title: A highly thermostable ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus.
abstract: A ferritin from the obligate anaerobe and hyperthermophilic archaeon Pyrococcus furiosus (optimal growth at 100 degrees C) has been cloned and overproduced in Escherichia coli to one-fourth of total cell-free extract protein, and has been purified in one step to homogeneity. The ferritin (PfFtn) is structurally similar to known bacterial and eukaryal ferritins; it is a 24-mer of 20 kDa subunits, which add up to a total Mr 480 kDa. The protein belongs to the non-heme type of ferritins. The 24-mer contains approximately 17 Fe (as isolated), 2,700 Fe (fully loaded), or <1 Fe (apoprotein). Fe-loaded protein exhibits an EPR spectrum characteristic for superparamagnetic core formation. At 25 degrees C V(max) = 25 micromole core Fe(3+) formed per min per mg protein when measured at 315 nm, and the K(0.5) = 5 mM Fe(II). At 0.3 mM Fe(II) activity increases 100-fold from 25 to 85 degrees C. The wild-type ferritin is detected in P. furiosus grown on starch. PfFtn is extremely thermostable; its activity has a half-life of 48 h at 100 degrees C and 85 min at 120 degrees C. No apparent melting temperature was found up to 120 degrees C. The extreme thermostability of PfFtn has potential value for biotechnological applications.
authors.affiliation: Department of Biotechnology, Delft University of Technology, The Netherlands.
authors.forename: Jana
authors.initials: J
authors.lastname: Tatur
authors.forename: Peter-Leon
authors.initials: PL
authors.lastname: Hagedoorn
authors.forename: Marieke L
authors.initials: ML
authors.lastname: Overeijnder
authors.forename: Wilfred R
authors.initials: WR
authors.lastname: Hagen
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D019843:Archaeal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D005293:Ferritins / Q000737:chemistry* / Q000302:isolation & purification; D006358:Hot Temperature; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D020027:Pyrococcus furiosus / Q000737:chemistry* / Q000235:genetics*; D016415:Sequence Alignment; D013057:Spectrum Analysis
chemical_list: D019843:Archaeal Proteins; D005293:Ferritins