Johnson, 19, has yet to even make his senior debut but will move to Castleford’s Super League rivals immediately on a four-year deal.
Although it is the second talented Tigers youngster to leave in as many weeks after England Academy stand-off Callum McLelland switched codes with Edinburgh, the club is delighted to see Trueman stay.
The scrum-half, who scored a sensational quickfire hat-trick on his first Super League start at Wigan in September, has signed a new three-year contract that will keep him at the Tigers until the end of 2020.
That is a major fillip for the League Leaders’ Shield winners although it is the news of Warrington’s eagerness to sign Johnson that has taken plenty by surprise.
Castleford head coach Daryl Powell explained: “We were recently approached by Warrington Wolves with an incredible offer for a young player and after taking a long time to consider their offer we decided to allow Luis Johnson to move to Warrington immediately.
“We have taken into account Luis’ wish to take up this offer and our significant depth and length of contract in the back-row and felt it was best in both Luis’ and our clubs interests, that we allowed him to further his career at the Wolves.
“Having made a conscious decision where our positional priorities lie with young players, we will now focus on developing our talent where we need it the most. I’d like to wish Luis all the best in the future for his career.”
Johnson was named Player of the Series in England Academy’s recent Test success over France.
England academy’s coach is Lee Briers, the Warrington assistant, and Wolves head coach Steve Price said: “Luis is a great young talent who is held in high regard in the English rugby league community.
“We were attracted by his powerful attacking skills and strong, aggressive defence.
“Lee Briers speaks highly of him, naming him as his stand-out player in the series against France, where his passion for the game and willingness to learn shone through.
“We look forward to watching him develop over the coming years. Luis will be a great addition to the squad.”
Trueman, meanwhile, joined Castleford at the start of the year from Bradford Bulls after they hit financial trouble.
Powell said: “I’m really happy that Jake has decided to extend his stay with us.
“He’s shown, in particular, against Wigan, that he has a tonne of potential.
“He is a mature rugby league player for his age and we think there is a lot more to come from him.
“I think he is the most promising half back in the English game.”