Motion in Lactoferrin [lf]

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Classification Known Domain Motion, Hinge Mechanism [D-h-2]

Structures
1LFG Open Conformation [ PartsList ]
1LFH Closed Conformation [ PartsList ]

Description
2 interdomain linkages, 2 hinges (in a beta-sheet), 53 degree rotation. See-saw between two interfaces. Lactoferrin is an iron transport protein. Upon binding iron, the two domains in the N-terminal half of the molecule close, in a motion involving two hinges. Upon closure the domains rotate 54 degrees essentially as rigid bodies. The axis of rotation passes through the two beta-strands linking the domains. These strands contain hinges in the sense that three large torsion angle changes are responsible for the bulk of the motion while smaller torsion angle changes in neighboring residues are responsible for the remainder of the motion. The rotation axes of these three torsion angle changes are nearly parallel to the axis of the overall 54 degrees rotation, so the local motion in the hinges can be directly related to the overall motion. A crucial feature of the hinge residues is that they have very few packing constraints on their main-chain atoms. The domains make different packing contacts with each other in the open and closed forms. These contacts form two interdomain interfaces arranged on either side of the hinges. Pivoting about the hinges produces a see-saw motion between the two interfaces. That is, when the domains close down, residues in the interface on one side of the hinges become buried and close-packed and residues on the other side become exposed. The situation is reversed when the domains open up.

Particular values describing motion
Domain 1 (residue selection) = 1-92 252-333
Domain 2 (residue selection) = 93-251
Location of a Hinge (residue selection) = 249-252 (second hinge)
Location of a Hinge (residue selection) = 89-92 (first hinge)
Experimental Methods = x (Traditional x-ray)
Creation Date = 19970822
Modification Date = 19970822

References
B F Anderson, H M Baker, G E Norris, S V Rumball and E N Baker (1990). Apolactoferrin structure demonstrates ligand-induced conformational change in transferrins. Nature. 344: 784-787. [Medline info for 91295198]
M Gerstein, A M Lesk, E N Baker, B Anderson, G Norris and C Chothia (1993). Domain Closure in Lactoferrin: Two Hinges produce a See-saw Motion between Alternative Close-Packed Interfaces. J. Mol. Biol. 234: 357-372. [Medline info for 94047086]

Data and Graphics
Graphic-1 The overall rotation, showing the tight packing of interfaces in the closed form. (Copyright Biochemistry, 1994)
MOVIES A page giving pointers to movies of the motion.

GO terms associated with structures
Molecular functionferric iron binding
Cellular componentextracellular region
Biological processiron ion homeostasis, iron ion transport

Morphs

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Best representative
Morph Morph name Structure #1 Structure #2 Residues
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Copyright 1995-2005 M. Gerstein, W. Krebs, S. Flores, N. Echols, and others
Email: Mark.Gerstein _at_ yale.edu