Serine/threonine kinase that modulates host metabolism to favor virus replication cycle. Participates together with gene 2 protein (gp2) in the host transcription shutoff. Phosphorylates host RNA polymerase subunit RpoC and to a lesser extent subunit RpoB. This modification seems to increase rho-dependent transcription termination, which may help to switch from host to viral RNA polymerase transcription during phage development. Phosphorylates host components of the RNA degradosome rne and RhlB, leading to stabilization of mRNAs synthesized by T7 RNA polymerase. Phosphorylates host dsRNA specific processing enzyme RNase III/rnc, leading to enhance activity of the ribonuclease that may increase maturation of T7 late transcripts possessing multiple Rnase III processing sites. Phosphorylates several components of the host translational machinery including initiation factors InfA, InfB, and InfC, ribosomal subunit RpsA and RpsF, as well as elongation factor G/FusA. These phosphorylations may enhance T7 late protein production. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein]