Mark Ronson was to Amy Winehouse what Quincy Jones was to Michael Jackson.

So when the 35-year-old producer learned that his longtime friend and collaborator had died Saturday at the age of 27, it came as no surprise that Ronson was stricken with grief.

VIDEO: Watch Amy perform at the Grammy Awards

"She was my musical soulmate and like a sister to me," Ronson told his Twitter followers. "This is one of the saddest days of my life."

Ronson -- who's set to marry French model Josephine de La Baume on September 3 -- worked with Winehouse on her Back to Black album in 2007. The following year, the album won five Grammy Awards (including Producer of the Year).

PHOTOS: Amy and other stars who died at 27

Back to Black's backing band, Sharon Jones & the Dap-Kings -- along with the entire Daptone Records family -- tell Us Weekly in a statement: "We are very sad to have lost Amy Winehouse today. She was one of a kind and we were fortunate to have had the chance to make music with her. She was always gracious and a pleasure to work with in the studio and on the road. She brought a lot of people joy with her voice and her irreverent personality. It is a tragedy that she was taken from us so soon when she had much more music to give."

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Salaam Remi, who also has a production credit on Back to Black, added that Saturday was a "very very sad day. Just lost a great friend and a sister."

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