Secondary structure and 3D homology modeling of swine leukocyte antigen class 2 (SLA-2) molecules.
No information to date is available to elucidate the structure of swine leukocyte antigen class I (SLA-I) molecule which is comprised by a heavy chain of SLA-I non-covalently associated with a light chain, beta(2)-microglobulin (beta(2)m) proteins. Presently, one of SLA-I gene SLA-2 and beta(2)m gene were expressed as soluble maltose binding proteins (MBP-proteins) in a pMAL-p2X/Escherichia coli TB1 system and identified by western blotting with anti-MBP polyclonal antibodies. The expressed proteins MBP-SLA-2 and MBP-beta(2)m were purified on amylose affinity columns followed by DEAE-Sepharose. The purified products were cleaved by Factor Xa, respectively, and the interest of proteins SLA-2 and beta(2)m were purified on amylose affinity columns followed by separation from MBP on DEAE-Sepharose. The secondary structures of SLA-2 and beta(2)m were analyzed by circular dichroism (CD) spectrophotometry. The three-dimensional (3D) structure of their peptide-binding domain (PBD) was modeled-based sequence homology. The content of the alpha-helix, beta-sheet, turn, and random coil in the SLA-2 protein were 76, 95, 36, and 67aa, respectively. In the 98aa of beta(2)m, the contents of the alpha-helix, beta-sheet, turn, and random coil were 0, 45, 8, and 45aa, respectively. The SLA-2 protein displayed a typical alpha-helix structure while beta(2)m protein displayed a typical beta-sheet structure. Homology modeling of the SLA-2 and beta(2)m proteins demonstrated similarities with the structure of human and mouse MHC (major histocompatibility complex) class I proteins.
Gao
Feng-Shan
FS
Department of Biochemistry and Molecular Biology, College of Bioengineering, Dalian University, Dalian, Liaoning 116622, China. gfsh0626@126.com
Xu
Chong-bo
CB
Long
Yi-hou
YH
Xia
Chun
C
D000688:Amylose / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002846:Chromatography, Affinity; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics*; D015951:Factor Xa / Q000378:metabolism; D015870:Gene Expression / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000949:Histocompatibility Antigens Class II; D006801:Humans; D058619:Maltose-Binding Proteins; D051379:Mice; D008956:Models, Chemical; D015202:Protein Engineering; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D040681:Structural Homology, Protein; D013552:Swine; D001613:beta 2-Microglobulin / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D058619:Maltose-Binding Proteins; D011993:Recombinant Fusion Proteins; D001613:beta 2-Microglobulin; C438668:swine leukocyte antigen; D000688:Amylose; D015951:Factor Xa