Kate Purchase, the executive director of communications and planning in the Prime Minister's Office, will be leaving her post at the end of the week following more than six years as a senior adviser to Justin Trudeau.

Purchase announced her departure in a note to staff on Tuesday, adding to the turnover that Trudeau's senior team has experienced over the past year. She will be moving to a position with tech giant Microsoft.

Purchase was director of media relations to interim Liberal leader Bob Rae in 2013 when Trudeau was elected leader of the Liberal Party. She was persuaded to stay on with the new leader and became one of a group of advisers who remained with Trudeau throughout his first term as prime minister and this fall's re-election campaign.

In her current role, she oversaw the government's communications and Trudeau's public events and official travel.

While the senior figures in Stephen Harper's PMO tended to change on a regular basis — Harper had four chiefs of staff and nine directors of communication during his time in office — the team around Trudeau has been relatively stable. The first real wave of significant turnover has come as Trudeau begins his second term with a minority government.

Gerry Butts, a close friend to Trudeau, returned to the prime minister's side for the federal campaign, but he did not resume his role as principal secretary in the PMO after the election — a position he resigned last spring in the midst of the SNC-Lavalin affair.

Gerry Butts during a visit to the Great Wall of China in Beijing September 1, 2016. (Adrian Wyld/Canadian Press)

Butts, who has known Trudeau since they were both students at McGill University, was the first person Trudeau turned to when Trudeau began mulling a run for the Liberal leadership in 2012.

Two weeks ago, Mike McNair, the executive director of policy in the PMO, announced that he would depart at the end of the year. McNair was a member of Trudeau's leadership campaign and went on to play a significant role in designing Trudeau's "middle class" agenda, including the Canada Child Benefit.

Despite that turnover, Trudeau is not surrounded entirely by unfamiliar faces. Katie Telford remains as Trudeau's chief of staff. She has been one of Trudeau's closest advisers since the beginning and her tenure as the top official in the PMO now rivals those of some of the longest-serving aides in the history of the office.

Ben Chin, previously chief of staff to Finance Minister Bill Morneau and briefly a member of Trudeau's leadership campaign, joined the PMO as a senior adviser in the wake of Butts' depature. And McNair has been replaced by Marci Surkes, who worked in Trudeau's office before 2015 and was then chief of staff to Ralph Goodale when Goodale was public safety minister.