title: A family of GFP-like proteins with different spectral properties in lancelet Branchiostoma floridae.
abstract: BACKGROUND
  Members of the green fluorescent protein (GFP) family share sequence similarity and the 11-stranded beta-barrel fold. Fluorescence or bright coloration, observed in many members of this family, is enabled by the intrinsic properties of the polypeptide chain itself, without the requirement for cofactors. Amino acid sequence of fluorescent proteins can be altered by genetic engineering to produce variants with different spectral properties, suitable for direct visualization of molecular and cellular processes. Naturally occurring GFP-like proteins include fluorescent proteins from cnidarians of the Hydrozoa and Anthozoa classes, and from copepods of the Pontellidae family, as well as non-fluorescent proteins from Anthozoa. Recently, an mRNA encoding a fluorescent GFP-like protein AmphiGFP, related to GFP from Pontellidae, has been isolated from the lancelet Branchiostoma floridae, a cephalochordate (Deheyn et al., Biol Bull, 2007 213:95).
  
  
  RESULTS
  We report that the nearly-completely sequenced genome of Branchiostoma floridae encodes at least 12 GFP-like proteins. The evidence for expression of six of these genes can be found in the EST databases. Phylogenetic analysis suggests that a gene encoding a GFP-like protein was present in the common ancestor of Cnidaria and Bilateria. We synthesized and expressed two of the lancelet GFP-like proteins in mammalian cells and in bacteria. One protein, which we called LanFP1, exhibits bright green fluorescence in both systems. The other protein, LanFP2, is identical to AmphiGFP in amino acid sequence and is moderately fluorescent. Live imaging of the adult animals revealed bright green fluorescence at the anterior end and in the basal region of the oral cirri, as well as weaker green signals throughout the body of the animal. In addition, red fluorescence was observed in oral cirri, extending to the tips.
  
  
  CONCLUSIONS
  GFP-like proteins may have been present in the primitive Metazoa. Their evolutionary history includes losses in several metazoan lineages and expansion in cephalochordates that resulted in the largest repertoire of GFP-like proteins known thus far in a single organism. Lancelet expresses several of its GFP-like proteins, which appear to have distinct spectral properties and perhaps diverse functions.
  
  
  METHODS
  This article was reviewed by Shamil Sunyaev, Mikhail Matz (nominated by I. King Jordan) and L. Aravind.
authors.affiliation: Stowers Institute for Medical Research, 1000 E 50th St,, Kansas City, MO 64110, USA. dpb@stowers-institute.org
authors.forename: Diana
authors.initials: D
authors.lastname: Baumann
authors.forename: Malcolm
authors.initials: M
authors.lastname: Cook
authors.forename: Limei
authors.initials: L
authors.lastname: Ma
authors.forename: Arcady
authors.initials: A
authors.lastname: Mushegian
authors.forename: Erik
authors.initials: E
authors.lastname: Sanders
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: C Ron
authors.initials: CR
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002816:Chordata, Nonvertebrate / Q000737:chemistry* / Q000235:genetics; D017124:Conserved Sequence; D019143:Evolution, Molecular; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D005810:Multigene Family; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D040681:Structural Homology, Protein
chemical_list: D049452:Green Fluorescent Proteins