, Volume 17, Issue 3, pp 209–216

Lactoferrin and Iron: structural and dynamic aspects of binding and release



Lactoferrin (Lf) has long been recognized as a member of the transferrin family of proteins and an important regulator of the levels of free iron in the body fluids of mammals. Its ability to bind ferric iron with high affinity (KD∼10−20 M) and to retain it to low pH gives the protein bacteriostatic and antioxidant properties. This ability can be well understood in terms of its three dimensional (3D) structure. The molecule is folded into two homologous lobes (N- and C-lobes) with each lobe binding a single Fe3+ ion in a deep cleft between two domains. The iron sites are highly conserved, and highly favorable for iron binding. Iron binding and release are associated with large conformational changes in which the protein adopts either open or closed states. Comparison of available apolactoferrin structures suggests that iron binding is dependent on the dynamics of the open state. What triggers release of the tightly bound iron, however, and why lactoferrin retains iron to much lower pH than its serum homologue, transferrin, has been the subject of much speculation. Comparisons of structural and functional data on lactoferrins and transferrins now suggest that the key factor comes from cooperative interactions between the two lobes of the molecule, mediated by two α-helices.


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  1. Aisen P, Harris DC. 1989 Physical biochemistry of the transferrins. In: Loehr T, ed. Iron Carriers and Iron Proteins, Vol 5. New York: VCH Publishers: 241-251.Google Scholar
  2. Anderson BF, Baker HM, Dodson EJ, Norris GE, Rumball SV, Waters JM, Baker EN. 1987 The structure of human lactoferrin at 3.2 Å resolution. Proc Natl Acad Sci USA 84, 1769-1773.PubMedGoogle Scholar
  3. Anderson BF, Baker HM, Norris GE, Rice DW, Baker EN. 1989 Structure of human lactoferrin: Structure analysis and refinement at 2.8 Å resolution. J Mol Biol 209, 711-734.PubMedGoogle Scholar
  4. Anderson BF, Baker HM, Norris GE, Rumball SV, Baker EN. 1990 Apolactoferrin structure demonstrates ligand-induced conformational change in transferrins. Nature 344, 784-787.PubMedGoogle Scholar
  5. Bailey S, Evans RW, Garratt RC, Gorinsky B, Hasnain S, Horsburgh C, Jhoti H, Lindley PF, Mydin A, Sarra R, Watson JL. 1988 Molecular structure of serum transferrin at 3.3 Å resolution. Biochemistry 27, 5804-5812.PubMedGoogle Scholar
  6. Baker EN. 1994 Structure and reactivity of transferrins. Adv Inorg Chem 41, 389-463.Google Scholar
  7. Baker EN and Lindley PF. 1992 New perspectives on the structure and function of transferrins. J Inorg Biochem 47, 147-160.PubMedGoogle Scholar
  8. Baker EN, Rumball SV, Anderson BF. 1987 Transferrins: Insights into structure and function from studies on lactoferrin. Trends Biochem Sci 12, 350-353.Google Scholar
  9. Baker EN, Anderson BF, Baker HM, Faber HR, Smith CA, Sutherland-Smith AJ. 1997 In: Hutchens TW, Lonnerdal B, eds. Lactoferrin: Interactions and Biological Functions. Totowa NJ: Humana Press, 177-191.Google Scholar
  10. Baker EN, Baker HM, Kidd, RD. 2002 Lactoferrin and transferrin: Functional variations on a common structural framework. Biochem Cell Biol 80, 27-34.PubMedGoogle Scholar
  11. Baker HM, He Q-Y, Briggs SK, Mason AB, Baker EN. 2003 Structural and functional consequences of binding site mutations in transferrin: Crystal structures of the Asp63Glu and Arg124Ala mutants of the N-lobe of human transferrin. Biochemistry 42, 7084-7089.PubMedGoogle Scholar
  12. Baldwin DA, Jenny RR, Aisen P. 1984 The effect of human serum transferrin and milk lactoferrin on hydroxyl radical formation from superoxide and hydrogen peroxide. J Biol Chem 259, 13391-13394.PubMedGoogle Scholar
  13. Bali PK, Aisen P. 1991 Receptor-modulated iron release from transferrin: Differential effects on the N-and C-terminal sites. Biochemistry 30, 9947-9952.PubMedGoogle Scholar
  14. Bellamy W, Takase M, Yamauchi K, Wakabayashi H, Kawase K, Tomita M. 1992 Identification of the bactericidal domain of lactoferrin. Biochim Biophys Acta 1121, 130-136.PubMedGoogle Scholar
  15. Bennett RM, Davis J. 1982 Lactoferrin interacts with deoxyribonucleic acid: A preferential reactivity with double-stranded DNA and dissociation of DNA-anti-DNA complexes. J Lab Clin Med 99, 127-138.PubMedGoogle Scholar
  16. Bruns CM, Nowalk AJ, Arvai AS, McTigue MA, Vaughan KG, Mietzner TA, McRee DE. 1997 Structure of Haemophilus influenzae Fe+3-binding protein reveals convergent evolution within a superfamily. Nature Struct Biol 4, 919-924.PubMedGoogle Scholar
  17. Bullen JJ, Rogers HJ, Leigh L. 1972 Iron-binding proteins in milk and resistance to Escherichia coli infections in infants. Brit Med J 1, 69-75.PubMedGoogle Scholar
  18. Day CL, Stowell KM, Baker EN, Tweedie JW. 1992 Studies of the N-terminal half of lactoferrin produced from the cloned cDNA demonstrate that interlobe interactions modulate iron release. J Biol Chem 267, 13857-13862.PubMedGoogle Scholar
  19. Dewan JC, Mikami B, Hirose M, Sacchettini JC. 1993 Structural evidence for a pH-sensitive dilysine trigger in the hen ovotransferrin N-lobe: Implications for transferrin iron release. Biochemistry 32, 11963-11968.PubMedGoogle Scholar
  20. El Hage Chahine J-M, Pakdaman R. 1995. Transferrin, a mechanism for iron release. Eur J Biochem 230, 1102-1110.PubMedGoogle Scholar
  21. Faber HR, Bland T, Day CL, Norris GE, Tweedie JW, Baker EN. 1996 Altered domain closure and iron-binding in transferrins: The crystal structure of the Asp60Ser mutant of the amino-terminal half-molecule of human lactoferrin. J Mol Biol 256, 352-363.PubMedGoogle Scholar
  22. Grossmann JG, Neu M, Pantos E, Schwab FJ, Evans RW, Towns-Andrews E, Lindley PF, Appel H, Thies W-G, Hasnain SS. 1992 X-ray solution scattering reveals conformational changes upon iron uptake in lactoferrin, serum and ovotransferrins. J Mol Biol 225, 811-819.PubMedGoogle Scholar
  23. Groves ML. 1960 The isolation of a red protein from milk. J Am Chem Soc 82, 3345-3350.Google Scholar
  24. Haridas M, Anderson BF, Baker EN. 1995 Structure of human diferric lactoferrin, refined at 2.2 Å resolution. Acta Cryst D51, 629-646.Google Scholar
  25. He J, Furmanski P. 1995 Sequence specificity and transcriptional activation in the binding of lactoferrin to DNA. Nature 373, 721-724.PubMedGoogle Scholar
  26. Jameson GB, Anderson BF, Norris GE, Thomas DH, Baker EN. 1998 Structure of human apolactoferrin at 2.0 Å resolution. Refinement and analysis of ligand-induced conformational change. Acta Cryst D54, 1319-1335.Google Scholar
  27. Jeffrey PD, Bewley MC, MacGillivray RTA, Mason AB, Woodworth RC, Baker EN. 1998 Ligand-induced conformational change in transferrins: Crystal structure of the open form of the N-terminal half-molecule of human transferrin. Biochemistry 40, 13978-13986.Google Scholar
  28. Johansson B. 1960 Isolation of an iron-containing red protein from human milk. Acta Chem Scand 14, 510-512.Google Scholar
  29. Karthikeyan S, Paramasivam M, Yadav S, Srinivasan A, Singh TP. 1999 Structure of buffalo lactoferrin at 2.5 Å resolution using crystals grown at 303K shows different orientations of the N and C lobes. Acta Cryst D55, 1805-1813.Google Scholar
  30. Khan JA, Kumar P, Paramasivam M, Yadav RS, Sahani MS, Sharma S, Srinivasan A, Singh TP. 2001a Camel lactoferrin, a transferrincum-lactoferrin: Crystal structure of camel lactoferrin at 2.6 Å resolution and structural basis of its dual role. J Mol Biol 309, 751-761.PubMedGoogle Scholar
  31. Khan JA, Kumar P, Srinivasan A, Singh TP. 2001b Protein intermediate trapped by the simultaneous crystallization process. J Biol Chem 276, 36817-36823.PubMedGoogle Scholar
  32. Kraulis PJ. 1991 MOLSCRIPT: a program to produce both detailed and schematic plots of protein structures. J Appl Cryst 24, 946-950.Google Scholar
  33. Kurokawa H, Mikami B, Hirose M. 1995 Crystal structure of diferric hen ovotransferrin at 2.4 Å resolution. J Mol Biol 254, 196-207.PubMedGoogle Scholar
  34. Kurokawa H, Dewan JC, Mikami B, Sacchettini JC, Hirose M. 1999 Crystal structure of hen apo-ovotransferrin at 2.4 Å resolution. J Mol Biol 254, 196-207.Google Scholar
  35. MacGillivray RTA, Moore SA, Chen J, Anderson BF, Baker H, Luo Y, Bewley M, Smith CA, Murphy MEP, Wang Y, Mason AB, Woodworth RC, Brayer GD, Baker EN. 1998 Two high resolution structures of the recombinant N-lobe of human transferrin reveal a structural change implicated in iron release. Biochemistry 37, 7919-7928.PubMedGoogle Scholar
  36. Mann DM, Romm E, Migliorini M. 1994 Delineation of a glycosaminoglycan-binding site in the human inflammatory response protein lactoferrin. J Biol Chem 269, 23661-23667.PubMedGoogle Scholar
  37. Mazurier J, Spik G. 1980 Comparative study of the iron-binding properties of human transferrins. Biochim Biophys Acta 629, 399-408.PubMedGoogle Scholar
  38. Merritt EA, Bacon DJ. 1997 Raster3D: photorealistic molecular graphics. Methods Enzymol 277, 505-524.Google Scholar
  39. Metz-Boutigue M-H, Jolles J, Mazurier J, Schoentgen F, Legrand D, Spik G, Montreuil J, Jolles P. 1984 Human lactotransferrin: Amino acid sequence and structural comparisons with other transferrins. Eur J Biochem 145, 659-676.PubMedGoogle Scholar
  40. Montreuil J, Tonnelat J, Mullet S. 1960 Preparation et proprietes de la lactosiderophiline (lactotransferrine) du lait du femme. Biochim Biophys Acta 45, 413-421.PubMedGoogle Scholar
  41. Moore SA, Anderson BF, Groom CR, Haridas M, Baker EN. 1998 Three-dimensional Structure of diferric bovine lactoferrin at 2.8 Å resolution. J Mol Biol 274, 222-236.Google Scholar
  42. Nicholson H, Anderson BF, Bland T, Shewry SC, Tweedie JW, Baker EN. 1997 Mutagenesis of the histidine ligand in human lactoferrin: Iron-binding properties and crystal structure of the His253Met mutant. Biochemistry 36, 341-346.PubMedGoogle Scholar
  43. Nurizzo D, Baker HM, He Q-Y, MacGillivray RTA, Mason AB, Woodworth RC, Baker EN. 2001 Crystal structures and iron release properties of mutants (K206A and K296A) that abolish the dilysine interaction in the N-lobe of human transferrin. Biochemistry 40, 1616-1623.PubMedGoogle Scholar
  44. Octave J-N, Schneider Y-J, Trouet A, Crichton RR. 1983 Iron uptake and utilization by mammalian cells: cellular uptake of transferrin and iron. Trends Biochem Sci 8, 217-220.Google Scholar
  45. Peterson NA, Anderson BF, Jameson GB, Tweedie JW, Baker EN. 2000 Crystal structure and iron-binding properties of the R210K mutant of the N-lobe of human lactoferrin: implications for iron release from transferrins. Biochemistry 39, 6625-6633.PubMedGoogle Scholar
  46. Qiu J, Hendrixson DR, Baker EN, Murphy TF, St Geme III JW, Plaut AG. 1998 Human milk lactoferrin inactivates two putative colonization factors expressed by Haemophilus influenzae. Proc Natl Acad Sci USA 95, 12641-12646.PubMedGoogle Scholar
  47. Sharma, AK, Paramasivan, M, Srinivasan A, Yadav MP, Singh TP. 1999a Three dimensional structure of mare diferric lactoferrin at 2.6 Å resolution. J Mol Biol 289, 303-317.PubMedGoogle Scholar
  48. Sharma, AK, Rajashankar, KR, Yadav MP, Singh, TP. 1999b Crystal structure of mare apo lactoferrin: Structures of the N and C lobes are in the closed form. Acta Cryst D55, 1152-1157.Google Scholar
  49. Singh PK, Parsek MR, Greenberg EP, Welsh MJ. 2002 A component of innate immunity prevents bacterial biofilm development. Nature 417, 552-555.PubMedGoogle Scholar
  50. Suzuki YA, Shin K, Lonnerdal B. 2001 Molecular cloning and functional expression of a human intestinal Lf receptor. Biochemistry 40, 15771-15779.PubMedGoogle Scholar
  51. Van Berkel PHC, Geerts MEJ, van Veen HA, Mericskay M, de Boer HA, Nuijens JH. 1997 N-terminal stretch Arg2, Arg3, Arg4 and Arg5 of human lactoferrin is essential for binding to heparin, bacterial lipopolysaccharide, human lysozyme and DNA. Biochem J 328, 145-151.PubMedGoogle Scholar
  52. Ward PP, Zhou X, Conneely OM. 1996 Cooperative interactions between the amino-and carboxy-terminal lobes contribute to the unique iron-binding stability of lactoferrin. J Biol Chem 271, 12790-12794.PubMedGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  1. 1.School of Biological SciencesUniversity of AucklandAucklandNew Zealand
  2. 2.School of Biological SciencesNew Zealand
  3. 3.Department of ChemistryUniversity of AucklandAucklandNew Zealand

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