Cyanobacterial protein with similarity to the chlorophyll a/b binding proteins of higher plants: evolution and regulation.

We have isolated, from the prokaryotic cyanobacterium Synechococcus sp. strain PCC 7942, a gene encoding a protein of 72 amino acids [designated high light inducible protein (HLIP)] with similarity to the extended family of eukaryotic chlorophyll a/b binding proteins (CABs). HLIP has a single membrane-spanning alpha-helix, whereas both the CABs and the related early light inducible proteins have three membrane-spanning helices. Hence, HLIP may represent an evolutionary progenitor of the eukaryotic members of the CAB extended family. We also show that the gene encoding HLIP is induced by high light and blue/UV-A radiation. The evolution, regulation, and potential function of HLIP are discussed.