Table 1.
Domains of filamentous phage Ff minor coat protein pIII
| Domain | Amino acids | Function | |
|---|---|---|---|
| SS | 18 | Signal peptide, targeting the polypeptide to the Sec secretion system; cleaved off during secretion | |
| N1 | 67 | Interacts with the inner membrane protein TolQRA during infection | Exposed N-terminal domains |
| L1 | 19 | Flexible linker | |
| N2 | 131 | Binds F pilus to initiate infection | |
| L2 | 39 | Long flexible linker connecting the N-terminal domains to the C-terminal domain C embedded in the pointy tip | |
| C (including TM) | 150 | C-terminal domain: five copies intertwined with five copies of pVI and the C-terminal ends of five copies of pVIII to form the pointy tip. The final 27 residues of C comprise the transmembrane domain TM; prior to incorporation into the virion, the first 21 residues of TM act as a transmembrane helix anchoring pIII in the inner membrane of the host bacterium, with the final six residues of TM exposed in the cytoplasm. | |
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For further details, see Pellegri et al. (2023), and see also Overview: Structure, Biology, and Applications of Filamentous Bacteriophages (Rakonjac et al. 2024).
