The Crithidia fasciculata RNH1 gene encodes both nuclear and mitochondrial isoforms of RNase H

Engel, Michele L.

doi:10.1093/nar/29.3.725

Cited by 19 publications

(10 citation statements)

References 49 publications

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“…A proline racemase from T. cruzi is secreted (long transcript) or cytosolic (short transcript) (Chamond et al ., 2003). In Crithidia fasciculata the translation product of the largest transcript from the RNH gene is located inside the mitochondrion, while the product encoded by the short transcript is targeted to the nucleus (Engel et al ., 2001).…”

Section: Discussionmentioning

confidence: 99%

Alternative trans‐splicing of the Trypanosoma cruzi LYT1 gene transcript results in compartmental and functional switch for the encoded protein

Benabdellah

González‐Rey

González³

2007

Molecular Microbiology

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SummaryTrypanosma cruzi has a complex life cycle that includes infective and non-infective stages in distinct hosts. Control of gene expression by the parasite must adjust to rather diverse circumstances. Through stage-regulated, alternative trans-splicing of the primary transcript, the T. cruzi LYT1 gene generates two protein products differing in the presence or absence of 28 amino acids at their amino end. We find that the shorter protein, kLYT1, is located at two spots in the mitochondrial kinetoflagellar zone and its expression reverts the 'accelerated stage development' phenotype of the LYT1-null mutant. The larger product, mLYT1, localizes on the plasma membrane. The signal for membrane localization presents characteristics of a type II anchor including the possibility of cleavage. Expression of mLYT1 reverts the 'loss of virulence' phenotype associated to diminished haemolytic activity at acid pH, but stage development still progresses at an accelerated rate. This compartmentalization switch of LYT1 results in two surprisingly different functions: haemolytic activity at acid pH for mLYT1, and a putative involvement in mitochondrial metabolism for kLYT1. We conclude that alternative trans-splicing plays an important role in stage-regulated control of gene expression in trypanosomatids.

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Section: Discussionmentioning

confidence: 99%

Alternative trans‐splicing of the Trypanosoma cruzi LYT1 gene transcript results in compartmental and functional switch for the encoded protein

Benabdellah

González‐Rey

González³

2007

Molecular Microbiology

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“…Several of the proteins involved in the replication of the kDNA network have been identified, including the origin-binding protein, designated the UMS-binding protein (UMSBP) (2-4, 61, 62), DNA polymerases (23,(57)(58)(59), primase (30), topoisomerase II (31,32), structure-specific endonuclease 1 (SSE1) (13,14), RNase H (9,12,42), RNA polymerase (20), and structural proteins (73,74). UMSBP has been purified from C. fasciculata, and its encoding gene and genomic locus have been cloned and analyzed (2,(61)(62)(63).…”

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confidence: 99%

Redox Potential Regulates Binding of Universal Minicircle Sequence Binding Protein at the Kinetoplast DNA Replication Origin

Onn

Milman-Shtepel²,

Shlomai³

2004

Eukaryot Cell

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Kinetoplast DNA, the mitochondrial DNA of the trypanosomatid Crithidia fasciculata, is a remarkable structure containing 5,000 topologically linked DNA minicircles. Their replication is initiated at two conserved sequences, a dodecamer, known as the universal minicircle sequence (UMS), and a hexamer, which are located at the replication origins of the minicircle L- and H-strands, respectively. A UMS-binding protein (UMSBP), binds specifically the conserved origin sequences in their single stranded conformation. The five CCHC-type zinc knuckle motifs, predicted in UMSBP, fold into zinc-dependent structures capable of binding a single-stranded nucleic acid ligand. Zinc knuckles that are involved in the binding of DNA differ from those mediating protein-protein interactions that lead to the dimerization of UMSBP. Both UMSBP DNA binding and its dimerization are sensitive to redox potential. Oxidation of UMSBP results in the protein dimerization, mediated through its N-terminal domain, with a concomitant inhibition of its DNA-binding activity. UMSBP reduction yields monomers that are active in the binding of DNA through the protein C-terminal region. C. fasciculata trypanothione-dependent tryparedoxin activates the binding of UMSBP to UMS DNA in vitro. The possibility that UMSBP binding at the minicircle replication origin is regulated in vivo by a redox potential-based mechanism is discussed.

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“…Alteration of the N‐terminal portion contributes to the subcellular localization of RNase H1 in the mouse [21] and Cr. fasciculata [34], and protein diversity in these cases may be caused by translation from different start codons. In C. elegans , phylogenetic profiling of eukaryotic proteins has also determined that there are ≈660 nucleus‐encoded mitochondrial genes, and C. elegans RNase H1 enzymes are also predicted to be mitochondrial [35].…”

Section: Resultsmentioning

confidence: 99%

Stage‐specific expression of Caenorhabditis elegans ribonuclease H1 enzymes with different substrate specificities and bivalent cation requirements

Kochiwa¹,

Itaya²,

Tomita³

et al. 2005

The FEBS Journal

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An enzyme that specifically degrades the RNA strand of RNA-DNA hybrids was first characterized from extracts of calf thymus tissue [1] and was named ribonuclease H (RNase H; EC 3.1.26.4) [2]. This protein has also been identified in viruses [3], bacteria [4,5], and archaea [6,7], indicating the essential nature of its roles in cellular metabolism. Prokaryotic RNase H enzymes are divided by sequence similarity into three groups: HI, HII, and HIII. On the other hand, there are two types of eukaryotic RNase H: RNase H1 is homologous to prokaryotic RNase HI, and RNase H2 is homologous to prokaryotic RNase HII. There is a distinct difference between the two types of eukaryotic RNase H in terms of the bivalent metal ion cofactor. Ribonuclease H1 (RNase H1) is a widespread enzyme found in a range of organisms from viruses to humans. It is capable of degrading the RNA moiety of DNA-RNA hybrids and requires a bivalent ion for activity. In contrast with most eukaryotes, which have one gene encoding RNase H1, the activity of which depends on Mg 2+ ions, Caenorhabditis elegans has four RNase H1-related genes, and one of them has an isoform produced by alternative splicing. However, little is known about the enzymatic features of the proteins encoded by these genes. To determine the differences between these enzymes, we compared the expression patterns of each RNase H1-related gene throughout the development of the nematode and the RNase H activities of their recombinant proteins. We found gene-specific expression patterns and different enzymatic features. In particular, besides the enzyme that displays the highest activity in the presence of Mg 2+ ions, C. elegans has another enzyme that shows preference for Mn 2+ ion as a cofactor. We characterized this Mn 2+ -dependent RNase H1 for the first time in eukaryotes. These results suggest that there are at least two types of RNase H1 in C. elegans depending on the developmental stage of the organism.Abbreviations dsRHbd, double-stranded RNA and RNA-DNA hybrid-binding domain; Ec-RNHI, Escherichia coli ribonuclease HI; Pf-RNHII, Pyrococcus furiosus ribonuclease HII; PTC, premature termination codon, RNase H, ribonuclease H.

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The Crithidia fasciculata RNH1 gene encodes both nuclear and mitochondrial isoforms of RNase H

Cited by 19 publications

References 49 publications

Alternative trans‐splicing of the Trypanosoma cruzi LYT1 gene transcript results in compartmental and functional switch for the encoded protein

Alternative trans‐splicing of the Trypanosoma cruzi LYT1 gene transcript results in compartmental and functional switch for the encoded protein

Redox Potential Regulates Binding of Universal Minicircle Sequence Binding Protein at the Kinetoplast DNA Replication Origin

Stage‐specific expression of Caenorhabditis elegans ribonuclease H1 enzymes with different substrate specificities and bivalent cation requirements

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