Crystallization and preliminary X-ray analysis of W120K mutant of streptavidin

Y. Pazy, O. H. Laitinen, B. Ravoy, M. S. Kulomaa, M. Wilchek, E. A. Bayer, O. Livnah*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Bacterial streptavidin and chicken avidin are homotetrameric proteins that share an exceptionally high affinity towards the vitamin biotin. The biotin-binding sites in both proteins contain a crucial tryptophan residue contributed from an adjacent subunit. This particular tryptophan (W110 in avidin and W120 in streptavidin) plays an important role in both biotin binding and in the quaternary stabilities of the proteins. An intriguing naturally occurring alteration of tryptophan to lysine was previously described in the C-terminal domain of sea-urchin fibropellins, which share a relatively high sequence similarity with avidin and streptavidin. Avidin (Avm-W110K) and streptavidin (Savm-W120K) mutations show substantially reduced affinities towards biotin as well as the dissociation of their tetrameric structure into stable avidin and streptavidin dimers. Savm-W120K was crystallized at 293 K using the hanging-drop vapour-diffusion method. The crystals diffract to 1.7 resolution using synchrotron radiation and belong to the monoclinic space group P21, with unit-cell parameters a = 50.43, b = 100.41, c = 52.51 Å, β = 112.12°. The asymmetric unit contains four molecules of Savm-W120K, with a corresponding VM of 2.3 Å3 Da-1 and a solvent content of 46%.

Original languageAmerican English
Pages (from-to)1885-1886
Number of pages2
JournalActa Crystallographica Section D: Biological Crystallography
Issue number12
StatePublished - 2001


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