After three years in the position, Clark Atlanta University’s president is resigning. The university says it is immediately beginning a national search for its fifth president.

Ronald A. Johnson has been president since July 2015.

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A university news release says Chief Operating Officer Lucille Maugé will be acting president after Johnson leaves Dec. 7.

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The Atlanta Journal-Constitution quotes a letter from Johnson as saying he’s leaving for personal reasons.

Gregory Morrison is chair of the university’s Board of Trustees. He says Johnson has made many contributions, which include improving the academic quality of admitted students and developing a new strategic plan.

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Johnson came to Clark Atlanta from Texas Southern University, where he was dean of the business school.