Table 2.

Functional characteristics of core proteins of the Tn7 family of transposons.

Feature	TnsA	TnsB	TnsC	TnsD	TnsE
Functional characteristics	Cleavage of 5’ terminal DNA	Cleavage of 3’ terminal DNA and strand transfer	Regulates transposition, recruits TnsAB	Recognizes the attTn7 safe site	Recognizes replication fork, facilitates horizontal transfer
Unique feature	Restriction endonuclease-like	DDE catalytic motif	ATPase, mediates target immunity	Sequence-specific binding	Structure-specific DNA binding
Target site/recognition object	Outside of 5’ transposon end	Left and right terminal sequences of transposon	Target DNA and TnsD/E	Downstream of glmS gene (attTn7)	DNA replication fork structure
Regulatory mechanism	Forms heterodimer with TnsB	Cooperates with TnsA for transposition	ATP hydrolysis drives conformational change	Interacts with TnsC to guide insertion	Preferentially inserts into conjugative plasmids
References	(Sarnovsky et al., 1996; Peters, 2014)	(Sarnovsky et al., 1996; Peters, 2014)	(Stellwagen and Craig, 1997; Peters, 2014; Leyva Camacho et al., 2025)	(Parks and Peters, 2007; Peters, 2014; Leyva Camacho et al., 2025)	(Parks and Peters, 2007; Peters, 2014; Krishnan et al., 2025)