Ferritin from the obligate anaerobe Porphyromonas gingivalis: purification, gene cloning and mutant studies.
Porphyromonas gingivalis is an obligate anaerobe that utilizes haem, transferrin and haemoglobin efficiently as sources of iron for growth, and has the ability to store haem on its cell surface, resulting in black pigmentation of colonies on blood agar plates. However, little is known about intracellular iron storage in this organism. Ferritin is one of the intracellular iron-storage proteins and may also contribute to the protection of organisms against oxidative stresses generated by intracellular free iron. A ferritin-like protein was purified from P. gingivalis and the encoding gene (ftn) was cloned from chromosomal DNA using information on its amino-terminal amino acid sequence. Comparison of the amino acid sequence deduced from the nucleotide sequence of ftn with those of known ferritins and bacterioferritins identified the protein as a ferritin and positioned it between proteins from the Proteobacteria and Thermotogales. The P. gingivalis ferritin was found to contain non-haem iron, thus confirming its identity. Construction and characterization of a P. gingivalis ferritin-deficient mutant revealed that the ferritin was particularly important for the bacterium to survive under iron-depleted conditions (both haemin and transferrin starvation), indicating that intracellular iron is stored in ferritin regardless of the iron source and that the iron stored in ferritin is utilized under iron-restricted conditions. However, the ferritin appeared not to contribute to protection against oxidative stresses caused by peroxides and atmospheric oxygen.
Ratnayake
Dinath B
DB
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
Wai
Sun Nyunt
SN
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
Shi
Yixin
Y
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
Amako
Kazunobu
K
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
Nakayama
Hiroaki
H
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
Nakayama
Koji
K
Department of Microbiology, Faculty of Dentistry1 and Department of Bacteriology, Faculty of Medicine2, Kyushu University, Fukuoka 812-8582, Japan.
D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D018274:Electroporation; D004926:Escherichia coli; D005293:Ferritins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial; D006427:Hemin; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016966:Porphyromonas gingivalis / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D011994:Recombinant Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D014168:Transferrin; D014462:Ultrafiltration
D003470:Culture Media; D011994:Recombinant Proteins; D014168:Transferrin; D006427:Hemin; D005293:Ferritins