Sensor kinase that senses the plastoquinone (PQ) redox state involved in stoichiometry adjustment of both photosystems (e.g. long-term adaptation via transcriptional regulation of reaction center genes of photosystems I and II) and state transitions (e.g. short-term adaptation involving reversible post-translational phosphorylation of light-harvesting complex II, LHC II), thus linking photosynthesis with gene expression in chloroplasts (PubMed:18632566, PubMed:22039472). Autophosphorylates, probably on a tyrosine residue (PubMed:18632566). Probably phosphorylates SIGA/SIG1 in response to plastoquinone redox state modification (PubMed:23754813). Reduced PQ suppresses its autophosphorylation activity. Represses expression of a number of chloroplast-encoded genes (PubMed:31925322). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] The 3Fe-4S cluster is redox-responsive, binds 1 cluster per monomer. Self-interacts. Interacts with the plastoquinone analog 2,5-dibromo-3-methyl-5-isopropyl-p-benzoquinone (DBMIB) and with SIGA/SIG1. Associates with thylakoid membranes. Autophosphorylated, possibly on tyrosine residues, in photosystem I (PS I) light and in the presence of manganese ions Mn(2+), to a lesser degree, in the presence of calcium ions Ca(2+), but not in the presence of magnesium ions Mg(2+). Dithiothreitol (DTT) stimulates autophosphorylation (PubMed:18632566). Phosphorylated on Ser-188 in vivo after exposure to far-red light (when plastoquinone (PQ) is oxidized). Not phosphorylated under orange light (reduces PQ) (PubMed:31925322). Abnormal regulation of psaA gene expression by light variation and reduced plastoquinone (PQ) pool (PubMed:18632566, PubMed:22039472). Accentuated superimposition effect of light leading to PQ oxidation. Increased level of non-photochemical quenching, faster pre-steady state kinetics of the 'Kautsky' transient (PubMed:22039472). Up-regulation of chloroplast-encoded photosystem and non-photosystem genes (PubMed:31925322). Belongs to the chloroplast sensor kinase protein family. Truncated N-terminus.