title: Cloning of the surface layer gene sllB from Bacillus sphaericus ATCC             14577 and its heterologous expression and purification.
abstract: A cDNA fragment encoding the S-layer protein SllB cloned from Bacillus sphaericus ATCC 14577 was expressed on the surface of E. coli BL21 (DE3) cells and confirmed by the square lattice structure at the nanoscale level. The amplified gene fragment designed with PCR primers from a specified reference sequence (GenBank accession no. AJ849550) showed a high degree of sequence identity with the known sequences for S-layer protein. The best alignment scores were seen in B. sphaericus strains JG-A12 and NCTC9602, which code for a pre-form protein with a predicted cleavage site located between the two alanine residues 31 and 32. After this signal peptide sequence was removed, the mature protein had a molecular mass of 116.2613 kDa and a theoretical pI of 5.40. Further bioinformatic analysis revealed three S-layer homology (SLH) domains in the N-terminus of the mature protein, positioned at the 1-61, 63-128 and 137-197 residues. The mature S-layer protein was composed of alpha helices (24.86%), extended strands (27.01%), and rich random coils (48.13%). Bioinformatics-driven characterization of SllB may provide scientific evidence for further application of this gene in the fields of nanobiotechnology and biomimetics in the future.
authors.affiliation: Department of Laboratory Medicine, Yancheng Health Vocational and Technical College, Yancheng 224006, Jiangsu Province, PR China. ybcui1975@hotmail.com
authors.forename: Yu-Bao
authors.initials: YB
authors.lastname: Cui
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Wei-Na
authors.initials: WN
authors.lastname: Liu
authors.forename: Qing-Wen
authors.initials: QW
authors.lastname: Chen
authors.forename: Gui-Fang
authors.initials: GF
authors.lastname: Ma
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Shi
authors.forename: Yun-Gang
authors.initials: YG
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D003001:Cloning, Molecular; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification; D015964:Gene Expression Regulation, Bacterial; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010957:Plasmids; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; C055764:S-layer proteins