The rcsA gene of Escherichia coli O9:K30:H12 is involved in the expression of the serotype-specific group I K (capsular) antigen.
AUTOR(ES)
Keenleyside, W J
RESUMO
Escherichia coli produces two distinct types of capsular polysaccharide (designated groups I and II), which are distinguished by chemical, physical, and genetic characteristics. The K30 capsular antigen is a member of the group I, or heat-stable, capsules. We have cloned rcsA from E. coli O9:K30 and determined the nucleotide sequence. The rcsAK30 sequence is virtually identical to the rcsAK-12 sequence (V. Stout, A. Torres-Cabassa, M. R. Maurizi, D. Gutnick, and S. Gottesman, J. Bacteriol. 173:1738-1747, 1991). RcsAK-12 is a transcriptional activator involved in expression of the extracellular polysaccharide colanic acid in E. coli K-12. rcsAK30 complemented an rcsAK-12 mutation and activated colanic acid synthesis in E. coli K-12 strains. However, in E. coli K30, increasing the levels of RcsA by introducing multicopy rcsAK30 or a Lon mutation resulted in elevated synthesis of the K30 capsular polysaccharide; no colanic acid was detected. E. coli K-12 strains in which the chromosomal his region was replaced by that from E. coli K30 were able to synthesize K30 capsular polysaccharide. These K-12/K30 hybrid strains did not produce colanic acid, suggesting that the genes for synthesis of colanic acid and the K30 capsular polysaccharide may be allelic. rcsA sequences were also detected in the group II strains E. coli K1 and K5. Introduction of rcsAK30 into group II strains resulted in activation of colanic acid biosynthesis rather than the group II capsule. Given the role of RcsA in other members of the family Enterobacteriaceae, our results provide further evidence that this protein may be a relatively widespread regulatory component for the synthesis of enterobacterial extracellular polysaccharides.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=205669Documentos Relacionados
- The rcsA gene of Klebsiella pneumoniae O1:K20 is involved in expression of the serotype-specific K (capsular) antigen.
- Characterization of rcsB and rcsC from Escherichia coli O9:K30:H12 and examination of the role of the rcs regulatory system in expression of group I capsular polysaccharides.
- Coexpression of colanic acid and serotype-specific capsular polysaccharides in Escherichia coli strains with group II K antigens.
- Detection of serotype-specific antibodies or capsular antigen of Actinobacillus pleuropneumoniae by a double-label radioimmunoassay.
- A small RNA acts as an antisilencer of the H-NS-silenced rcsA gene of Escherichia coli.