FAMILY OF THE MAJOR COLD-SHOCK PROTEIN, CSPA (CS7.4), OF ESCHERICHIA-COLI, WHOSE MEMBERS SHOW A HIGH SEQUENCE SIMILARITY WITH THE EUKARYOTIC Y-BOX BINDING-PROTEINS
Sj. Lee et al., FAMILY OF THE MAJOR COLD-SHOCK PROTEIN, CSPA (CS7.4), OF ESCHERICHIA-COLI, WHOSE MEMBERS SHOW A HIGH SEQUENCE SIMILARITY WITH THE EUKARYOTIC Y-BOX BINDING-PROTEINS, Molecular microbiology, 11(5), 1994, pp. 833-839
The cspA is a gene of Escherichia coli, whose expression is specifical
ly induced at low temperatures to a level of 13% of total protein synt
hesis. The CspA protein consisting of 70 amino acid residues has high
sequence similarity with eukaryotic Y-box DNA-binding proteins. We fou
nd two independent clones from the Kohara miniset phage collection, wh
ich hybridized with a DNA fragment containing cspA. DNA sequencing of
these clones confirmed that the two genes are highly homologous to csp
A. One designated cspB is mapped at 35 min on the E. coli chromosome a
nd encodes a 71-residue protein with 79% identity to CspA, while the o
ther, cspC, is mapped at 40 min and encodes a 69-residue protein with
70% identity. In addition, a DNA sequence upstream of the clpA gene at
19 min published elsewhere contains an open reading frame for a 74-re
sidue protein with 45% identity to CspA. All csp genes were fused in t
he coding regions with the lacZ gene, and the expression of beta-galac
tosidase was examined for these hybrid genes upon cold shock. A simila
r cold-shock induction to cspA was observed for cspB but not cspC and
cspA These results indicate that E. coli has a family of the cspA gene
, some of which are induced by cold shock.