One of the three PilY1 homologs of X.fastidiosa, which are involved in bacterial twitching motility as component of the filamentous type IV pili (T4P). The twitching motility of this protein is enhanced by calcium, which may provide the bacterium an adaptive advantage in environments with high calcium concentrations. Expression is not affected by calcium. Shows twitching motility. Loss of increased twitching motility at higher Ca(2+) concentrations. Forms T4P. Impaired in the calcium-mediated increase in single-cell attachment to surfaces, but biofilm formation is not affected. Belongs to the PilY1 family.