Source:http://linkedlifedata.com/resource/pubmed/id/12037297
Switch to
Predicate | Object |
---|---|
rdf:type | |
lifeskim:mentions | |
pubmed:issue |
Pt 6 Pt 2
|
pubmed:dateCreated |
2002-5-30
|
pubmed:abstractText |
Human lactoferrin is an iron-binding protein with a bilobal structure. Each lobe contains a high-affinity binding site for a single Fe(3+) ion and an associated CO(3)(2-) ion. Although iron binds very tightly, it can be released at low pH, with an accompanying conformational change in which the two domains move apart. The Arg121Asp (R121D) mutant of the N-lobe half-molecule of human lactoferrin was constructed in order to test whether the Asp121 side chain could substitute for the CO(3)(2-) ion at the iron-binding site. The R121D mutant protein was crystallized in its apo form as it lost iron during crystallization. The crystals were also merohedrally twinned, with a twin fraction close to 0.5. Starting from the initial molecular-replacement solution [Breyer et al. (1999), Acta Cryst. D55, 129-138], the structure has been refined at 3.0 A resolution to an R factor of 13.9% (R(free) of 19.9%). Despite the moderate resolution, the high solvent content and non-crystallographic symmetry contributed to electron-density maps of excellent quality. Weakened iron binding by the R121D mutant is explained by occlusion of the anion-binding site by the Asp side chain. The opening of the two domains in the apoR121D structure (a rotation of 54 degrees ) closely matches that of the N-lobe in full-length lactoferrin, showing that the extent of the conformational change depends on properties inherent to the N-lobe. Differences in the C-terminal portion of the N-lobe (residues 321-332) for apoR121D relative to the closed wild-type iron-bound structure point to the importance of this region in stabilizing the open form.
|
pubmed:grant | |
pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
|
pubmed:chemical | |
pubmed:status |
MEDLINE
|
pubmed:month |
Jun
|
pubmed:issn |
0907-4449
|
pubmed:author | |
pubmed:issnType |
Print
|
pubmed:volume |
58
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
955-62
|
pubmed:dateRevised |
2011-11-17
|
pubmed:meshHeading |
pubmed-meshheading:12037297-Amino Acid Substitution,
pubmed-meshheading:12037297-Arginine,
pubmed-meshheading:12037297-Aspartic Acid,
pubmed-meshheading:12037297-Crystallization,
pubmed-meshheading:12037297-Crystallography, X-Ray,
pubmed-meshheading:12037297-Humans,
pubmed-meshheading:12037297-Lactoferrin,
pubmed-meshheading:12037297-Models, Molecular,
pubmed-meshheading:12037297-Mutation,
pubmed-meshheading:12037297-Protein Conformation,
pubmed-meshheading:12037297-Protein Structure, Tertiary,
pubmed-meshheading:12037297-Transferrin
|
pubmed:year |
2002
|
pubmed:articleTitle |
Structure of a domain-opened mutant (R121D) of the human lactoferrin N-lobe refined from a merohedrally twinned crystal form.
|
pubmed:affiliation |
Department of Chemistry and Biochemistry, Massey University, Palmerston North, New Zealand.
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
|