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Domain closure in lactoferrin. Two hinges produce a see-saw motion between alternative close-packed interfaces.

Abstract：

:Lactoferrin is an iron transport protein. Upon binding iron, the two domains in the N-terminal half of the molecule move together. Previous work has shown that this domain closure involves two hinges. Using the newly refined structure of the open form, the structural mechanism underlying this motion is analyzed here in detail. 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. Lactoferrin provides a particularly clear example of the general features of hinged domain motion. It is compared to other instances of hinged domain closure and contrasted with instances of shear domain closure, where the overall motion is a summation of many small sliding motions between close-packed segments of polypeptide.

journal_name

J Mol Biol

journal_title

Journal of molecular biology

authors

Gerstein M,Anderson BF,Norris GE,Baker EN,Lesk AM,Chothia C

doi

10.1006/jmbi.1993.1592

subject

Has Abstract

pub_date

1993-11-20 00:00:00

pages

357-72

issue

eissn

0022-2836

issn

1089-8638

pii

S0022-2836(83)71592-5

journal_volume

234

pub_type

杂志文章

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Domain closure in lactoferrin. Two hinges produce a see-saw motion between alternative close-packed interfaces.