Different in vivo localization of the Escherichia coli proteins CspD and CspA

Two Csp proteins (CspA and CspD) were fused to the green fluorescent protei n GFP and expressed from their natural promoters or from an inducible promo ter. Fluorescence microscopy and computerized image analysis indicate that in Escherichia coli growing at 37 degreesC CspD localizes in the nucleoid l ike the control H-NS while CspA occupies a polar position away from the nuc leoid. Following cold shock CspA maintains its location, while CspD is not sufficiently expressed to permit its localization. The different localizati on of CspA and CspD indicates that these proteins play different roles in t he cell in spite of their extensive structural similarity. (C) 2001 Federat ion of European Microbiological Societies. Published by Elsevier Science B. V. All rights reserved.