MacKay, a soulful mezzo-soprano who provided backing vocals on such 1960s classics as “Suspicious Minds” and “When a Man Loves a Woman” and was a featured singer with the Grateful Dead for much of the 1970s,

Donna Jean Godchaux-MacKay, a singer who performed on hits such as “When a Man Loves a Woman” by Percy Sledge and helped shape the sound of the Grateful Dead in the 1970s, died on Sunday in Nashville.