Evidence for segmental gene conversion between a cognate hsp 70 gene and the temperature-sensitively transcribed hsp70 genes of Trypanosoma brucei.
The protozoan parasite Trypanosoma brucei expresses several heat shock proteins of 70 kDa (hsp70). We show that, from 5' to 3', a diverged cognate hsp70 gene (gene 1) is separated by about 6 kb of DNA from a cluster of five identical hsp70 genes (genes 2-6). The hsp70 cognate gene has a predicted open reading frame of 676 amino-acids. The steady-state mRNA levels of gene 1 are unaffected by temperature shifts up to 42 degrees C. Hsps of diverse organisms share several fully conserved amino acid domains in the N-terminal region of the hsp70 proteins. These conserved amino acid domains are also observed in the T. brucei hsp70 genes 1-6. However they are, in contrast to the heat shock genes of other eukaryotes, encoded by nucleotide sequence blocks that are identical in all six hsp70 genes. These conserved domains, located in the 5' coding region, range in size from several to hundreds of nucleotides and are separated by highly diverged nucleotide sequences. The nucleotide sequence conservation between hsp70 gene 1 and hsp70 genes 2-6 indicates that selective sequence homogenization, presumably through gene conversion, maintained the amino acid sequence conservation.
Department of Genetics and Development, Columbia University, New York, NY 10032.
M G
MG
Lee
R I
RI
Polvere
L H
LH
Van der Ploeg
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005785:Gene Conversion; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D013696:Temperature; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000235:genetics*
D006360:Heat-Shock Proteins