Unraveling the molecular basis of subunit specificity in P pilus assembly by mass spectrometry.
P pili are multisubunit fibers essential for the attachment of uropathogenic Escherichia coli to the kidney. These fibers are formed by the noncovalent assembly of six different homologous subunit types in an array that is strictly defined in terms of both the number and order of each subunit type. Assembly occurs through a mechanism termed "donor-strand exchange (DSE)" in which an N-terminal extension (Nte) of one subunit donates a beta-strand to an adjacent subunit, completing its Ig fold. Despite structural determination of the different subunits, the mechanism determining specificity of subunit ordering in pilus assembly remained unclear. Here, we have used noncovalent mass spectrometry to monitor DSE between all 30 possible pairs of P pilus subunits and their Ntes. We demonstrate a striking correlation between the natural order of subunits in pili and their ability to undergo DSE in vitro. The results reveal insights into the molecular mechanism by which subunit ordering during the assembly of this complex is achieved.
Rose
Rebecca J
RJ
Astbury Centre for Structural Molecular Biology and Institute of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
Verger
Denis
D
Daviter
Tina
T
Remaut
Han
H
Paci
Emanuele
E
Waksman
Gabriel
G
Ashcroft
Alison E
AE
Radford
Sheena E
SE
D000595:Amino Acid Sequence; D010861:Fimbriae, Bacterial / Q000737:chemistry*; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D021122:Protein Subunits / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D018832:Molecular Chaperones; D010455:Peptides; D021122:Protein Subunits