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Title: Macromolecular crowding can account for RNase-sensitive constraint of bacterial nucleoid structure

The shape and compaction of the bacterial nucleoid may affect the accessibility of genetic material to the transcriptional machinery in natural and synthetic systems. To investigate this phenomenon, the nature and contribution of RNA and protein to the compaction of nucleoids that had been gently released from Escherichia coli cells were investigated using fluorescent and transmission electron microscopy. We propose that the removal of RNA from the bacterial nucleoid affects nucleoid compaction by altering the branching density and molecular weight of the nucleoid. We show that a common detergent in nucleoid preparations, Brij 58, plays a previously unrecognized role as a macromolecular crowding agent. RNA-free nucleoids adopt a compact structure similar in size to exponential-phase nucleoids when the concentration of Brij 58 is increased, consistent with our hypothesis. We present evidence that control and protein-free nucleoids behave similarly in solutions containing a macromolecular crowding agent. These results show that the contribution to DNA compaction by nucleoid-associated proteins is small when compared to macromolecular crowding effects.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853-5201 (United States)
  2. Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-5201 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22202493
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 395; Journal Issue: 1; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BRANCHING RATIO; DETERGENTS; DNA; ESCHERICHIA COLI; FLUORESCENCE; LIMITING VALUES; MOLECULAR WEIGHT; PROTEINS; RNA; TRANSMISSION ELECTRON MICROSCOPY