The question was whether it's ok to call an all-in with AKo (both for OP and jmstone). So there isn't any fold equity, and the question is simply whether we have enough equity for the call. Kingkas answered that for OP at 16:27 on 25/2/15: we have 38.8% against his presumed range (in the absence of any information about his 4-bet range) and we need 37.6%, so call is +EV. Unfortunately the rake makes it -EV. The pot we stand to win (after rake) is $19.87 and the cost of calling is $7.83, so the actual equity needed to call is 39.4%. So OP's call on average costs him 12c (and tends to enrich the room at the expense of both players).
As a result I think 4-bet/call is wrong here. 4-bet/fold will be profitable if he is folding more than 73.5% of his 3-bet range here (based on the actual bet sizes). Against unknown I would say that was unlikely. But calling may also be unprofitable for the reason given by excitedpoker, although uglyboy88's line seems worth considering (i.e. call the 3-bet, x/r flop). Another possibility would be to 4-bet straight to all-in. Assuming that he is calling with {AA-QQ, AK}, so the pot equity is as before, I calculate that we need him to fold more than 64.6% of hands for this to be profitable. (64.6% of the time we win the $1.30 in the pot. The remaining 35.4% of the time we have paid $10.08 for a 38.8% chance of winning $19.87 (after rake), which means we lose $2.37 on average. Total EV is therefore zero.)
In jmstone's position, where an unknown pushes immediately over his OR, the pot odds are terrible, as he says. His required bet is 97BB, and the pot after rake will be some 191BB, so he needs some 50.1% equity to call. The problem is that villain's range is very uncertain. Against, say {TT+}, our equity is only 37%. Against {TT+, AJ+}, it is 54.2%. It's a fish move, so his range might be fairly wide, but on balance I think fold is best. Obviously if we've seen him do it before, that might change our decision.