title: Type 3 fimbriae of Klebsiella sp.: molecular characterization and role in bacterial adhesion to plant roots.
abstract: Type 3 fimbriae of Klebsiella were purified and characterized. The fimbriae were 4 to 5 nm in diameter and 0.5 to 2 microns long. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the fimbrillin had an apparent molecular weight of 23,500, and it differed from enterobacterial type 1 fimbrillins in its amino acid composition. Hydrophobic amino acids comprised 33.6% of all amino acids in the fimbrillin, which lacked cystine, phenylalanine, and arginine. Serologically, the type 3 fimbriae were also distinct from the type 1 fimbriae. Purified type 3 fimbriae agglutinated tannin-treated human blood group O erythrocytes; this confirms the role of type 3 fimbriae as hemagglutinins. Purified 125I-labeled type 3 fimbriae bound to the roots of Poa pratensis, and this binding could be inhibited by Fab fragments to the purified fimbriae. Anti-type 3 fimbriae Fab fragments also inhibited bacterial adhesion to plant roots. These results demonstrate that type 3 fimbriae mediate adhesion of klebsiellas to plant roots. Eight nitrogen-fixing strains of Klebsiella also produced type 3 fimbriae when grown under anaerobic nitrogen fixation conditions. It is proposed that type 3 fimbriae are involved in the establishment of the plant-bacterium association concerning nitrogen-fixing Klebsiella strains.
mesh_terms: D000268:Adhesiveness; D010861:Fimbriae, Bacterial / Q000032:analysis* / Q000276:immunology; D006386:Hemagglutination Tests; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007709:Klebsiella / Q000276:immunology / Q000648:ultrastructure*; D009586:Nitrogen Fixation; D006109:Poaceae / Q000382:microbiology*
chemical_list: D007140:Immunoglobulin Fab Fragments