title: Chlorophyll biosynthesis in bacteria: the origins of structural and functional diversity.
abstract: The use of photochemical reaction centers to convert light energy into chemical energy, chlorophototrophy, occurs in organisms belonging to only five eubacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, and Firmicutes. All chlorophototrophs synthesize two types of pigments: (a) chlorophylls and bacteriochlorophylls, which function in both light harvesting and uniquely in photochemistry; and (b) carotenoids, which function primarily as photoprotective pigments but can also participate in light harvesting. Although hundreds of carotenoids have been identified, only 12 types of chlorophylls (Chl a, b, d; divinyl-Chl a and b; and 8(1)-hydroxy-Chl a) and bacteriochlorophylls (BChl a, b, c, d, e, and g) are currently known to occur in bacteria. This review summarizes recent progress in the identification of genes and enzymes in the biosynthetic pathways leading to Chls and BChls, the essential tetrapyrrole cofactors of photosynthesis, and addresses the mechanisms for generating functional diversity for solar energy capture and conversion in chlorophototrophs.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. aug111@psu.edu
authors.forename: Aline Gomez Maqueo
authors.initials: AG
authors.lastname: Chew
authors.forename: Donald A
authors.initials: DA
authors.lastname: Bryant
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism*; D001429:Bacteriochlorophylls / Q000096:biosynthesis* / Q000737:chemistry; D002735:Chlorophyllides / Q000096:biosynthesis; D011524:Protoporphyrins / Q000378:metabolism
chemical_list: D001429:Bacteriochlorophylls; D002735:Chlorophyllides; D011524:Protoporphyrins; C034388:chlorophyllide a; C028025:protoporphyrin IX