Identification and sequences of the lipopolysaccharide core biosynthetic genes rfaQ, rfaP, and rfaG of Escherichia coli K-12.

AUTOR(ES)

Parker, C T

RESUMO

The rfa locus of Escherichia coli K-12 includes a block of about 10 closely spaced genes transcribed in the same direction which are involved in synthesis and modification of the hexose region of the lipopolysaccharide core. We have sequenced the first three genes in this block. The function of the first of these genes is unknown, but we have designated it rfaQ on the basis of its location and similarity to other rfa genes. Complementation of Salmonella typhimurium rfa mutants with E. coli rfa restriction fragments indicated that the second and third genes in the block were rfaG and rfaP. The deduced sizes of the RfaQ, RfaG, and RfaP proteins are 36,298, 42,284, and 30,872 Da, respectively, and the proteins are basic and lack extensive hydrophobic domains. RfaQ shares regions of homology with proteins RfaC and RfaF, which are involved in synthesis of the heptose region of the core. Proteins RfaB, RfaG, and RfaK share a region of homology, which suggests that they belong to a second family of Rfa proteins which are thought to be hexose transferases.

Documentos Relacionados

• Role of the rfaG and rfaP genes in determining the lipopolysaccharide core structure and cell surface properties of Escherichia coli K-12.
• Structures of the rfaB, rfaI, rfaJ, and rfaS genes of Escherichia coli K-12 and their roles in assembly of the lipopolysaccharide core.
• Comparison of lipopolysaccharide biosynthesis genes rfaK, rfaL, rfaY, and rfaZ of Escherichia coli K-12 and Salmonella typhimurium.
• Effect of rfaH (sfrB) and temperature on expression of rfa genes of Escherichia coli K-12.
• Identification of the promoter region for the colanic acid polysaccharide biosynthetic genes in Escherichia coli K-12.