Analysis of conserved glutamate residues in Porphyromonas gingivalis outer membrane receptor HmuR: toward a further understanding of heme uptake.
The aim of this study was to broaden the current knowledge about the Porphyromonas gingivalis heme receptor HmuR. Site-directed mutagenesis was employed to replace Glu427, Glu448, Glu458 and Glu503 by alanines and to construct a triple Glu427Ala/Glu448Ala/Glu 458Ala mutant. All iron/heme-starved P. gingivalis mutants showed decreased growth recovery when human serum as the iron/heme source was used, hmuR::ermF, hmuR (E503A) and hmuR (E427A,E448A,E458A) mutant strains being the most affected. E. coli cells expressing HmuR with mutated glutamate residues bound hemin, hemoglobin and hemin-serum albumin complex with the same efficiency as did the wild-type recombinant protein, suggesting that the residues were not directly involved in heme binding. These data indicate that in addition to two conserved histidine residues (His95 and His434), NPDL and YRAP motifs, conserved glutamate residues are important for HmuR to utilize heme present in serum hemoproteins.
Olczak
Teresa
T
Laboratory of Biochemistry, Institute of Biochemistry and Molecular Biology, Wroclaw University, Tamka 2, 50-137 Wroclaw, Poland. Teresa.Olczak@bf.uni.wroc.pl
D000418:Albumins / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D018698:Glutamic Acid / Q000502:physiology*; D006418:Heme / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010518:Periodontitis / Q000382:microbiology; D017354:Point Mutation; D016966:Porphyromonas gingivalis / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014774:Virulence
D000418:Albumins; D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D006454:Hemoglobins; D011956:Receptors, Cell Surface; C028027:heme receptor; D018698:Glutamic Acid; D006418:Heme