title: Revelation of endogenously bound Fe(2+) ions in the crystal structure of ferritin from Escherichia coli.
abstract: Ferritin is an iron regulatory protein. It is responsible for storage and detoxification of excess iron thereby it regulates iron level in the body. Here we report the crystal structure of ferritin with two endogenously expressed Fe atoms binding in both the sites. The protein was purified and characterized by MALDI-TOF and N-terminal amino acid sequencing. The crystal belongs to I4 space group and it diffracted up to 2.5Å. The structural analysis suggested that it crystallizes as hexamer and confirmed that it happened to be the first report of endogenously expressed Fe ions incorporated in both the A and B sites, situated in between the helices.
authors.affiliation: Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India.
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Thiruselvam
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Padavattan
authors.initials: P
authors.lastname: Sivaraman
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Structural Biology Laboratory, RIKEN Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan. Electronic address: kumarevel.thirumananseri@riken.jp.
authors.forename: Thirumananseri
authors.initials: T
authors.lastname: Kumarevel
authors.affiliation: Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India. Electronic address: mnpsy2004@yahoo.com.
authors.forename: Mondikalipudur Nanjappagounder
authors.initials: MN
authors.lastname: Ponnuswamy
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D005290:Ferric Compounds / Q000378:metabolism*; D005293:Ferritins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D005290:Ferric Compounds; D005293:Ferritins
keywords: Binuclear iron site; Ferritin; Iron regulation