The 6'6" guard played in 66 games at VCU, averaging 3.7 points and 2.1 rebounds per game in two seasons with the program.
Gratton's younger brother Dylan remains as a Nittany Lion.
Johnson will reconnect with former Penn State hoops head coach Pat Chambers at Florida Gulf Coast.
Mature at-bats and a united pitching staff pushed Penn State to victory Tuesday night.
With the pair of losses, the Nittany Lions now boast a lowly 2-9 record in the Big Ten.
A massive scoring run in the sixth inning propelled the Nittany Lions to an important win over the Mountaineers.