title: The trypanosome VSG expression site encodes adenylate cyclase and a leucine-rich putative regulatory gene.
abstract: African trypanosomes are protozoan parasites that evade the host immune system by varying their dense antigenic coat. The Variant Surface Glycoprotein (VSG) is expressed exclusively from telomere-linked expression sites that contain in addition to the VSG gene, a number of open reading frames termed Expression Site Associated Genes (ESAGs). Here we demonstrate by complementation of a yeast mutant deleted for adenylate cyclase (cyr-1), that an ESAG from Trypanosoma equiperdum encodes an adenylate cyclase. Furthermore, we report that adjacent to adenylate cyclase in the expression site, is a separate open reading frame that encodes a protein sequence motif similar to the leucine-rich repeat regulatory domain of Saccharomyces cerevisiae and Schizosaccharomyces pombe adenylate cyclases. The finding of two adjacent open reading frames homologous to a single enzyme in yeast suggests that the two expression site encoded proteins may interact to regulate adenylate cyclase activity during the course of an infection.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
authors.forename: D T
authors.initials: DT
authors.lastname: Ross
authors.forename: A
authors.initials: A
authors.lastname: Raibaud
authors.forename: I C
authors.initials: IC
authors.lastname: Florent
authors.forename: S
authors.initials: S
authors.lastname: Sather
authors.forename: M K
authors.initials: MK
authors.lastname: Gross
authors.forename: D R
authors.initials: DR
authors.lastname: Storm
authors.forename: H
authors.initials: H
authors.lastname: Eisen
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015971:Gene Expression Regulation, Enzymologic; D005800:Genes, Fungal; D005809:Genes, Regulator; D007930:Leucine / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D010957:Plasmids; D016053:RNA, Protozoan / Q000032:analysis; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014345:Trypanosoma / Q000235:genetics*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000235:genetics*
chemical_list: D016053:RNA, Protozoan; D014643:Variant Surface Glycoproteins, Trypanosoma; D000262:Adenylyl Cyclases; D007930:Leucine