Expression of CFA/I fimbriae is positively regulated.
Production of the plasmid-coded fimbrial antigen CFA/I of Escherichia coli requires both CFA/I region 1 and CFA/I region 2, which are separated by about 40 kb on the wildtype plasmid. The nucleotide sequence of region 2 was determined and contains an open reading frame (cfa d), encoding a protein of 265 amino acids. The protein has no signal sequence and upon sequence analysis appeared to be a DNA-binding protein. A plasmid was constituted, with a promoterless beta-galactosidase gene preceded by the promoter of region 1. Introduction of a plasmid, carrying the cfa d gene, into a strain containing this construct enhanced expression of beta-galactosidase by at least five-fold indicating that the cfa d protein was enhancing expression from the promoter of region 1. The cfa d gene sequence differed at 28 positions from the Rns gene, which encodes a protein that is a positive regulator of the expression of CS1 or CS2 fimbriae. It was shown that the cfa d gene and the Rns gene can functionally substitute each other in regulating fimbrial synthesis.
Savelkoul
P H
PH
Department of Bacteriology, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
Willshaw
G A
GA
McConnell
M M
MM
Smith
H R
HR
Hamers
A M
AM
van der Zeijst
B A
BA
Gaastra
W
W
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005809:Genes, Regulator / Q000235:genetics; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid
D000942:Antigens, Bacterial; D004268:DNA-Binding Proteins; C022924:colonization factor antigens; D036781:Fimbriae Proteins