A Biological Multifunctional Nanomaterial Based On Self-assembly Of S-layer Protein Of Bacillus Anthracis

With the development of science and technology,nanomaterials have been entered our daily life quickly.There are many nanomaterials that are from natural biological source,which are called biological nanomaterials.Bacterial surface protein(S-layer protein)is one of the biological nanomaterials.S-layer protein exists in most Archaea and eubacteria’s suface.It consists of a kind of protein or glycoprotein.It is an ideal biological nanomaterial which can self-assemble into lattice structure on the bacterial surface and in vitro.In the last few decades,scientists have been interested in the study of S-layer protein,which is based on the large amount of expression,and the properties of self assembly,so many applications such as high efficiency,surface display,preparation of molecular sieve and template of metal nanoparticles are developed.These studies show that S-layer is an ideal biological material.The S-layer protein of Bacillus anthracis EA1 was studied as the object in this study.We combined the self-assembling properties and biological function of EA1,developed a new multifunctional biological nano materials:1.We expressed the Bacillus anthracis S-layer protein EA1 in vitro,and studied the best condition of self-assembly in different interface;Methyl Parathion Hydrolase(MPH)as a marker enzyme for fusion to the C-terminus of EA1 to obtain the assembly of the fusion protein EA1-MPH.Using transmission electron microscopy techniques we get the EA1 and fusion protein EA1-MPH crystal lattice structure and parameters successfully.The EA1-MPH applied in detection of serum of Bacillus anthracis in antibody,which makes full use of the EA1 self assembling properties and its biological antigenicity.At the same time also used the MPH enzyme activity.Characteristics of the both proteins of physical,chemical and biological characteristics had fully displayed.Ultrasensitive detection of this method to detect the Bacillus anthracis specific antibody and the detection sensitivity achived to pg level,compared with traditional method,the sensitivity increased about 300 times.Furthermore,the result could be seen by naked eyes because the the products were yellow.Meanwhile,we found that the chimeric nanomaterial was a kind of multifunctional nanomaterial since it obviously enhanced the stability of MPH and it also had a murein hydrolase activity as EA1.2.A biological nanomaterial which could recycle enzyme activity quickly:Bacillus anthracis S-layer protein EA1 could self-assemble on the magnetic liposome,based on that,we developed a method that could multiple and rapid recover enzyme(MPH and glucose oxidase).At the same time,we proved that the S-layer protein EA1 self-assembled on liposome could stabilize the liposomes morphology effectively.Above works provide a foundation for the development and application of S-layer protein in future.Here,the S-layer protein EA1 was seen as a carrier to let the enzyme in magnetic liposome surface immobilization and array arrangement.This developed a general strategy for the storage,recycling and reuse of enzyme.