Function of N-terminal import signals in trypanosome microbodies.
The glycosomes of trypanosomes are related to eukaryotic peroxisomes. For many glycosomal and peroxisomal proteins, a C-terminal SKL-like tripeptide known as PTS-1 serves as the targeting signal. For peroxisomes, a second N-terminal signal (PTS-2) was demonstrated on rat 3-ketoacyl-CoA thiolase. Several glycosomal proteins do not bear a PTS-1. One such protein, fructose bisphosphate aldolase, has a PTS-2 homology at its N-terminus. To find out whether the PTS-2 pathway exists in trypanosomes, we expressed chloramphenicol acetyltransferase fusion proteins bearing N-terminal segments of either rat thiolase or trypanosome aldolase. The mammalian PTS-2 clearly mediated glycosomal import. The aldolase N-terminus mediated import with variable efficiency depending on the length of the appended sequence. These results provide evidence for the existence of the PTS-2 pathway in trypanosomes.
Blattner
J
J
Zentrum für Molekulare Biologie, Universität Heidelberg, Germany.
Dörsam
H
H
Clatyon
C E
CE
D000101:Acetyl-CoA C-Acetyltransferase / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation; D016384:Consensus Sequence; D017931:DNA Primers / Q000737:chemistry; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry / Q000378:metabolism; D008830:Microbodies / Q000201:enzymology*; D008969:Molecular Sequence Data; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014345:Trypanosoma / Q000201:enzymology* / Q000235:genetics
D017931:DNA Primers; D018160:Receptors, Cytoplasmic and Nuclear; D000101:Acetyl-CoA C-Acetyltransferase; D005634:Fructose-Bisphosphate Aldolase