Multiple Flagellin Proteins Have Distinct and Synergistic Roles inAgrobacterium tumefaciensMotility

Abstract

31Rotary flagella propel bacteria through liquid and across semi-solid environments. 32Flagella are composed of the basal body that constitutes the motor for rotation, the 33 curved hook that connects to the basal body, and the flagellar filament that propels the 34 cell. Flagellar filaments can be comprised of a single flagellin protein such as in 35 Escherichia coli or with multiple flagellins such is in Agrobacterium tumefaciens. The 36 four distinct flagellins FlaA, FlaB, FlaC and FlaD produced by wild type A. tumefaciens, 37 are not redundant in function, but have specific properties. FlaA and FlaB are much 38 more abundant than FlaC and FlaD and are readily observable in mature flagellar 39 filaments, when either FlaA or FlaB is fluorescently labeled. Cells having FlaA with any 40 one of the other three flagellins can generate functional filaments and thus are motile, 41 but FlaA alone cannot constitute a functional filament. In flaA mutants that manifest 42 swimming deficiencies, there are multiple ways by which these mutations can be 43 phenotypically suppressed. These suppressor mutations primarily occur within or 44 upstream of the flaB flagellin gene or in the transcriptional factor sciP regulating flagellar 45 expression. The helical conformation of the flagellar filament appears to require a key 46 asparagine residue present in FlaA and absent in other flagellins. However, FlaB can be 47 Importance 51 Flagellins are abundant bacterial proteins comprising the flagellar filaments that propel 52 bacterial movement. Several members of the Alphaproteobacterial group express 53 multiple flagellins, in contrast to model systems such as Escherichia coli that has only 54 one flagellin protein. The plant pathogen Agrobacterium tumefaciens has four flagellins, 55 the abundant and readily detected FlaA and FlaB, and lower levels of FlaC and FlaD. 56 Mutational analysis reveals that FlaA requires at least one of the other flagellins to 57 function -flaA mutants produce non-helical flagella and cannot swim efficiently. 58 Suppressor mutations can rescue this swimming defect through mutations in the 59 remaining flagellins, including structural changes imparting flagellar helical shape, and 60 putative regulators. Our findings shed light on how multiple flagellins contribute to 61 motility. 62 63 sphaeroides has one flagellum (laterally positioned on the cell) that is made up of a 87 single flagellin protein (9, 10). On the other hand, examples of bacteria with filaments 88 made of multiple flagellins include Caulobacter crescentus, which has a single polar 89 flagellum, but remarkably six flagellin proteins (11). Within the Rhizobiaceae family 90 Sinorhizobium meliloti, Rhizobium leguminosarum, Agrobacterium sp. H13-3, and 91 Agrobacterium tumefaciens all encode multiple flagellins. A. tumefaciens mutated in 92 three of its four flagellin genes is reduced in virulence by about 38% and Agrobacterium 93 sp. H13-3 lacking all of its three flagellin genes is resistant to flagella-specific phage 94 infection (12-16). F...

Ligilactobacillus agilis BKN88 possesses thermo-/acid-stable heteropolymeric flagellar filaments

“…This means that loss of either flagellin does not impair motility. Agrobacterium tumefaciens requires multiple kinds of flagellins for functional flagellation [18]. In Vibrio vulnificus, a lack of certain flagellins can result in malfunction of motility, adhesion and cytotoxicity [20].…”

“…Salmonella enterica serovar Typhimurium has two different flagellin genes which are not concurrently expressed [8][9][10][11][12]. In contrast, other bacteria with multiple flagellin genes such as Agrobacterium tumefaciens, Bacillus thuringiensis, Caulobacter crescentus, Campylobacter jejuni and Vibrio species form flagellar filaments composed of mixed different flagellin subunits [4,[13][14][15][16][17][18][19][20][21][22]. Although the individual roles of each flagellin in a bacterium with multiple flagellins have not been clearly described, the flagellins are known to be involved in motility, adhesion or virulence [4,14,19,21,[23][24][25].…”

Comparative analysis of ionic strength tolerance between freshwater and marine Caulobacterales adhesins

“…Different bacterial species harbor an adhesive holdfast and use it to attach to surfaces (2, 3, 9, 49, 50). They represent an extremely diverse group in terms of their physiology and the natural environments they inhabit (soil, freshwater, and marine environments).…”