MPG Office Trust has placed mortgage loans on U.S. Bank Tower and a second downtown high rise in special-servicing status, a move that will allow the troubled REIT to renegotiate terms of the buildings’ debt.

The 72-story US Bank Tower at 633 W. Fifth St., once known as Library Tower, is considered the tallest building west of the Mississippi and has a mortgage that totals $250 million. The second building, the 54-story Wells Fargo Tower at 333 S. Grand St., has $550 million mortgage. It is part of the Wells Fargo Center.

Loan special servicers negotiate with lenders on buildings that are in or close to default. Neither building is currently in default, MPG said.

Last week, MPG delivered a notice of imminent default on Gas Company Tower, a 52-story building at 555 West Fifth St. with 1.3 million square feet of space, requesting that it also be placed in special servicing status. Its mortgage totals $458 million.

The largest owner and operator of Class A office properties in the central business district, MPG has struggled to meet loan payments since vacancies rose and rents declined since the recession. It got into trouble after it saddled itself with debt to buy a portion of Equity Office Properties’ Southern California portfolio for roughly $3 billion at the height of the market in 2007.

MPG, formerly known as Maguire Properties Trust has been working with lenders for months to sell non-core assets in Los Angeles and Orange counties so it can hang on to its trophy properties until the market recovers.

The company said in an announcement this week that it “remains optimistic about the prospects for downtown Los Angeles as a whole and for its core portfolio.”

Shares closed up 10 cents, or 3 percent, to $3.50 on the New York Stock Exchange.