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Selective expression of the β ‐subunit of nucleoid‐associated protein HU during cold shock in Escherichia coli
Author(s) -
Giangrossi Mara,
Giuliodori Anna Maria,
Gualerzi Claudio O.,
Pon Cynthia L.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02868.x
Subject(s) - biology , nucleoid , cold shock domain , transcription (linguistics) , escherichia coli , protein subunit , promoter , gene , gene expression , microbiology and biotechnology , heat shock protein , regulation of gene expression , genetics , rna , linguistics , philosophy
Summary Expression of Escherichia coli hupA and hupB , the structural genes encoding the most abundant nucleoid‐associated proteins HU α and HU β has been studied during cold shock. This article demonstrates that: (i) transcriptional expression of hupA is blocked following a sudden temperature downshift (from 37 ° C to 10 ° C), whereas transcription of hupB from the P2 and P3 promoters is maintained at a constitutive level and is activated de novo from the P4 promoter; (ii) all three hupB mRNAs (transcribed from the three natural promoters P2, P3 and P4) become much more stable than the single hupA transcript; and (iii) the hupB transcripts, unlike that of hupA , are efficiently translated in vivo during cold acclimation and can be actively translated in vitro at low temperature. Taken together, the results indicate that during cold shock the expression of the HU β subunit is preferentially stimulated and that of HU α repressed, suggesting that an altered HU α to HU β expression ratio resulting in an increase of HU α /HU β heterodimers and/or (HU β ) 2 homodimers may play an important role during cold adaptation.