Glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a COOH-terminal microbody targeting signal.

Blattner, Judith; Swinkels, B.W.; Dörsam, Heinz; Prospero, Terence D.; Subramani, Suresh; Clayton, Christine

doi:10.1083/jcb.119.5.1129

Cited by 114 publications

(72 citation statements)

References 42 publications

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“…This and other kinetoplastids are distinguished from diverse eucaryotic cells by the presence of glycosomes, a microbody-like organelle containing glycolytic and glycerol metabolic enzymes (Opperdoes 1987, Michels 1989, Blattner et al 1992. Corresponding glycolytical isoenzymes were also found to be present in the cytoplasm of most protozoa studied so far.…”

mentioning

confidence: 96%

Purification and Partial Characterization of Trypanosoma cruzi Triosephosphate Isomerase

Bourguignon

Pacheco

et al. 1998

Mem. Inst. Oswaldo Cruz

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mentioning

confidence: 96%

Purification and Partial Characterization of Trypanosoma cruzi Triosephosphate Isomerase

Bourguignon

Pacheco

et al. 1998

Mem. Inst. Oswaldo Cruz

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“…Morphologically, the glycosomes closely resemble the peroxisomes found in higher eukaryotes, although their enzyme contents differ significantly [2]. Recent studies indicated that the import of proteins into the glycosome depends on a conserved C-terminal tripeptide motif, analogous to the C-terminal serine-lysine-leucine (SKL) sequence responsible for peroxisomal targeting of firefly luciferase [3,4]. Subsequent investigations showed that the C-terminal tripeptide sequence requirements for glycosomal import are considerably more relaxed than those for import of proteins into mammalian peroxisomes .…”

Section: Introductionmentioning

confidence: 99%

Phosphoenolpyruvate carboxykinase of Trypanosoma brucei is targeted to the glycosomes by a C‐terminal sequence

Sommer¹,

Nguyen²,

Wang³

1994

FEBS Letters

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Import of proteins into the glycosomes of 7Y brucei resembles the peroxisomal protein import in that C-terminal SKL-like tripeptide sequences can function as targeting signals. Many of the glycosomal proteins do not, however, possess such C-terminal tripeptide signals. Among these, phosphoenolpyruvate carboxykinase (PEPCK (ATP)) was thought to be targeted to the glycosomes by an N-terminal or an internal targeting signal. A limited similarity to the N-terminal targeting signal of rat peroxisomal thiolase exists at the N-terminus of 7: brucei PEPCK. However, we found that this peroxisomal targeting signal does not function for glycosomal protein import in Z brucei. Further studies of the PEPCK gene revealed that the C-terminus of the predicted protein does not correspond to the previously deduced protein sequence of 472 amino acids due to a -1 frame shift error in the original DNA sequence. Readjusting the reading frame of the sequence results in a predicted protein of 525 amino acids in length ending in a tripeptide serine-arginine-leucine (SRL), which is a potential targeting signal for import into the glycosomes. A fusion protein of firefly luciferase, without its own C-terminal SKL targeting signal, and 7: brucei PEPCK is efficiently imported into the glycosomes when expressed in procyclic trypanosomes. Deletion of the C-terminal SRL tripeptide or the last 29 amino acids of PEPCK reduced the import only by about 50% while a deletion of the last 47 amino acids completely abolished the import. These results suggest that 7: brucei PEPCK may contain a second, internal glycosomal targeting signal upstream of the C-terminal SRL sequence.

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“…Maximal import was seen with a construct bearing the first 18 amino acids of aldolase, joined to the CAT initiator methionine via a four amino acid bridge (SSGT) of the same sequence as that used in the thiolase constructs (pHD457). Import of this protein, with about 30%, was at a level similar to that observed using a minimal C-terminal tripeptide signal from trypanosomal phosphoglycerate kinase, -SSL [16]. Inclusion of either more (pAldE, pHD436, pHD456) or fewer aldolase residues (pHD438, pHD442) clearly diminished import.…”

Section: Function Of the Pts-2 In Glycosomal Targetingmentioning

confidence: 62%

“…The presence of PTS-1-type signals has previously been demonstrated on many glycosomal proteins, although the spectrum of tolerated amino acid substitutions appears to be rather enlarged in comparison to other 'higher' eukaryotes [15,16]. As trypanosomatids are evolutionarily the earliest-branching eukaryotes to contain microbodies [17], it is of considerable interest to determine to what extent the import apparatus is conserved.…”

Section: **Present Address: Deutsches Krebsforschungszentrum Immentioning

confidence: 99%

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Function of N‐terminal import signals in trypanosome microbodies

1995

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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.

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Glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a COOH-terminal microbody targeting signal.

Abstract: Abstract. Trypanosomes compartmentalize most of

Cited by 114 publications

References 42 publications

Purification and Partial Characterization of Trypanosoma cruzi Triosephosphate Isomerase

Purification and Partial Characterization of Trypanosoma cruzi Triosephosphate Isomerase

Phosphoenolpyruvate carboxykinase of Trypanosoma brucei is targeted to the glycosomes by a C‐terminal sequence

Function of N‐terminal import signals in trypanosome microbodies

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