Chiba/Engeneering Flagella

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Affinity Tags

Our Aim

Fig. 9 Affinity tags.

To make affinity tags on E.coli, we focused on their flagella that are located outside the cells. We used the following mechanisms:

  • Display sticky peptides in flagellar filament.
  • His-tag. The imidazole group in histidines make a complex with metal ions. 

We combined these two and made a His-tagged flagella in the hope to stick them together via metal ions.

[http://www.npn.jst.go.jp/index.html About flagella]

E.Coli have 5-10 flagella. The flagella is used for swimming and for chemotaxis; the bacteria run when they find attractant, tumble when there is a repellent.

E.coli flagella consist of three parts: a basal body, a hook, and a filament. The filament of E.Coli is a rigid, helical, and cylindrical structure which is 10-15μm long and 23nm thick in diameter. It is built from ~20000 subunits of a ~55kDa single protein, FliC. FliC has three domains, D1,D2,D3; although D1 and D2 are needed for the formation of the functional flagellar filament, D3 domain which sticks outside of the fillament are not essential[3].

"Variable" FliC D3 domain

It is reported that the proteins up to 49.4kDa could be displayed on the cell surface of E.Coli using flagellin fusion protein.[4]

About Histidine Tag

See [http://en.wikipedia.org/wiki/His-tag wikipedia article].

Experiments

Making FliC-his gene

  • We inserted the short peptide with six histidine (“His-Tag”) into the fliC D3 domain.
Fig.10 flic his gene

  • Chiba check.png Sequence Confirmed
  • Chiba check.png Swarm Confirmed
  • Chiba check.png Flagella strained with anti-flagella antibody

Checking the "Stickiness": Beads Adsorption

Purpose

Confirm that the his-tags are displaied on the flagella and are capable of binding to Co2+- or Ni2+- surface.

Samples

  • ⊿fliC strain(JW1908 in KEIO collections [5]) transformed with
    • pUC19-fliC-his
    • no plasmid
  • ⊿fliC,⊿motB strain(GI826)transformed with
    • pUC19-fliC-his
    • no plasmid


Testing Procedure

  1. pUC19-FliC-His was transformed to JW1908(fliC), JW0747(MotB), and GI826(fliC motB).
  2. Grown to stationary phase
  3. Culture suspended with Dynabeads (Metal-IDA), allowing to the affinity adsorption
  4. Beads washed with a phosphate buffer (x4)
  5. E" coli" detached from beads by adding imidazole then spreaded on agar plates.
  6. The number of the colonies on resultant plates.

Results&Discussion

1.Stickiness check using FliC strain

Fig. 11 Binding test using Strain JW1908(⊿fliC,).

  • Cell without His-FliC bound better to the Beads? No way!
  • We thought the problem might be the super-fast revolution of flagella itself. We decided to try MotB strain.


2.Stickiness check using MotB strain

fig. 12 Binding test using Strain JW0747(⊿motB).

  • Mot B deletion provides cell with the flagella completely assembled but not rotating.
  • This time everything worked out! Only in the presence of Co2+Bacteria with His-FliC sticked to the Co-IDA beads very well.
  • In this strain, FliC-His is assembled with wildtype FliC coded in genomic DNA. Nevertheless, the binding efficiency was at the same level (not shown). it seems that His-Tag displayed on the flagella is enough to do its work.
  • On the other hand, the deletion of MotB turned out to be vital for sticking the tagged flagella together.
  • In the presence of FliC-His, cobalt ion adsorb bacteria stronger than nickel ion, this was more or less the expected result.



References

3. Kuwajima, G. et al.: J. Bacteriol., 170, 3305-3309 (1988)
4. Ezaki, S. et. al.: J. Ferment. Bioeng., 86, 500-503 (1998)
5. Baba, T. et. al.: Mol. Systems. Biol., 21, 1-10 (2006)