ORLANDO — The Marlins continued to shake up their roster Tuesday, making their biggest move of the off-season by trading power-hitting second baseman Dan Uggla to Atllanta for infielder Omar Infante and left-handed reliever Mike Dunn.

The Marlins might be close to signing free agent catcher John Buck. He was an All-Star last season with Toronto in his only season there. He hit .281 with 20 homers and 66 RBI.

Last week, the Marlins dealt inconsistent starter Andrew Miller to Boston and center fielder Cameron Maybin to San Diego. In both cases, the Marlins received relief pitchers.

The Marlins went into the general managers’ meetings this week apparently determined to trade Uggla, who was eligible for arbitration this winter. If he hadn’t signed a long-term deal, he could have become a free agent after the 2011 season.

The Marlins got Uggla in 2005 as an inexpensive Rule 5 draft pick.

“Maybe the best $50,000 we ever spent,’ said Larry Beinfest, the Marlins’ president of baseball operations.

Beinfest said the club made a sincere effort to sign Uggla to a long-term deal. He is believed to have rejected a four-year, 48 million offer.

“We offered him multiple years and multiple millions of dollars to remain a Marlin into free agency and we think we more than fairly reflected his accomplishments and production in that offer,” Beinfest said. “We think the compensation would have placed him with the elite players at his position. Dan saw it otherwise and we weren’t able to come to an agreement.”