title: Phylloquinone (Vitamin K1): Occurrence, Biosynthesis and Functions.
abstract: BACKGROUND
  Phylloquinone is a prenylated naphthoquinone that is synthesized exclusively by plants, green algae, and some species of cyanobacteria, where it serves as a vital electron carrier in photosystem I and as an electron acceptor for the formation of protein disulfide bonds.
  
  
  OBJECTIVE
  In humans and other vertebrates, phylloquinone plays the role of a vitamin (vitamin K1) that is required for blood coagulation and bone and vascular metabolism. Phylloquinone from green leafy vegetables and vegetable oil represents the major dietary source of vitamin K for humans.
  
  
  METHODS
  In recent years, reverse genetics and biochemical approaches using the model plant Arabidopsis thaliana have shown that phylloquinone biosynthesis in plants involves paralogous and multifunctional enzymes, a compartmentation of the corresponding pathway in plastids and peroxisomes, and trafficking of some biosynthetic intermediates within plastids themselves. Furthermore, phylloquinone biosynthetic intermediates create crucial metabolic branch-points with other plastid-synthesized metabolites such as chlorophylls, tocopherols and salicylate.
  
  
  CONCLUSIONS
  This review presents an update on recent studies of the central role of plastids in the biosynthesis of phylloquinone, in particular on the discovery of novel enzymatic steps that are likely paradigms for phylloquinone and menaquinone (vitamin K2)-synthesizing organisms alike.
authors.affiliation: Horticultural Sciences Department, University of Florida, Gainesville, FL 32608, United States.
authors.forename: Gilles J
authors.initials: GJ
authors.lastname: Basset
authors.affiliation: Horticultural Sciences Department, University of Florida, Gainesville, FL 32608, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Latimer
authors.affiliation: Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, Versailles, France.
authors.forename: Abdelhak
authors.initials: A
authors.lastname: Fatihi
authors.affiliation: Horticultural Sciences Department, University of Florida, Gainesville, FL 32608, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Soubeyrand
authors.affiliation: Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, US Department of Agriculture; 1600 SW 23rd Drive Gainesville FL 32608, United States.
authors.forename: Anna
authors.initials: A
authors.lastname: Block
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000378:metabolism; D001777:Blood Coagulation / Q000187:drug effects; D002736:Chloroplasts / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003374:Coumarins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000458:Cyanobacteria / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D010944:Plants / Q000737:chemistry / Q000378:metabolism; D010837:Vitamin K 1 / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D003374:Coumarins; D010837:Vitamin K 1
keywords: Phylloquinone; chloroplasts; naphthoquinones; peroxisomes; photosynthesis; plastoglobules; vitamin K