in this study to elucidate the mechanism underlying transcription repression by Ler. Ler acts through two AATT motifs, centered at position -111.5 on the coding strand and at +65.5 on the noncoding strand, by simultaneously repressing P1A and P1B through DNA-looping. DNA-looping was visualized using atomic force microscopy. It is intriguing that an antisilencing protein represses transcription, not by steric exclusion of RNA polymerase, but by DNA-looping. We propose that the DNA-looping prevents further processing of open promoter complex (RPO) at these promoters during transcription initiation.
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;
authors.forename: Abhayprasad
authors.initials: A
authors.lastname: Bhat
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;Laboratory of Plasma Membrane and Nuclear Signaling, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan;
authors.forename: Minsang
authors.initials: M
authors.lastname: Shin
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;
authors.forename: Hyung-Ju
authors.initials: HJ
authors.lastname: Lim
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea;
authors.forename: Joon Haeng
authors.initials: JH
authors.lastname: Rhee
authors.affiliation: Department of Microbiology, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea;
authors.forename: Soon-Young
authors.initials: SY
authors.lastname: Paik
authors.affiliation: Laboratory of Plasma Membrane and Nuclear Signaling, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan;
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
authors.affiliation: Department of Biomedical Informatics and.
authors.forename: Toru
authors.initials: T
authors.lastname: Tobe
authors.affiliation: Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan; and.
authors.forename: Hilo
authors.initials: H
authors.lastname: Yen
authors.affiliation: Single Molecule Biology Laboratory, School of Life Sciences, Gwangju Institute of Science and Technology, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Gwangrog
authors.initials: G
authors.lastname: Lee
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Kwangju 501-746, South Korea; hyonchoy@jnu.ac.kr.
authors.forename: Hyon E
authors.initials: HE
authors.lastname: Choy
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D056426:Genetic Loci / Q000502:physiology*; D009876:Operon / Q000502:physiology; D020218:Response Elements / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D061785:Transcription Initiation, Genetic / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C465556:Ler protein, E coli; D015534:Trans-Activators
keywords: DNA-bending; first phosphodiester bond formation; road block transcript