Fig. 1.

Relevant features of the PilX protein and the PilX variants. Sequence of the mature PilX protein is from N. meningitidis strain 8013. The boxed N-terminal 27 residues represent the hydrophobic part of PilX highly conserved in N. gonorrhoeae pilin (upper sequence). A 28-aa region of PilX was truncated, as depicted by arrow, to facilitate crystallization. The surface-exposed hydrophobic residues in the D-region that were exchanged for serines are identified by *, whereas those that were deleted are indicated by thick gray lines.