Major structure protein of the hrp pilus, which is a component of the type III secretion system (TTSS, Hrp secretion system) required for effector protein delivery, parasitism, and pathogenicity. The hrp pilus functions as a conduit for protein delivery into the host cell. HrpA is required for the secretion of HrpN and DspA/E. Extracellular and secreted via type III secretion system. Belongs to the HrpA type 2 family. Extended N-terminus.