(A) Schematic to explain the constructs, showing the promoter regions cloned in lacZ fusions. The arrow indicates the P2 transcription start site. (B) β-Galactosidase activity level associated with putative promoter regions of Tn4401a, Tn4401b, and Tn4401h isoforms (putative promoters P1, P1+IVS, P2, and P+IVS). lacZ reporter plasmid pRS551 (vector) served as a negative control. Among the reporter constructs, P2 had significantly higher β-galactosidase activity than vector, P1, and P1+IVS (P < 0.05); P2+IVS had significantly higher β-galactosidase activity than P2, P1, and P1+IVS (Student t test, P < 0.05); and promoter sequence Tn4401a had significantly higher β-galactosidase activity than P2+IVS (P < 0.05).