L-threonylcarbamoyl-AMP synthase, biosynthesis of the hypermodified base threonylcarbamoyladenosine (t(6)A) (together with [[protein|6CB350C335603D5F4434679F9D740BFECA738599]]-[[protein|30393F16CFE89E7BAD233A0BD27B77D679F7E409]]-[[protein|E15BB518649B2B9CD44CEBBB4FA481E55BCE823C]])