NEW YORK — Anna Caterina Antonacci is an opera star who thrives on defying expectations.

A mesmerizing performer with a supple and lustrous voice, Antonacci seems equally at home in roles written for soprano or for the lower-voiced mezzo-soprano. She has triumphed in one of the most popular of operas, Bizet’s “Carmen,” but mostly she has sought out repertory off the beaten path. And while for many singers, appearing at the Metropolitan Opera represents the pinnacle of success, Antonacci has never sung there, and likely never will.

But though her career is mainly in Europe, she has recently been making annual concert appearances in New York. In March, after she sang a program of French songs and Poulenc’s monodrama “La Voix Humaine,” Zachary Woolfe wrote in The New York Times that “her alertness to the texts and the unassuming grandeur of her presence made the night riveting.”

Now she’s back in the United States again to headline the San Francisco Opera’s summer season, which opens June 7. She will portray her touchstone role of Cassandra in Berlioz’s epic “Les Troyens” and also will star in the world premiere of an opera based on a classic book and film.

In a recent interview with The Associated Press, the 54-year-old Italian singer talked about her unusual career and the roles she most responds to.

Q: How have you approached your choice of roles throughout your career?

A: It’s true that my repertoire is very bizarre. It’s always changing. I started with Rossini and Donizetti and then Mozart, which was quite normal, logical for my age. But then I got into the Baroque with Gluck. For some reason I was always in a repertoire that’s not so well known. It was very interesting to discover this music and these characters, women characters. And then I started with the French repertoire, so it was always this evolution. I’m quite proud of my career, even if at the beginning I couldn’t ever imagine how it would go.

Q: The new opera you’ll be performing in San Francisco, “Two Women” by Italian composer Marco Tutino, is based on a novel by Alberto Moravia that was made into a film for which Sophia Loren won an Oscar. What made you want to create the role of Cesira?

A: She’s an abused woman, very simple, a widow, and she must devote her life to her daughter alone during the war. She meets this man, and she loves him. At the end there is this horrible rape from the soldiers, but she finds the strength to help her daughter turn the page and look to the future. I didn’t like the book very much, but the movie is very beautiful. Maternal love is the strongest thing in the opera. The music is modern but beautiful, it’s like Debussy. For me contemporary music is very difficult, I cannot learn it when you don’t recognize your note, your moment, when there’s no melody.

Q: What do you respond to in the role of Cassandra, the Trojan princess whose prophetic warnings are ignored on the eve of her people’s defeat by the Greeks?

A: The role is such a gift for an interpreter. It’s so thrilling, involving, exciting. I must say this theme of the death of an entire people, the genocide, it really affects me a lot. It’s something I always felt very deeply. It all happens the night before the world ends. For me it’s always very moving, very frightening, catastrophic.

Q: Why have you appeared so seldom in the United States?

A: When I was young in 1988 I took part in the Pavarotti vocal competition in Philadelphia. That was my first time coming here. And then I sang twice in San Francisco, in 1993 (Rossini’s ‘Ermione’) and 1998 (Adalgisa in Bellini’s ‘Norma’). Both were fantastic experiences. With the Met, we had some proposals for some Mozart, but we couldn’t make it work.

Q: What roles would you like to sing that you haven’t yet?

A: Nothing right now. The best things I did in my life were always somebody else’s ideas. I don’t have much imagination, so I always wait for an invitation. Like Cassandra, I never, never would have thought of that. I was doing (Handel’s) ‘Rodelinda’ in Paris and the artistic director told me they wanted to do ‘Les Troyens,’ but differently, not the usual cast with Wagnerian voices, but with singers like me. I said it sounds interesting, of course I will study this. I started listening, discovering. But I couldn’t imagine I would develop this enormous love for the role.