Histone-like proteins in the purified Escherichia coli deoxyribonucleoprotein

Abstract

Analysis of E.col chromosomes isolated under conditions similar to those used for isolation of eukaryotic chromatin has shown that: 1) The proteins of highly purified E.coli de-oxibonucleoprotein are mainly in addition to RNA polymerase two specific histone-like proteins of apparent molecular weight of 17 000 and 9,000 (proteins I and 2, respectively).2) Proteins 4 and 2 occur in approximately equal molar amounts in the isolated E coli chromosome, and their relative content corresponds to one molecule of protein I plus one molecule of protein 2 per 150-200 base pairs of DNA. 3) There are no long stretches of naked DNA in the purified E.coli deozyribonucleoprotein suggesting a fairly uniform distriution of the proteins I and 2 along DNA. 4) The protein 2 is apparently identical to the DNA-binding protein UJ which was isolated previously /1/ from extracts of E.coli cells. 5) Digestion of the isolated E.coli chromosomes itE staphylococcal nuclease proceeds throu-ghdiscrete deoxyribonucleoprotein intermediates (in particular, at~120 base pairs) which contain both proteins 1 and 2. However, since no repeating multimer structure was observed so far in nuclease digests of the E.coli chromosome, it seems premature to draw definite concl-usns about possible similarities between the nucleosomal organization of the eukaryotic chromatin and the E.coli chromatin structure.

Structural Basis for H-NS-mediated Trapping of RNA Polymerase in the Open Initiation Complex at the rrnB P1

“…The antagonistic properties of both regulators largely correlate with their cellular concentrations, which at stationary growth are significant for H-NS (about 20,000 copies per cell) and negligible for FIS (Ͻ100 copies per cell). Both factors bind to overlapping sites upstream of all seven rRNA P1 promoters (49), 2 and mechanistic models for their antagonism based on binding competition studies have been proposed (22). The RNA polymerase-trapping mechanism, which has been documented biochemically 2 A. Hillebrand and R. Wagner, unpublished data.…”

“…The Escherichia coli nucleoid-associated protein H-NS, originally identified as a heat stable transcription factor (1), is one of the major components of the bacterial nucleoid (2,3). It was therefore proposed to be involved in the structural organization of the E. coli chromosome.…”

FIS modulates growth phase‐dependent topological transitions of DNA in Escherichia coli

“…The major nucleoid-associated protein HU has been shown to constrain negative supercoils by compacting the DNA into nucleosome-like structures (Rouviè re-Yaniv et al, 1979;Broyles and Pettijohn, 1986). Another important protein implicated in the structure of the E. coli nucleoid is H-NS (Varshavsky et al, 1977;Spassky et al, 1984;Higgins et al, 1988; reviewed by Ussery et al, 1994), which binds preferentially to curved DNA (Bracco et al, 1989;Yamada et al, 1990;Zuber et al, 1994) and, when overproduced, results in the condensation of bacterial chromosome (Spurio et al, 1992).…”

Inhibition of UV-induced SOS responses by 3-aminobenzamide in Escherichia coli.

“…However, it has been reported that E. coli cells contain histone-like proteins (Varshavsky et al 1979, Hubscher et al 1980) which could possibly be modified by poly(ADP-ribose) synthetase.…”