Components and dynamics of fiber formation define a ubiquitous biogenesis pathway for bacterial pili.
Type IV pili (Tfp) are a unique class of multifunctional surface organelles in Gram-negative bacteria, which play important roles in prokaryotic cell biology. Although components of the Tfp biogenesis machinery have been characterized, it is not clear how they function or interact. Using Neisseria gonorrhoeae as a model system, we report here that organelle biogenesis can be resolved into two discrete steps: fiber formation and translocation of the fiber to the cell surface. This conclusion is based on the capturing of an intermediate state in which the organelle is retained within the cell owing to the simultaneous absence of the secretin family member and biogenesis component PilQ and the twitching motility/pilus retraction protein PilT. This finding is the first demonstration of a specific translocation defect associated with loss of secretin function, and additionally confirms the role of PilT as a conditional antagonist of stable pilus fiber formation. These findings have important implications for Tfp structure and function and are pertinent to other membrane translocation systems that utilize a highly related set of components.
Wolfgang
M
M
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
van Putten
J P
JP
Hayes
S F
SF
Dorward
D
D
Koomey
M
M
D000251:Adenosine Triphosphatases; D000483:Alleles; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology; D008854:Microscopy, Electron; D008954:Models, Biological; D020409:Molecular Motor Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D009344:Neisseria gonorrhoeae / Q000235:genetics / Q000502:physiology; D010641:Phenotype; D012633:Secretin / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D020409:Molecular Motor Proteins; C074063:pilE protein, Neisseria gonorrhoeae; C084295:pilQ protein, bacteria; D012633:Secretin; D036781:Fimbriae Proteins; D000251:Adenosine Triphosphatases