A mechanism is provided for crimping and releasing a suture securing a strip of buttress material to an end effector. The mechanism includes a retention member movably mounted within the end effector. The retention member is movable from a first position crimping the suture to the end effector to a second position releasing the suture from the end effector. The mechanism additionally includes a follower member, engageable with the retention member, and movable in response to actuation of a surgical instrument to move the retention member between the first and second positions. A lock mechanism is also provided to secure the retention member in the first position. The follower member operates to disengage the lock mechanism.