Characterization of a Relatively Rare Class B, Type 2 Trypanosome Variant Surface Glycoprotein Gene

• Published in: The Journal of parasitology 1998-04, Vol.84 (2), p.284-292
• Main Authors: SCHOPF, L. R, MANSFIELD, J. M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; Blotting, Northern; Blotting, Southern; Chromosomes; Classical genetics, quantitative genetics, hybrids; Complementary DNA; DNA; DNA Restriction Enzymes; DNA, Protozoan - analysis; Electrophoresis, Gel, Pulsed-Field; Fundamental and applied biological sciences. Psychology; Gels; Genes; Genetics of eukaryotes. Biological and molecular evolution; Genetics-Evolution; Genomics; Membrane glycoproteins; Mice; Molecular Sequence Data; Molecules; Parasitology; Protozoa; RNA, Protozoan - analysis; Species Specificity; Trypanosoma brucei rhodesiense - genetics; Trypanosome; Variant Surface Glycoproteins, Trypanosoma - chemistry; Variant Surface Glycoproteins, Trypanosoma - genetics
• ISSN: 0022-3395; 1937-2345
• DOI: 10.2307/3284484

The variant surface glycoprotein (VSG) gene of Trypanosoma brucei rhodesiense LouTat 1.5, a defined African trypanosome variant antigenic type, was cloned and sequenced. Southern blot analysis revealed 2 DNA restriction fragments in both VSG 1.5 expressor and nonexpressor populations, suggesting that there are 2 genomic copies of the VSG 1.5 gene and no expression-linked copies. Pulsed-field gel electrophoresis followed by Southern blot analysis showed that each copy of the VSG 1.5 gene exists on a separate large chromosome in both the expressor (approximately 3.5- and 4-megabase (Mb) chromosomes) and nonexpressor (approximately 4- and 5.7-Mb chromosomes) populations. Thus, VSG genes may be present on larger chromosomes than previously reported. Sequence analysis and alignments revealed that the VSG 1.5 molecule is a class B VSG with 12 cysteine residues in the N-terminus and is classified as a type 2 VSG based on C-terminus motifs. This classification shows that the VSG 1.5 molecule represents a relatively rare VSG class and type. Taken together, these studies provide additional information on VSG genes and proteins and supply the foundation for structure-function analysis of the VSG 1.5 surface antigen expressed by trypanosomes of the LouTat 1 serodeme.