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Keywords:

  • Cold shock protein D;
  • Cold shock protein A;
  • In vivo localization;
  • Cold shock;
  • H-NS;
  • Green fluorescent protein fusion;
  • Fluorescence microscopy

Abstract

Two Csp proteins (CspA and CspD) were fused to the green fluorescent protein GFP and expressed from their natural promoters or from an inducible promoter. Fluorescence microscopy and computerized image analysis indicate that in Escherichia coli growing at 37°C CspD localizes in the nucleoid like the control H-NS while CspA occupies a polar position away from the nucleoid. Following cold shock CspA maintains its location, while CspD is not sufficiently expressed to permit its localization. The different localization of CspA and CspD indicates that these proteins play different roles in the cell in spite of their extensive structural similarity.