Two genes, designated (regulation of capsule synthesis) and , that had been cloned from the chromosome of () capsular serotype K21 were capable of activating expression of colanic acid capsular polysaccharide in K12. The gene encoded a polypeptide of 23 kDa that was required for the induction of a mucoid phenotype at ≤ 30 °C but not at ≥ 37 °C. The locus encoded no apparent polypeptides and was not capable by itself of causing the overproduction of colanic acid. However, when present in the same cell with , either or caused expression of mucoidy in at all growth temperatures. These findings are best explained if the gene product acts as a positive regulator of colanic acid biosynthesis in and that activity of this protein is in turn subject to regulation by Lon protease. The locus may exert its effect by preferentially binding a negative regulator of capsular biosynthesis, possibly Lon itself. DNA sequences homologous to the K21 b and genes were found in the genomes of all other capsular serotypes of klebsiellae examined, including K2, K12, K36 and K43. However, there was no homology between such genes and the chromosome of The ability of these genes to induce a mucoid phenotype explains the apparent conjugative transfer from klebsiellae to of the ability to produce K21 or other capsular polysaccharides that are structurally and antigenically related to colanic acid.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error