title: The structure of mAG, a monomeric mutant of the green fluorescent protein Azami-Green, reveals the structural basis of its stable green emission.
abstract: Monomeric Azami-Green (mAG) from the stony coral Galaxea fascicularis is the first known monomeric green-emitting fluorescent protein that is not a variant of Aequorea victoria green fluorescent protein (avGFP). These two green fluorescent proteins are only 27% identical in their amino-acid sequences. mAG is more similar in its amino-acid sequence to four fluorescent proteins: Dendra2 (a green-to-red irreversibly photoconverting fluorescent protein), Dronpa (a bright-and-dark reversibly photoswitchable fluorescent protein), KikG (a tetrameric green-emitting fluorescent protein) and Kaede (another green-to-red irreversibly photoconverting fluorescent protein). To reveal the structural basis of stable green emission by mAG, the 2.2 A crystal structure of mAG has been determined and compared with the crystal structures of avGFP, Dronpa, Dendra2, Kaede and KikG. The structural comparison revealed that the chromophore formed by Gln62-Tyr63-Gly64 (QYG) and the fixing of the conformation of the imidazole ring of His193 by hydrogen bonds and van der Waals contacts involving His193, Arg66 and Thr69 are likely to be required for the stable green emission of mAG. The crystal structure of mAG will contribute to the design and development of new monomeric fluorescent proteins with faster maturation, brighter fluorescence, improved photostability, new colours and other preferable properties as alternatives to avGFP and its variants.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Ebisawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yamamura
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kameda
authors.forename: Kou
authors.initials: K
authors.lastname: Hayakawa
authors.forename: Koji
authors.initials: K
authors.lastname: Nagata
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanokura
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D003116:Color; D018360:Crystallography, X-Ray; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D049452:Green Fluorescent Proteins
references.citation: J Mol Biol. 2007 Sep 28;372(4):918-926
references.pmid: 17692334
references.citation: Acta Crystallogr D Biol Crystallogr. 2000 Dec;56(Pt 12):1622-4
references.pmid: 11092928
references.citation: Bioinformatics. 2000 Jun;16(6):566-7
references.pmid: 10980157
references.citation: J Biol Chem. 2003 Sep 5;278(36):34167-71
references.pmid: 12819206
references.citation: Acta Crystallogr D Biol Crystallogr. 1993 Jan 1;49(Pt 1):129-47
references.pmid: 15299554
references.citation: Biochemistry. 2009 Jun 9;48(22):4905-15
references.pmid: 19371086
references.citation: Nat Rev Mol Cell Biol. 2002 Dec;3(12):906-18
references.pmid: 12461557
references.citation: EMBO Rep. 2005 Mar;6(3):233-8
references.pmid: 15731765
references.citation: Proc Natl Acad Sci U S A. 2001 Aug 28;98(18):10037-41
references.pmid: 11517324
references.citation: Annu Rev Biochem. 1998;67:509-44
references.pmid: 9759496
references.citation: Biochem J. 2007 Feb 15;402(1):35-42
references.pmid: 17117927
references.citation: Acta Crystallogr Sect F Struct Biol Cryst Commun. 2009 Dec 1;65(Pt 12):1292-5
references.pmid: 20054132
references.citation: J Mol Biol. 1990 Oct 5;215(3):403-10
references.pmid: 2231712
references.citation: Appl Microbiol Biotechnol. 2007 Nov;77(1):1-12
references.pmid: 17704916
references.citation: Science. 1996 Sep 6;273(5280):1392-5
references.pmid: 8703075
references.citation: Methods Biochem Anal. 2006;47:1-13
references.pmid: 16335707
references.citation: Acta Crystallogr D Biol Crystallogr. 1997 May 1;53(Pt 3):240-55
references.pmid: 15299926
references.citation: Nucleic Acids Res. 2007 Jul;35(Web Server issue):W375-83
references.pmid: 17452350
references.citation: Nat Biotechnol. 1996 Oct;14(10):1246-51
references.pmid: 9631087
references.citation: Proc Natl Acad Sci U S A. 2007 Aug 7;104(32):13005-9
references.pmid: 17646653
references.citation: Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 1):2126-32
references.pmid: 15572765