"(Gaga is) an artist through and through. There's no part of her that doesn't understand our job or thinks it's weird. I thinks she's probably the least threatened woman on the planet," Bush said.
The 32-year-old actress, who is in a relationship with Google programme manager Dan Fredinburg, also said that her first encounter with the 28-year-old singer was a little strange.
"It's always a little strange to meet the love of someone's life after you've swapped spit with their partner! But she's just the loveliest human being and so warm and welcoming - I've been such a huge fan of her for so long," she added.