3KIH

The crystal structures of two fragments truncated from 5-bladed beta-propeller lectin, tachylectin-2 (Lib2-D2-15)

Summary for 3KIH

• Entry DOI: 10.2210/pdb3kih/pdb
• Related: 3KIF
• Descriptor: 5-bladed beta-propeller lectin, 2-(acetylamido)-2-deoxy-D-glucono-1,5-lactone (3 entities in total)
• Functional Keywords: 5-bladed beta-propeller, structural genomics, israel structural proteomics center, ispc, sugar binding protein
• Biological source: synthetic construct
• Total number of polymer chains: 5
• Total formula weight: 54966.87

Authors

Dym, O.,Tawfik, D.S.,Yadid, I.,Israel Structural Proteomics Center (ISPC) (deposition date: 2009-11-02, release date: 2010-04-28, Last modification date: 2023-11-01)

Primary citation

Yadid, I.,Kirshenbaum, N.,Sharon, M.,Dym, O.,Tawfik, D.S.
Metamorphic proteins mediate evolutionary transitions of structure
Proc.Natl.Acad.Sci.USA, 107:7287-7292, 2010

PubMed Abstract: The primary sequence of proteins usually dictates a single tertiary and quaternary structure. However, certain proteins undergo reversible backbone rearrangements. Such metamorphic proteins provide a means of facilitating the evolution of new folds and architectures. However, because natural folds emerged at the early stages of evolution, the potential role of metamorphic intermediates in mediating evolutionary transitions of structure remains largely unexplored. We evolved a set of new proteins based on approximately 100 amino acid fragments derived from tachylectin-2--a monomeric, 236 amino acids, five-bladed beta-propeller. Their structures reveal a unique pentameric assembly and novel beta-propeller structures. Although identical in sequence, the oligomeric subunits adopt two, or even three, different structures that together enable the pentameric assembly of two propellers connected via a small linker. Most of the subunits adopt a wild-type-like structure within individual five-bladed propellers. However, the bridging subunits exhibit domain swaps and asymmetric strand exchanges that allow them to complete the two propellers and connect them. Thus, the modular and metamorphic nature of these subunits enabled dramatic changes in tertiary and quaternary structure, while maintaining the lectin function. These oligomers therefore comprise putative intermediates via which beta-propellers can evolve from smaller elements. Our data also suggest that the ability of one sequence to equilibrate between different structures can be evolutionary optimized, thus facilitating the emergence of new structures.

PubMed: 20368465
DOI: 10.1073/pnas.0912616107

Experimental method

X-RAY DIFFRACTION (2.49 Å)