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Figure 1.
FIGURE 1. Domain organization of HMW1 and model for TPS.
The HMW1 signal sequence (residues 1-68) is shown in yellow, the
HMW1 pro-piece (residues 69-441) is shown in magenta, and the
mature HMW1 adhesin (442-1536) is shown in blue (a large cell
surface structure) and in orange (a small C-terminal anchor).
For clarity, only the secretion process across the outer
membrane is presented. After Sec-dependent export of the HMW1
preproprotein across the inner membrane, the HMW1 secretion
domain interacts with HMW1B, likely in the periplasm,
facilitating translocation of HMW1 across the outer membrane.
Sometime during this translocation process, HMW1-PP is cleaved
and released to the extracellular space (S. Grass and J. W. St.
Geme III, unpublished data). Ultimately, the binding domain of
mature HMW1 is exposed on the tip of the adhesin, away from the
bacterial cell surface, in a position that favors access to host
cells.
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