I have a line with thousands of lines like this:

 {"100K";"0.00001";"10";"0.01"]}
 {"101K";"0.0001";"100";"0.1"]}
 {"102K";"1";"1000";"1"]}
 {"102K";"1";"1000";"1"]}
 {"103K";"0.01";"10000";"10"]}
 {"104K";"0.1";"100000";"100"]}
 {"105K";"1";"1000000";"1000"]}
 {"109K";"0.000001";"1";"1"]}
 {"120K";"0.000012";"12";"12"]}

I want to replace the first occurrence of `;` in a line with `:[`

Making these lines equal to

 {"100K":["0.00001";"10";"0.01"]}
 {"101K":["0.0001";"100";"0.1"]}
 {"102K":["1";"1000";"1"]}
 {"102K":["1";"1000";"1"]}
 {"103K":["0.01";"10000";"10"]}
 {"104K":["0.1";"100000";"100"]}
 {"105K":["1";"1000000";"1000"]}
 {"109K":["0.000001";"1";"1"]}
 {"120K":["0.000012";"12";"12"]}

how do I do that with sed or other unix command?