Structural Adaptation of a Thermostable Biotin-binding Protein in a Psychrophilic Environment.
Meir, A., Bayer, E.A., Livnah, O.(2012) J Biol Chem 287: 17951-17962
- PubMed: 22493427 
- DOI: https://doi.org/10.1074/jbc.M112.357186
- Primary Citation of Related Structures:  
3SZH, 3SZI, 3SZJ, 3T2W, 3T2X - PubMed Abstract: 
Shwanavidin is an avidin-like protein from the marine proteobactrium Shewanella denitrificans, which exhibits an innate dimeric structure while maintaining high affinity toward biotin. A unique residue (Phe-43) from the L3,4 loop and a distinctive disulfide bridge were shown to account for the high affinity toward biotin. Phe-43 emulates the function and position of the critical intermonomeric Trp that characterizes the tetrameric avidins but is lacking in shwanavidin. The 18 copies of the apo-monomer revealed distinctive snapshots of L3,4 and Phe-43, providing rare insight into loop flexibility, binding site accessibility, and psychrophilic adaptation. Nevertheless, as in all avidins, shwanavidin also displays high thermostability properties. The unique features of shwanavidin may provide a platform for the design of a long sought after monovalent form of avidin, which would be ideal for novel types of biotechnological application.
Organizational Affiliation: 
Department of Biological Chemistry, the Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel.