Catalyzes the phosphorylation of autoinducer-2 (AI-2) to phospho-AI-2, which subsequently inactivates the transcriptional regulator LsrR and leads to the transcription of the lsr operon. Phosphorylates the ring-open form of (S)-4,5-dihydroxypentane-2,3-dione (DPD), which is the precursor to all AI-2 signaling molecules, at the C5 position. Required for the regulation of the lsr operon and many other genes. (S)-4,5-dihydroxypentane-2,3-dione + ATP = (2S)-2-hydroxy-3,4-dioxopentyl phosphate + ADP + H(+) Belongs to the FGGY kinase family. Was originally thought to originate from human and was called BRAG1 (brain-related apoptosis gene 1) with a proposed role in apoptosis (PubMed:8649811). The DNA sequence of the region sequenced is more than 99% identical to that of this E.coli gene. Furthermore the claim of an 'extensive similarity to the Bcl-2 family of genes' is not correct.