1l5t: Difference between revisions

{{Structure

|PDB= 1l5t |SIZE=350|CAPTION= <scene name='initialview01'>1l5t</scene>, resolution 3.00&Aring;

|SITE=  

|LIGAND=  

|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Diferric-transferrin_reductase Diferric-transferrin reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.16.1.2 1.16.1.2] </span>

|GENE=  

|RELATEDENTRY=[[1cb6|1cb6]], [[1lct|1lct]]

|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1l5t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1l5t OCA], [http://www.ebi.ac.uk/pdbsum/1l5t PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1l5t RCSB]</span>

'''Crystal Structure of a Domain-Opened Mutant (R121D) of the Human Lactoferrin N-lobe Refined From a Merohedrally-Twinned Crystal Form.'''

==Overview==

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.

 

==About this Structure==

1L5T is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1L5T OCA].

 

Structure of a domain-opened mutant (R121D) of the human lactoferrin N-lobe refined from a merohedrally twinned crystal form., Jameson GB, Anderson BF, Breyer WA, Day CL, Tweedie JW, Baker EN, Acta Crystallogr D Biol Crystallogr. 2002 Jun;58(Pt 6 Pt 2):955-62. Epub, 2002 May 29. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12037297 12037297]

[[Category: Single protein]]

[[Category: Anderson, B F.]]

[[Category: Baker, E N.]]

[[Category: Breyer, W A.]]

[[Category: Jameson, G B.]]

[[Category: Tweedie, J W.]]