Furthermore , PAT DE4 was positive for the outer membrane receptor gene instead of but no signal was obtained for the islet genes htrE ( probable porin/fimbrial assembly protein ) , sopD2 ( secreted effector protein ) , srfJ ( putative virulence factor , activated by transcription factor SsrB ) and sseK2 ( translocated effector protein SSEK2 by type III secretion system ) while pagK ( PhoPQ-activated protein ) was present only in this array type .