By Daren Butler and Ali Kucukgocmen

ISTANBUL (Reuters) -President Tayyip Erdogan on Friday appointed Hafize Gaye Erkan, a finance executive in the United States, to head Turkey's central bank as it prepares to reverse course and tighten policy after years of rate cuts and a simmering cost-of-living crisis.

Erkan, former co-CEO at First Republic Bank and managing director at Goldman Sachs, takes the reins after Erdogan's re-election on May 28 and just under a week after he signalled a pivot away from unorthodoxy with a new cabinet.

The fifth central bank chief in four years, the 43-year-old replaces Sahap Kavcioglu, who spearheaded Erdogan's rate-cutting drive that set off a historic currency crash in 2021 and sent inflation to a 24-year peak above 85% last year.

The announcement of Erkan's appointment in the Official Gazette was accompanied by a decision to appoint Kavcioglu as head of the country's BDDK banking watchdog.

Erkan's leanings are unclear given she has no formal monetary policy experience in her career spanning Wall Street and U.S. corporate boardrooms. She has a Ph.D. from Princeton University in financial engineering.

She was at First Republic from 2014-2021, according to her LinkedIn profile. This year, it became the largest U.S. bank to fail since 2008 after it was seized by regulators and sold to JPMorgan.

ORTHODOX FINANCE MINISTER

Turkey's central bank has had its independence all but stamped out in recent years by Erdogan. A self-proclaimed "enemy" of interest rates, he pressed it to deliver stimulus and was quick to replace governors.

The policy rate was slashed to 8.5% from 19% in 2021, leaving real rates deeply negative and the lira largely managed by dozens of regulations covering credit and foreign exchange.

Yet after Erdogan survived his toughest political test in the May 28 runoff vote, he on Saturday named Mehmet Simsek, a well-respected and orthodox former finance minister, as minister in charge of the economy.

Amid record low foreign reserves of -$5.7 billion, the lira has hit all-time lows this week, plunging 7.2% on Wednesday, and traded at 23.5010 against the dollar after Erkan's appointment.

Analysts said the return of Simsek and the appointment of Erkan set the stage for rate hikes, which could reattract foreign investors after an exodus in recent years.

The apparent U-turn on the economy comes as many analysts anticipate turmoil given depleted foreign reserves, unchecked inflation and wide current account deficits.

The economy's prospects depend on how much independence Erdogan grants Erkan and Simsek, analysts said. In the past, he has embraced orthodoxy, only to quickly double back.

The last central bank governor to raise rates, Naci Agbal, was fired in 2021 after less than five months on the job.

"It is unclear for how long Erdogan may tolerate a more pragmatic stance on the economic front, given the priority he assigns to the March 2024 local elections," said Wolfango Piccoli of Teneo. The ruling AK Party aims to recapture big cities from opposition control in those elections.

Erkan is on Marsh McLennan's board and was named CEO at Greystone, a real estate finance and investment firm, last year.

During her career in New York City, she gained a reputation as "tough, smart, and effective," said Kathryn Wylde, CEO of the Partnership for New York City nonprofit, where Erkan once served as a director.

"She is certainly not someone who can be pushed around, but she also can disagree without being disagreeable," Wylde said.

(Additional reporting by Jonathan Spicer; Editing by Chris Reese and Cynthia Osterman)