B. Sonden et Be. Uhlin, COORDINATED AND DIFFERENTIAL EXPRESSION OF HISTONE-LIKE PROTEINS IN ESCHERICHIA-COLI - REGULATION AND FUNCTION OF THE H-NS ANALOG STPA, EMBO journal, 15(18), 1996, pp. 4970-4980
The histone-like protein H-NS has been shown to influence the regulati
on of gene expression at the transcriptional level in several Escheric
hia coli operons, We have examined the regulation of the stpA gene, wh
ich encodes a protein sharing 58% identity with H-NS, by mRNA analysis
and by using stpA-lacZ operon fusions, The expression of stpA is temp
erature dependent, with 2-fold higher expression at 37 degrees C than
at 26 degrees C, In addition, stpA expression is stimulated by the glo
bal regulator Lrp. In an hns mutant E,coli derivative stpA expression
is derepressed, suggesting that regulation of the two genes is coupled
, Overproduction of the StpA protein affects expression from at least
four hns regulated operons (the papB, proU, bgl and hns operons), in b
oth the presence and absence of H-NS, The construction of E,coli strai
ns carrying mutations in both stpA and hns demonstrated that the absen
ce of both proteins affects growth rate and viability of the cells, Ou
r work establishes that E. coli can express two H-NS-like proteins wit
h coordinated yet differential regulation, Evidently, these proteins h
ave both overlapping and distinct functions in the cell, and they are
both important for normal cell growth and gene control.