Differential decay of RNA of the CFA/I fimbrial operon and control of relative gene expression.
CFA/I fimbriae on human enterotoxigenic Escherichia coli are composed of the CfaB protein, the product of the second gene of the CFA/I operon. We show here that CfaB is expressed at a higher level than other proteins of the CFA/I operon. mRNA encoding the CfaB protein is much more abundant than mRNA encoding CfaA, the first protein, together with CfaB or mRNA encoding CfaA only. Only one promoter, upstream of cfaA, is present. These data indicate that a primary transcript containing cfaA and cfaB is processed into a cfaA-specific mRNA and a cfaB-specific mRNA. The cfaA mRNA is unstable, while the cfaB mRNA is stable and therefore accumulates in CFA/I-producing E. coli. The cfaB mRNA is probably stabilized by a stem-loop structure downstream of the cfaB gene. No distinct mRNA fragments could be detected encoding the other two proteins, CfaC and CfaE, of the CFA/I operon. These results indicate that cfaC- and cfaE-specific mRNAs degrade very rapidly and/or are produced in small amounts.
Jordi
B J
BJ
Department of Bacteriology, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
op den Camp
I E
IE
de Haan
L A
LA
van der Zeijst
B A
BA
Gaastra
W
W
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009876:Operon; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D015183:Restriction Mapping; D014169:Transformation, Bacterial; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; C022924:colonization factor antigens; D036781:Fimbriae Proteins; D001616:beta-Galactosidase