First hand of tournament: big decision

[Toopskees]

$110 multi, about 100 players. Starting chip stack is T2000. Starting blinds are 25/50. First hand of tourney: Folded to me in MP. I get AK and raise to 200, and get 3 callers including the button. The SB and BB fold. Pot size is 875 with 4 players. Flop is A44 rainbow. I lead out with 500. The first 2 callers fold, but the button minraises to T1000. What do you put the button on, and what should my action be?