1lcv

OverviewOverview

We have studied the structural elements that affect ligand exchange, between the two high affinity biotin-binding proteins, egg white avidin, and its bacterial analogue, streptavidin. For this purpose, we have, developed a simple assay based on the antipodal behavior of the two, proteins toward hydrolysis of biotinyl p-nitrophenyl ester (BNP). The, assay provided the experimental basis for these studies. It was found that, biotin migrates unidirectionally from streptavidin to avidin. Conversely, the biotin derivative, BNP, is transferred in the opposite direction, from, avidin to streptavidin. A previous crystallographic study (Huberman, T., Eisenberg-Domovich, Y., Gitlin, G., Kulik, T., Bayer, E. A., Wilchek, M., and Livnah, O. (2001) J. Biol. Chem. 276, 32031-32039) provided insight, into a plausible explanation for these results. These data revealed that, the non-hydrolyzable BNP analogue, biotinyl p-nitroanilide, was almost, completely sheltered in streptavidin as opposed to avidin in which the, disordered conformation of a critical loop resulted in the loss of several, hydrogen bonds and concomitant exposure of the analogue to the solvent. In, order to determine the minimal modification of the biotin molecule, required to cause the disordered loop conformation, the structures of, avidin and streptavidin were determined with norbiotin, homobiotin, and a, common long-chain biotin derivative, biotinyl epsilon-aminocaproic acid., Six new crystal structures of the avidin and streptavidin complexes with, the latter biotin analogues and derivatives were thus elucidated. It was, found that extending the biotin side chain by a single CH(2) group (i.e., homobiotin) is sufficient to result in this remarkable conformational, change in the loop of avidin. These results bear significant, biotechnological importance, suggesting that complexes containing, biotinylated probes with streptavidin would be more stable than those with, avidin. These findings should be heeded when developing new drugs based on, lead compounds because it is difficult to predict the structural and, conformational consequences on the resultant protein-ligand interactions.

About this StructureAbout this Structure

1LCV is a Single protein structure of sequence from Streptomyces avidinii with SNR as ligand. Full crystallographic information is available from OCA.

ReferenceReference

Ligand exchange between proteins. Exchange of biotin and biotin derivatives between avidin and streptavidin., Pazy Y, Kulik T, Bayer EA, Wilchek M, Livnah O, J Biol Chem. 2002 Aug 23;277(34):30892-900. Epub 2002 Jun 7. PMID:12055191

Page seeded by OCA on Tue Nov 20 20:29:06 2007

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA