Lactose binding to galectin-1 modulates structural dynamics, increases conformational entropy, and occurs with apparent negative cooperativity

Irina V. Nesmelova, Elena Ermakova, Vladimir A. Daragan, Mabel Pang, Margarita Menéndez, Laura Lagartera, Dolores Solís, Linda G. Baum, Kevin H. Mayo

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


Galectins are a family of lectins with a conserved carbohydrate recognition domain that interacts with Β-galactosides. By binding cell surface glycoconjugates, galectin-1 (gal-1) is involved in cell adhesion and migration processes and is an important regulator of tumor angiogenesis. Here, we used heteronuclear NMR spectroscopy and molecular modeling to investigate lactose binding to gal-1 and to derive solution NMR structures of gal-1 in the lactose-bound and unbound states. Structure analysis shows that the Β-strands and loops around the lactose binding site, which are more open and dynamic in the unbound state, fold in around the bound lactose molecule, dampening internal motions at that site and increasing motions elsewhere throughout the protein to contribute entropically to the binding free energy. CD data support the view of an overall more open structure in the lactose-bound state. Analysis of heteronuclear single quantum coherence titration binding data indicates that lactose binds the two carbohydrate recognition domains of the gal-1 dimer with negative cooperativity, in that the first lactose molecule binds more strongly (K1=21±6×103 M-1) than the second (K2=4±2×103 M-1). Isothermal calorimetry data fit using a sequential binding model present a similar picture, yielding K1=20±10×103 M-1 and K2=1.67±0.07×103 M-1. Molecular dynamics simulations provide insight into structural dynamics of the half-loaded lactose state and, together with NMR data, suggest that lactose binding at one site transmits a signal through the Β-sandwich and loops to the second binding site. Overall, our results provide new insight into gal-1 structure-function relationships and to protein-carbohydrate interactions in general.

Original languageEnglish (US)
Pages (from-to)1209-1230
Number of pages22
JournalJournal of Molecular Biology
Issue number5
StatePublished - Apr 2010

Bibliographical note

Funding Information:
This work was supported by research grants from the National Institutes of Health ( CA 096090 to K.H.M. and GM 63281 to L.G.B.). I.V.N. was supported by the National Institutes of Health Hematology Training Grant ( HL 07062 ). This work was also supported by grants to M.M. and D.S.: BFU2006-10288 from the Spanish Ministry , an EC Marie Curie Research Training Network grant (contract no. MRTN-CT-2005-019561 ), and CIBER of Respiratory Diseases (CIBERES) , an initiative from ISCII. E.E. was supported by the RAS program “Molecular and Cellular Biology” and by a travel grant from the University of Minnesota Supercomputing Institute. The authors wish to thank the Minnesota Supercomputing Institute (University of Minnesota) for providing computer resources. NMR instrumentation was provided with funds from the National Science Foundation ( BIR-961477 ), the University of Minnesota Medical School, and the Minnesota Medical Foundation. The authors also wish to thank Dr. Yuk Sham for help with acquiring MD trajectories.


  • Carbohydrate binding
  • Galectin-1
  • MD simulations
  • NMR structure


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