Sep 18, 2003

A novel outer membrane protein, Wzi, is involved in surface assembly of the Escherichia coli K30 group 1 capsule

Journal of Bacteriology
Andrea RahnChris Whitfield


Escherichia coli group 1 K antigens form a tightly associated capsule structure on the cell surface. Although the general features of the early steps in capsular polysaccharide biosynthesis have been described, little is known about the later stages that culminate in assembly of a capsular structure on the cell surface. Group 1 capsule biosynthesis gene clusters (cps) in E. coli and Klebsiella pneumoniae include a conserved open reading frame, wzi. The wzi gene is the first of a block of four conserved genes (wzi-wza-wzb-wzc) found in all group 1 K-antigen serotypes. Unlike wza, wzb, and wzc homologs that are found in gene clusters responsible for production of exopolysaccharides (i.e., predominantly cell-free polymer) in a range of bacteria, wzi is found only in systems that assemble capsular polysaccharides. The predicted Wzi protein shows no similarity to any other known proteins in the databases, but computer analysis of Wzi predicted a cleavable signal sequence. Wzi was expressed with a C-terminal hexahistidine tag, purified, and used for the production of specific antibodies that facilitated localization of Wzi to the outer membrane. Circular dichroism spectroscopy indicates that Wzi consists primarily of a beta-barrel st...Continue Reading

  • References35
  • Citations29


Mentioned in this Paper

Pathologic Cytolysis
Establishment and Maintenance of Localization
Joint Capsule
Gene Expression Regulation, Bacterial
In Vivo NMR Spectroscopy
Alkalescens-Dispar Group
Carboxy-Terminal Amino Acid
Outer Membrane

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