A monocistronic transcript for a trypanosome variant surface glycoprotein.
Many protein-encoding genes of African trypanosomes are transcribed as large polycistronic pre-mRNAs that are processed into individual mRNAs containing a 5' spliced leader and 3' poly(A). The 45- to 60-kb pre-mRNAs encoding some variant surface glycoproteins (VSGs) contain as many as eight unrelated coding regions. Here we identify the promoter for a metacyclic VSG gene that is expressed without duplication in a bloodstream trypanosome clone. This 70-bp promoter is located 2 kb upstream of the telomere-linked VSG gene and directs the synthesis of a monocistronic VSG pre-mRNA lacking the 5' spliced leader. Its sequence only slightly resembles those of other known trypanosome promoters, but it does cross-hybridize with several related sequences elsewhere in the genome. These results suggest that a new class of trypanosome promoters has been found, whose function is to initiate monocistronic transcription of those VSG genes normally expressed during the metacyclic stage.
Human Nutrition Program, University of Iowa, Iowa City 52242.
C M
CM
Alarcon
H J
HJ
Son
T
T
Hall
J E
JE
Donelson
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015870:Gene Expression; D005786:Gene Expression Regulation; D005796:Genes; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics*; D016053:RNA, Protozoan / Q000235:genetics*; D015183:Restriction Mapping; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013329:Structure-Activity Relationship; D016833:Trypanosoma brucei rhodesiense / Q000235:genetics*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000235:genetics*
D012333:RNA, Messenger; D016053:RNA, Protozoan; D014643:Variant Surface Glycoproteins, Trypanosoma