Structure of mare apolactoferrin: the N and C lobes are in the closed form.
Abstract: The structure of mare apolactoferrin (MALT) has been determined at 3. 8 A resolution by the molecular-replacement method, using the structure of mare diferric lactoferrin (MDLT) as the search model. The MDLT structure contains two iron-binding sites: one in the N-terminal lobe, lying between domains N1 and N2, and one in the C-terminal lobe between domains C1 and C2. Both lobes have a closed structure. MALT was crystallized using the microdialysis method with 10%(v/v) ethanol in 0.01 M Tris-HCl. The structure has been refined to a final R factor of 0.20 for all data to 3.8 A resolution. Comparison of the structure of MALT with that of MDLT showed that the domain arrangements in these structures are identical. However, the structure of MALT is very different to the structures of human apolactoferrin (HALT) and duck apo-ovotransferrin (DAOT), in which the domain associations differ greatly. In HALT, the N lobe adopts an open conformation while the C lobe is in the closed form. On the other hand, in DAOT both the N and the C lobes adopt the open form. These results indicate the domain arrangements in these proteins to be an important structural feature related to their specific biological functions. Based on the structures of MALT, HALT and DAOT, it can be stated that the native apoproteins of the transferrin family adopt three forms: (i) with both the N and the C lobes in closed forms, as observed in MALT, (ii) with the N lobe open and the C lobe closed, as observed in HALT, and (iii) with both the N and the C lobes open, as found in DAOT. All these proteins attain a convergent form when iron is bound to them, suggesting an efficient and unique form of iron binding. The interface between the N and C lobes, which is formed by N1-C1 contact in the core of the molecule, does not change significantly.
Publication Date: 1999-05-18 PubMed ID: 10329777DOI: 10.1107/s0907444999003807Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article presents a detailed study of the structure of mare apolactoferrin (MALT), a type of protein in the transferrin family, which is known for its iron-binding ability. Using the structure of mare diferric lactoferrin (MDLT) as a reference model, the researchers found that the MALT protein has two distinct sections, or “lobes,” both of which have a closed form.
Structure Determination and Comparison
- The researchers determined the structure of MALT at 3.8 A resolution through the molecular-replacement method and used the structure of MDLT as the search model.
- Within the MDLT structure, two iron-binding sites exist: one in the N-terminal lobe and one in the C-terminal lobe.
- The structure of MALT has been refined to a final R factor of 0.20 across all data.
- Though the structure of MALT and MDLT are identical, differences were observed when compared to the structures of human apolactoferrin (HALT) and duck apo-ovotransferrin (DAOT).
Distinct Forms of the Transferrin Family
- In HALT, the N lobe assumes an open form while the C lobe exhibits a closed form, and in DAOT, both the N and C lobes assume an open form.
- This suggests that the structural arrangement within these proteins is significant as it relates to their specific biological functions.
- Three forms are observed in native apoproteins of the transferrin family: MALT with both lobes in closed forms, HALT with the N lobe open and the C lobe closed, and DAOT with both lobes open.
Iron Binding and Structural Stability
- All these proteins achieve a converging form when iron is bound to them, indicating a unique and efficient method of binding iron.
- The interface between the N and C lobes, formed by N1-C1 contact in the core of the molecule, does not change significantly, showing a high degree of structural stability.
In summation, the research elucidates the unique structural formats of proteins in the transferrin family and emphasizes their inherent ability to bind iron efficiently. The structure and function relationship these proteins hold is potentially an important factor in understanding their biological functions.
Cite This Article
APA
Sharma AK, Rajashankar KR, Yadav MP, Singh TP.
(1999).
Structure of mare apolactoferrin: the N and C lobes are in the closed form.
Acta Crystallogr D Biol Crystallogr, 55(Pt 6), 1152-1157.
https://doi.org/10.1107/s0907444999003807 Publication
Researcher Affiliations
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India.
MeSH Terms
- Animals
- Apoproteins / chemistry
- Crystallography, X-Ray
- Female
- Horses
- Humans
- Lactoferrin / chemistry
- Models, Molecular
- Protein Conformation
Citations
This article has been cited 4 times.- Kumar S, Sharma D, Kumar R, Kumar R. Electrostatic effects control the stability and iron release kinetics of ovotransferrin.. J Biol Inorg Chem 2014 Aug;19(6):1009-24.
- Sharma S, Sinha M, Kaushik S, Kaur P, Singh TP. C-lobe of lactoferrin: the whole story of the half-molecule.. Biochem Res Int 2013;2013:271641.
- Rinaldo D, Field MJ. A computational study of the open and closed forms of the N-lobe human serum transferrin apoprotein.. Biophys J 2003 Dec;85(6):3485-501.
- Baker HM, Anderson BF, Baker EN. Dealing with iron: common structural principles in proteins that transport iron and heme.. Proc Natl Acad Sci U S A 2003 Apr 1;100(7):3579-83.
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