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B6db references: 90337949

type Journal Article
authors Meier-Dieter, U.; Starman, R.; Barr, K.; Mayer, H.; Rick, P. D.
title Biosynthesis of enterobacterial common antigen in Escherichia coli. Biochemical characterization of Tn10 insertion mutants defective in enterobacterial common antigen synthesis
journal J Biol Chem
ui 90337949
year (1990)
volume 265
number 23
pages 13490-7.
keywords Acetylglucosamine/metabolism
abstract Twelve independent Tn10 insertion mutants of Escherichia coli K12 were isolated that were defective in the synthesis of enterobacterial common antigen (ECA). The mutants were identified by screening a random pool of Tn10 insertion mutants for their ECA phenotype using a colony- immunoblot assay. All 12 of the Tn10 insertion mutants were found to be located in the chromosomal region of the rff-rfe genes. Four of the Tn10 insertions were in rfe genes while the remaining eight Tn10 insertions were in rff genes. All of the rfe::Tn10 insertion mutants were defective in the synthesis of GlcNAc-pyrophosphorylundecaprenol (C55-PP-GlcNAc, lipid I), the first lipid-linked intermediate involved in ECA synthesis. Biochemical characterization of the rff::Tn10 insertion mutants revealed that they were defective in various steps of ECA synthesis subsequent to the synthesis of lipid I. These defects included: (i) the inability to synthesize UDP-ManNAcA due to Tn10 insertions in the structural genes for UDP-GlcNAc-2-epimerase (rffE) and UDP-ManNAcA (N-acetyl-D-mannosaminuronic acid) dehydrogenase (rffD), (ii) defects in the synthesis of C55-GlcNAc-ManNAcA (lipid II) due to insertion of transposon Tn10 in the structural gene for the UDP- ManNAcA transferase (rffM), (iii) the inability to synthesize TDP- Fuc4NAc (4-acetamido-4,6-dideoxy-D-galactose) due to Tn10 insertions in the structural gene for the transaminase that catalyzes the conversion of TDP-4-keto-6-deoxy-D-glucose to TDP-4-amino-4,6-dideoxy-D-galactose (rffA), and (iv) defects in steps subsequent to the synthesis of C55- GlcNAc-ManNAcA-Fuc4NAc (lipid III). In addition, a re-examination of a mutant possessing the rff-726 lesion revealed that it was defective in the synthesis of lipid III due to a defect in the structural gene for the Fuc4NAc transferase (rffT).
last changed 2002/11/12 16:17

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