Both Nobel laureate Desmond Tutu and Graca Machel, an activist and widow of Nelson Mandela, have been feted in the name of Muslim cleric Fethullah Gulen, who has won international recognition for promoting dialogue and education. [...] this year's award ceremony is in doubt as Turkey campaigns globally to shut schools and other institutes linked to Gulen, who once enjoyed support from the Turkish government that now calls him a terrorist. The Turkish bid is complicated by questions of national sovereignty and whether there is evidence of links between far-flung projects — many with no formal ties to Gulen's headquarters in the U.S.