Transistor for USB Hub power control
You want to use a P-channel MOSFET for the high side power switching. Connect the source terminal to the +5V and the drain terminal to the USB load. There are a multitude of devices to choose from but you could look at something like a NTR3A052PZT1G from OnSemiconductor. It is nice part rated at a couple of amps in a small SOT23 package. 

You will have to do some looking at the hub chip output. If its power switch output control does not swing up to near 5V (data sheet only promises 2.4V) then you will have to provide some extra circuitry to translate that output to a full 5V swing. This is needed because you want to pull the gate terminal of the P-FET all the way up to the 5V rail to ensure that it turns off. 

(The extra circuitry involved to take care of the P-FET gate drive may very well drive you toward using a regular USB power control chip as everything would be taken care of in a nice small SO-8 package including a compatible logic input for the power control. If you go this route make sure select a chip with active low enable because there are also chips with active high enables).

If you have a pullup resistor on the PWR switch control output make sure to select it so that when the output is low and the pullup is dropping 5V that the current does not exceed the current rating of the HUB output.