title: Random mutagenesis of amelogenin for engineering protein nanoparticles.
abstract: Nanoparticles made from recombinant proteins offer excellent potential for several nanotechnological applications. However, only a very limited number of proteins are currently being used for such purposes due to limited availability and stability. Therefore, we have investigated the enamel matrix protein amelogenin as a new alternative protein for use as recombinant nanoparticles. Amelogenin is a robust protein that has the ability to self-assemble into nanosized particles termed nanospheres. This self-assembly property of amelogenin is highly pH-dependent, and modifications of the solubility behavior for amelogenin can be particularly important for some applications such as drug delivery, where responsiveness at a specific pH is an essential property. In this study, an amelogenin mutant library was created and used to screen amelogenin variants with modified solubility/aggregation profiles in response to externally applied pH changes. Fifty amelogenin mutants were identified and produced recombinantly, purified and characterized. Several mutants with distinct solubility profiles were obtained that could form uniform nanospheres, ranging from 30 to 60 nm in hydrodynamic diameter. The mutants displayed a shifted onset of pH-dependent aggregation compared to wild-type amelogenin. At physiological pH, some mutants formed soluble nanospheres, while others generated nanosphere aggregates, suggesting different practical uses for the different mutants. By mixing and co-assembling mutant and wild-type amelogenin at different ratios, the level of nanosphere aggregation could be tuned at a given pH. By exploring combinations of different amelogenin variants it is possible to control aggregation events in nanomedical applications where a specific pH response is required.
authors: Division of Pure and Applied Biochemistry, Center for Applied Life Sciences, Lund University, 221 00, Lund, Sweden. johan.bonde@tbiokem.lth.se.
authors: Johan
authors: J
authors: Bonde
authors: Division of Pure and Applied Biochemistry, Center for Applied Life Sciences, Lund University, 221 00, Lund, Sweden.
authors: Leif
authors: L
authors: Bülow
mesh_terms: D053523:Amelogenin / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism*; D054118:Nanospheres; D066329:Protein Aggregates; D015202:Protein Engineering / Q000379:methods*; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D053523:Amelogenin; D050505:Mutant Proteins; D066329:Protein Aggregates; D011994:Recombinant Proteins
keywords: amelogenin; mutant library; pH-responsive; protein nanoparticles; self- assembly