US actress Dakota Johnson will play the naive Anastasia Steele alongside English actor Charlie Hunnam as the manipulative Christian Grey in the film version of the erotic novel Fifty Shades of Grey , its British author, E.L. James, said. "The gorgeous and talented Charlie Hunnam will be Christian Grey in the film adaptation of Fifty Shades of Grey ," James said on her website on Monday, before revealing Johnson's role. Fifty Shades of Grey , about a passionate relationship between student Anastasia and entrepreneur Christian, was first published in 2011 and became a cultural phenomenon as it rocketed up the bestseller lists. Described as "mommy porn" by critics, James's debut novel became Britain's fastest paperback to reach a million sales and was the first in a trilogy. Movie rights for the novels were bought up by Universal Pictures and Focus Features. Johnson, 23, a fashion model and actress, is the daughter of Miami Vice actor Don Johnson and Working Girl star Melanie Griffith. Johnson is best known for films such as 2012 action comedy 21 Jump Street and romantic comedy The Five-Year Engagement .