OBJECTIVETo express the carbohydrate recognition domain (CRD) of Balb/C mouse mannan binding lectin A (MBL-A) in E.coli.

METHODSThe target gene fragment was obtained by PCR from the plasmid pmMBL-A harboring mouse MBL-A gene. The PCR product was recombined with the prokaryotic expression vector pET-41a(+) and the resulting recombinant plasmid was identified by PCR, restriction analysis and sequencing before transformation into E.coli BL21(DE3) cell for expression of the target protein. After washing and renaturation, the protein was purified on GST-Tag purification resins and analyzed by SDS-PAGE, Western blotting and enzyme-linked immunosorbent assay (ELISA).

RESULTSA DNA fragment of about 450 bp was amplified by PCR and the recombinant plasmid pET41a-mMBL-A-CRD was constructed by linking the fragment with pET41a(+) vector. The result of restriction enzyme analysis and sequencing of the selected clones were consistent with those by computer analysis. The recombinant vector was expressed in E.coli BL21(DE3), and the expressed protein existed mainly as inclusion bodies, whose relative molecular mass was about 47,000 by SDS-PAGE analysis. After washing, renaturation and purification, the purity of recombinant protein was about 90%. Western blotting suggested immunoreactivity of the purified protein with anti-GST antibody, and its sugar binding activity was verified by ELISA.

CONCLUSIONWe have successfully obtained mouse MBL-A CRD protein, which provides the base for further functional study of the MBL-A molecule.

Animals ; Carbohydrates ; chemistry ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Inclusion Bodies ; metabolism ; Mannose-Binding Lectin ; biosynthesis ; chemistry ; genetics ; Mice ; Mice, Inbred BALB C ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; genetics

The genomic DNA were extracted from the leaves of Polygonatum roseum (Liliaceae) in Xinjiang and the primers were designed according to conservative sequences of Polygonatum lectins gene. The complete ORF of Polygonatum roseum agglutinin (PRA) gene was amplified as a fragment of 550 bp, which was identical with predicted size. Like most of the plant lectin genes, there was no intron in the PRA gene. The ORF of the gene encoded 159 amino acid residues, in which included a signal sequence of 28 amino acid residues at its N-terminus. The cDNA sequence had 92% identities compared with the published sequence. The amino acid sequence and SWISS-MODEL analysis indicated that the three-dimensional structure of PRA strongly resembled with that of monocot mannose-binding lectins, which comprised with three antiparallel four-stranded beta-sheets arranged as a 12-stranded beta-barrel. The recombinant pGEX4T-1-PRA and pMAL-p2x-PRA prokaryotic expression vectors were constructed to produce GST-PRA and MBP-PRA fusion proteins in E. coli, respectively. SDS-PAGE of the fusion protein demonstrated that the PRA lectin protein migrated at a size of 14 kD. The immunization was performed by intra-muscular injection of pcDNA3-PRA, and the antiserum was detected by ELISA. Western blotting analysis showed the antiserum specifically bound the lectin protein. The establishment of such an expression system might provide materials for further investigation of the properties and functions of PRA proteins. It also laid the basis for plant genetic engineering on its defensive functions to pests and diseases.
Amino Acid Sequence ; Animals ; Base Sequence ; China ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Female ; Mannose-Binding Lectin ; biosynthesis ; genetics ; Mice ; Molecular Sequence Data ; Polygonatum ; chemistry ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology ; Sequence Analysis

Mannose-binding lectin (MBL) plays an important role in immune defense. This study was undertaken to investigate the association between hepatitis B virus infection and polymorphisms of MBL gene. We assessed the single nucleotide polymorphism at codon 54 in exon 1 of MBL in patients with hepatitis B virus infection and HBsAg negative controls in Korean population. A total of 498 enrolled subjects was classified into four groups. Group 1; Clearance, Group 2; Inactive healthy carrier, Group 3; Chronic hepatitis, Group 4; Liver cirrhosis. MBL gene polymorphisms at codon 54 led to three genotypes (G/G, G/A, A/A). When we divided subjects into clearance group (group 1) and persistence group (group 2-4), G/G genotype and A-allele carrier were observed in 55.6% and 44.4% in clearance group, 64.8% and 35.2% in persistence group (p=0.081), respectively. When hepatitis B virus persistent cases were divided into inactive healthy carrier (group 2) and disease progression group (group 3 and 4), MBL gene polymorphisms at codon 54 were not related to disease progression (p=0.166). MBL gene polymorphism at codon 54 was not associated with the clearance of hepatitis B virus infection nor progression of disease in chronic hepatitis B virus infection.
Adult ; Alleles ; Codon ; Disease Progression ; Female ; Fibrosis ; Genotype ; Hepatitis ; Hepatitis B/*genetics/*metabolism ; Hepatitis B virus/*metabolism ; Heterozygote ; Humans ; Korea ; *Lectins ; Male ; Mannose-Binding Lectin/*chemistry/*genetics ; Middle Aged ; *Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Research Support, Non-U.S. Gov't