FimY of Salmonella enterica serovar Typhimurium functions as a DNA-binding protein and binds the fimZ promoter.
Salmonella enterica serovar Typhimurium produces type 1 fimbriae with binding specificity to mannose residues. Elements involved in fimbrial structural biosynthesis, transport, and regulation are encoded by the fim gene cluster. FimZ, FimY, FimW, STM0551, and an arginine transfer RNA (fimU) were previously demonstrated to regulate fimbrial expression. The amino acid sequences of the C-terminal portion of FimY revealed similarity with those of LuxR-like proteins. Electrophoretic mobility shift assays indicated that FimY possessed DNA-binding capacity and bound a 605-bp DNA fragment spanning the intergenic region between fimY and fimZ, while a FimY protein harboring a double mutation in the C-terminal helix-turn-helix region containing a glycine (G) to aspartate (D) substitution at residue 189 and isoleucine (I) to lysine (K) substitution at residue 195 lost its ability to bind this DNA fragment. A lux box sequence (5'-TCTGTTATTACATAACAAATACT-3') within the fimZ promoter was required for binding. None of the DNA fragments derived from the promoters for fimA, fimY, or fimW was shifted by FimY. Pull-down assays showed that there were physical protein/protein interactions between FimY and FimZ. We propose that in the regulatory circuit of type 1 fimbriae, FimY functions as a DNA-binding protein to activate fimZ, and a FimY-FimZ protein complex may form to regulate other fim genes. Confirming these proposals requires further study.
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan.
Ke-Chuan
KC
Wang
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan; Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan.
Yuan-Hsun
YH
Hsu
Department of Veterinary Medicine, School of Veterinary Medicine, College of Bioresources and Agriculture, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan.
Yi-Ning
YN
Huang
Department of Veterinary Medicine, School of Veterinary Medicine, College of Bioresources and Agriculture, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan; Division of Animal Medicine, Animal Technology Institute Taiwan, Chunan, Miaoli 35053, Taiwan.
Jiunn-Horng
JH
Lin
Department of Veterinary Medicine, School of Veterinary Medicine, College of Bioresources and Agriculture, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan. Electronic address: ksyeh@ntu.edu.tw.
Kuang-Sheng
KS
Yeh
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D036781:Fimbriae Proteins
DNA binding protein; Salmonella; Type 1 fimbriae