Cloning and characterization of the gene encoding the z66 antigen of Salmonella enterica serovar Typhi.
Z66 antigen-positive strains of Salmonella enterica serovar Typhi change flagellin expression in only one direction from the z66 antigen to the d or j antigen, which is different from the phase variation of S. enterica serovar Typhimurium. In the present study, we identified a new flagellin gene in z66 antigen-positive strains of S. enterica serovar Typhi. The genomic structure of the region containing this new flagellin gene was similar to that of fljBA operon of biphasic S. enterica serovars. A fljA-like gene was present downstream of the new flagellin gene. A rho-independent terminator was located between the new flagellin gene and the fljA-like gene. Hin-like gene was not present upstream of the new flagellin gene. We generated a mutant strain of S. enterica serovar Typhi, which carries a deletion of the new flagellin gene. Western blotting revealed that the 51-kDa z66 antigen protein was absent from the population of proteins secreted by the mutant strain. Southern hybridization demonstrated that the z66 antigen-positive strains of S. enterica serovar Typhi carried the new flagellin gene and fliC on two different genomic EcoRI fragments. When z66 antigen-positive strains were incubated with anti-z66 antiserum, the flagellin expression by S. enterica serovar Typhi changed from z66 antigen to j antigen. The new flagellin gene and the fljA-like gene were absent in the strain with altered flagellin expression. These results suggested that the new flagellin gene is a fljB-like gene, which encodes the z66 antigen of S. enterica serovar Typhi, and that deletion of fljBA-like operon may explain why S. enterica serovar Typhi alters the flagellin expression in only one direction from the z66 antigen to the d or j antigen.
Huang
Xinxiang
X
Department of Microbiology and Bioinformatics, Regeneration and Advanced Medical Science, Gifu University School of Medicine, 40 Tsukasa Machi, Gifu 500-8750, Japan.
Phung
Le V
le V
Dejsirilert
Surang
S
Tishyadhigama
Prapawadee
P
Li
Ying
Y
Liu
Hongshen
H
Hirose
Kenji
K
Kawamura
Yoshiaki
Y
Ezaki
Takayuki
T
D000942:Antigens, Bacterial / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D005408:Flagellin / Q000235:genetics; D005798:Genes, Bacterial; D010802:Phylogeny; D012485:Salmonella typhi / Q000145:classification / Q000235:genetics*; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics
D000942:Antigens, Bacterial; D017931:DNA Primers; C487817:z66 antigen, Salmonella enterica; D005408:Flagellin