While, for Conan O’Brien, being moved to midnight amounted to the last straw, for ABC’s Jimmy Kimmel, it’s a step up.

ABC announced Thursday that the start time for “Jimmy Kimmel Live” would move five minutes earlier, to midnight, beginning Feb. 3, a Thursday marking the start of the next rating sweeps. That means lead-in “Nightline” will be reduced from a half-hour to 25 minutes.

Sources say securing an earlier start was part of Kimmel’s latest contract renewal with the network.

In his memo to staff, new ABC News prexy Ben Sherwood stressed the lost time wouldn’t impact “Nightline,” which — despite solid ratings — has long been con-sidered vulnerable to the whims of ABC’s entertainment division. Part of that dates back to the network’s failed bid to land David Letterman, which preceded Ted Koppel’s departure.

Sherwood noted in the memo that “Nightline” would be producing 13 hours of primetime programming for ABC in the coming year — over and above what ABC News does with “20/20” and specials — which Sherwood called “a serious boon to the division.” The programs will be titled “Nightline Prime.”

After significant layoffs in 2010, ABC News has been somewhat uneasy despite Sherwood’s assurances that there are no plans for further cuts. During the recent TV Critics Assn. tour, the exec also cited plans to work more closely with the entertainment division.

Under its current format, “Nightline” features multiple segments in each half-hour and usually closes each show with a lighter look at the news. The major networks moved years ago to the 11:35 p.m. end time for local news, providing ABC stations a few extra minutes of local ad time to sell.