A highly thermostable ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus.
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.
Tatur
Jana
J
Department of Biotechnology, Delft University of Technology, The Netherlands.
Hagedoorn
Peter-Leon
PL
Overeijnder
Marieke L
ML
Hagen
Wilfred R
WR
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
D019843:Archaeal Proteins; D005293:Ferritins