I am flying to Nepal via Turkish Airlines next month. My itinerary also has just one hour transit period at Istanbul Airport. I bought it from Cheapoair. So I just called them to make sure about it. The agent told me that one hour is enough to catch the next flight otherwise they would not even issue the ticket like this. And in case, that next flight is missed because of the airlines, then it will be the full responsibility of Turkish Airlines and they will take care of everything. Hope this helps you guys.