Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
SCANNING FORCE MICROSCOPY OF ESCHERICHIA-COLI RNA-POLYMERASE - SIGMA(54) HOLOENZYME COMPLEXES WITH DNA IN BUFFER AND IN AIR
Autore:
SCHULZ A; MUCKE N; LANGOWSKI J; RIPPE K;
Indirizzi:
DEUTSCH KREBSFORSCHUNGSZENTRUM,BIOPHYS MAKROMOL ABT,NEUENHEIMER FELD 280 D-69120 HEIDELBERG GERMANY DEUTSCH KREBSFORSCHUNGSZENTRUM,BIOPHYS MAKROMOL ABT D-69120 HEIDELBERG GERMANY
Titolo Testata:
Journal of Molecular Biology
fascicolo: 4, volume: 283, anno: 1998,
pagine: 821 - 836
SICI:
0022-2836(1998)283:4<821:SFMOER>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACID RESTRICTION FRAGMENTS; 3-DIMENSIONAL STRUCTURE; AQUEOUS-SOLUTIONS; PROMOTER SEARCH; BINDING; TRANSCRIPTION; PROTEIN; MICA; VISUALIZATION; LOCATION;
Keywords:
PROTEIN-DNA INTERACTION; TRANSCRIPTION; RNA POLYMERASE; ATOMIC FORCE MICROSCOPY; TAPPING IN FLUID;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
48
Recensione:
Indirizzi per estratti:
Citazione:
A. Schulz et al., "SCANNING FORCE MICROSCOPY OF ESCHERICHIA-COLI RNA-POLYMERASE - SIGMA(54) HOLOENZYME COMPLEXES WITH DNA IN BUFFER AND IN AIR", Journal of Molecular Biology, 283(4), 1998, pp. 821-836

Abstract

Scanning force microscopy (SFM) was used to visualize complexes of Escherichia coli RNA polymerase(.)sigma(54) (RNAP (.)sigma(54)) and a 1036 base-pair linear DNA fragment containing the glnA promoter. In order to preserve the native hydration state of the protein-DNA complexes,the samples were injected directly into the SFM fluid cell and imagedin buffer. With this protocol, an apparent bending angle of 26(+/-34)degrees was determined for the specific complexes at the promoter. Thebending angle of the unspecifically bound RNAP (.) sigma(54) showed asomewhat broader distribution of 49(+/-48)degrees, indicating the existence of conformational differences as compared to the closed complex. In about two-thirds of the closed complexes, the RNA polymerase holoenzyme was located in a lateral position with respect to the DNA and the bend of the DNA was pointing away from the protein. This conformation was consistent with the finding that for the complexes at the promoter, the apparent contour length was reduced by only about 6 run in buffer as compared to the free DNA. From these results we conclude that in the closed complex of RNAP (.) sigma(54), the DNA was not wrapped around the polymerase, and we present a model for the trajectory of theDNA with respect to the RNA polymerase. The images acquired in bufferwere compared to samples that were washed with water and then dried before imaging. Two artefacts of the washing and drying process were detected. First, extensive washing of the sample reduced the number of the specific complexes bound at the promoter (closed complex of RNAP(.)sigma(54)) from about 70% to 30%. This is likely to be a result of sliding of the RNAP sigma(54) holoenzyme along the DNA induced by the washing process. Second, the apparent DNA shortening of the contour length of RNAP sigma(54)-DNA complexes at the promoter as compared to the contour length of the free DNA was 22 nm for the dried samples as opposed to only 6 nm for the undried samples imaged in buffer. This suggests an artefact of the drying process. (C) 1998 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/10/20 alle ore 04:19:30