Structural alterations in a type IV pilus subunit protein result in concurrent defects in multicellular behaviour and adherence to host tissue.
The ability of bacteria to establish complex communities on surfaces is believed to require both bacterial-substratum and bacterial-bacterial interactions, and type IV pili appear to play a critical but incompletely defined role in both these processes. Using the human pathogen Neisseria gonorrhoeae, spontaneous mutants defective in bacterial self-aggregative behaviour but quantitatively unaltered in pilus fibre expression were isolated by a unique selective scheme. The mutants, carrying single amino acid substitutions within the conserved amino-terminal domain of the pilus fibre subunit, were reduced in the ability to adhere to a human epithelial cell line. Co-expression of the altered alleles in the context of a wild-type pilE gene confirmed that they were dominant negative with respect to aggregation and human cell adherence. Strains expressing two copies of the altered alleles produced twice as much purifiable pili but retained the aggregative and adherence defects. Finally, the defects in aggregative behaviour and adherence of each of the mutants were suppressed by a loss-of-function mutation in the twitching motility gene pilT. The correlations between self-aggregation and the net capacity of the microbial population to adhere efficiently demonstrates the potential significance of bacterial cell-cell interactions to colonization.
Park
H S
HS
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Wolfgang
M
M
van Putten
J P
JP
Dorward
D
D
Hayes
S F
SF
Koomey
M
M
D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009344:Neisseria gonorrhoeae / Q000235:genetics* / Q000502:physiology* / Q000648:ultrastructure; D021122:Protein Subunits; D016415:Sequence Alignment
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D021122:Protein Subunits; C074063:pilE protein, Neisseria gonorrhoeae; D036781:Fimbriae Proteins