6LF3

3D domain-swapped dimer of the maltose-binding protein fused to a fragment of the protein-tyrosine kinase 2-beta

Summary for 6LF3

• Entry DOI: 10.2210/pdb6lf3/pdb
• Related: 6LES
• Related PRD ID: PRD_900001
• Descriptor: Maltose/maltodextrin-binding periplasmic protein,Protein-tyrosine kinase 2-beta, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose (2 entities in total)
• Functional Keywords: maltose binding protein, domain-swapping, arm exchange, folding, passenger protein, surface entropy reduction, fixed-arm carrier, dimer, pyk2, apo-protein, sugar binding protein
• Biological source: Escherichia coli (strain K12); More
• Total number of polymer chains: 6
• Total formula weight: 280439.25

Authors

Momin, A.A.,Shahul Hameed, U.F.,Arold, S.T. (deposition date: 2019-11-28, release date: 2019-12-11, Last modification date: 2023-11-22)

Primary citation

Momin, A.A.,Hameed, U.F.S.,Arold, S.T.
Passenger sequences can promote interlaced dimers in a common variant of the maltose-binding protein.
Sci Rep, 9:20396-20396, 2019

PubMed Abstract: The maltose-binding protein (MBP) is one of the most frequently used protein tags due to its capacity to stabilize, solubilize and even crystallize recombinant proteins that are fused to it. Given that MBP is thought to be a highly stable monomeric protein with known characteristics, fused passenger proteins are often studied without being cleaved from MBP. Here we report that a commonly used engineered MBP version (mutated to lower its surface entropy) can form interlaced dimers when fused to short protein sequences derived from the focal adhesion kinase (FAK) or the homologous protein tyrosine kinase 2 (PYK2). These MBP dimers still bind maltose and can interconvert with monomeric forms in vitro under standard conditions despite a contact surface of more than 11,000 Å. We demonstrate that both the mutations in MBP and the fused protein sequences were required for dimer formation. The FAK and PYK2 sequences are less than 40% identical, monomeric, and did not show specific interactions with MBP, suggesting that a variety of sequences can promote this MBP dimerization. MBP dimerization was abrogated by reverting two of the eight mutations introduced in the engineered MBP. Our results provide an extreme example for induced reversible domain-swapping, with implications for protein folding dynamics. Our observations caution that passenger-promoted MBP dimerization might mislead experimental characterization of the fused protein sequences, but also suggest a simple mutation to stop this phenomenon.

PubMed: 31892719
DOI: 10.1038/s41598-019-56718-y

Experimental method

X-RAY DIFFRACTION (3.2 Å)