TY - JOUR
T1 - The 3D structure of a periplasm-spanning platform required for assembly of group 1 capsular polysaccharides in Escherichia coli
AU - Collins, RG
AU - Beis, Konstantinos
AU - Dong, Changjiang
AU - Botting, Catherine Helen
AU - McDonnell, C
AU - Ford, RC
AU - Clarke, BR
AU - Whitfield, C
AU - Naismith, James Henderson
PY - 2007/2/13
Y1 - 2007/2/13
N2 - Capsular polysaccharides (CPSs) are essential virulence determinants of many pathogenic bacteria. Escherichia coli group 1 CPSs provide paradigms for widespread surface polysaccharide assembly systems in Gram-negative bacteria. In these systems, complex carbohydrate polymers must be exported across the periplasm and outer membrane to the cell surface. Group 1 CPS export requires oligomers of the outer membrane protein, Wza, for translocation across the outer membrane. Assembly also depends on Wzc, an inner membrane tyrosine autokinase known to regulate export and synthesis of group 1 CPS. Here, we provide a structural view of a complex comprising Wzc and Wza that spans the periplasm, connecting the inner and outer membranes. Examination of transmembrane sections of the complex suggests that the periplasm is compressed at the site of complex formation. An important feature of CPS production is the coupling of steps involved in biosynthesis and export. We propose that the Wza-Wzc complex provides the structural and regulatory core of a larger macromolecular machine. We suggest a mechanism by which CPS may move from the periplasm through the outer membrane.
AB - Capsular polysaccharides (CPSs) are essential virulence determinants of many pathogenic bacteria. Escherichia coli group 1 CPSs provide paradigms for widespread surface polysaccharide assembly systems in Gram-negative bacteria. In these systems, complex carbohydrate polymers must be exported across the periplasm and outer membrane to the cell surface. Group 1 CPS export requires oligomers of the outer membrane protein, Wza, for translocation across the outer membrane. Assembly also depends on Wzc, an inner membrane tyrosine autokinase known to regulate export and synthesis of group 1 CPS. Here, we provide a structural view of a complex comprising Wzc and Wza that spans the periplasm, connecting the inner and outer membranes. Examination of transmembrane sections of the complex suggests that the periplasm is compressed at the site of complex formation. An important feature of CPS production is the coupling of steps involved in biosynthesis and export. We propose that the Wza-Wzc complex provides the structural and regulatory core of a larger macromolecular machine. We suggest a mechanism by which CPS may move from the periplasm through the outer membrane.
KW - bacteria
KW - capsule
KW - export
KW - membrane
KW - TRANSMISSION ELECTRON-MICROSCOPY
KW - OUTER-MEMBRANE LIPOPROTEIN
KW - BACTERIAL CHANNEL-TUNNELS
KW - GRAM-NEGATIVE BACTERIA
KW - TYROSINE AUTOKINASE
KW - PROTEIN EXPORT
KW - NEISSERIA-MENINGITIDIS
KW - FUNCTIONAL-ANALYSIS
KW - PILQ SECRETIN
KW - COMPLEX
UR - http://www.scopus.com/inward/record.url?scp=33847779058&partnerID=8YFLogxK
U2 - 10.1073/pnas.0607763104
DO - 10.1073/pnas.0607763104
M3 - Article
SN - 0027-8424
VL - 104
SP - 2390
EP - 2395
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 7
ER -