maf1 mutation alters the subcellular localization of the Mod5 protein in yeast.

Two forms of Mod5p, a tRNA modification enzyme, are found in three intracellular compartments, mitochondria, cytoplasm and nucleus, but are encoded by a single MOD5 gene. The two forms of the enzyme, Mod5p-I and Mod5p-II differ at the N-termini and are produced by initiation of translation at different start codons. Mod5p-I does contain a mitochondrial targeting signal and is distributed between mitochondria and cytoplasm, whereas Mod5p-II is found in the cytosol and nucleus (Boguta, M., et al. 1994, Mol. Cell. Biol. 14, 2298-2306). In the present work mutants which mislocalize the Mod5p-I enzyme were isolated. The screen was based on a correlation between the amount of cytosolic protein and the efficiency of tRNA mediated suppression. Identification of mutants is possible because a red pigment accumulates in the cells unable to suppress an ade2-1 nonsense allele. The maf1 mutant, with an altered intracellular localization of the Mod5p-I protein, was isolated. Immunofluorescence data suggest that the mutation causes mislocalization of the Mod5p-I to the nucleus.

Download Full-text

Expression and Differential Intracellular Localization of Two Major Forms of Human 8-Oxoguanine DNA Glycosylase Encoded by Alternatively Spliced OGG1 mRNAs

Molecular Biology of the Cell ◽

10.1091/mbc.10.5.1637 ◽

1999 ◽

Vol 10 (5) ◽

pp. 1637-1652 ◽

Cited By ~ 264

Author(s):

Kenichi Nishioka ◽

Toshio Ohtsubo ◽

Hisanobu Oda ◽

Toshiyuki Fujiwara ◽

Dongchon Kang ◽

...

Keyword(s):

Intracellular Localization ◽

Nuclear Extract ◽

Dna Glycosylase ◽

Mitochondrial Targeting ◽

Electron Microscopic ◽

C Terminus ◽

Alternatively Spliced ◽

Targeting Signal ◽

Processed Form

We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types 1a and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1–1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1–1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1–2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1–2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1–2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1–1a depends on the NLS at its C terminus.

Download Full-text

A cytosolic protein contains a cryptic mitochondrial targeting signal

Nature ◽

10.1038/325499a0 ◽

1987 ◽

Vol 325 (6104) ◽

pp. 499-503 ◽

Cited By ~ 67

Author(s):

Eduard C. Hurt ◽

Gottfried Schatz

Keyword(s):

Mitochondrial Targeting ◽

Cytosolic Protein ◽

Targeting Signal

Download Full-text

Identification and Characterization of a Mitochondrial Targeting Signal in Rat Cytochrome P450 2E1 (CYP2E1)

Journal of Biological Chemistry ◽

10.1074/jbc.m008640200 ◽

2000 ◽

Vol 276 (14) ◽

pp. 11317-11322 ◽

Cited By ~ 37

Author(s):

Etienne P. A. Neve ◽

Magnus Ingelman-Sundberg

Keyword(s):

Cytochrome P450 ◽

Cytochrome P450 2E1 ◽

Mitochondrial Targeting ◽

Targeting Signal ◽

Identification And Characterization

Download Full-text

Abstract 2370: Tumor suppression potential of tRNA modification enzyme TruBs via let-7

10.1158/1538-7445.am2021-2370 ◽

2021 ◽

Author(s):

Ryota Kurimoto ◽

Hiroki Tsutsumi ◽

Saki Ikeuchi ◽

Hiroshi Asahara

Keyword(s):

Tumor Suppression ◽

Trna Modification ◽

Modification Enzyme

Download Full-text

Mitochondrial Targeting Signal-Induced Conformational Change and Repression of the Peroxisomal Targeting Signal of the Precursor for Rat Liver Serine: Pyruvate/Alanine: Glyoxylate Aminotransferase

The Journal of Biochemistry ◽

10.1093/oxfordjournals.jbchem.a022655 ◽

2000 ◽

Vol 127 (4) ◽

pp. 665-671 ◽

Cited By ~ 7

Author(s):

T. Oda ◽

C. Uchida ◽

S. Miurat

Keyword(s):

Conformational Change ◽

Rat Liver ◽

Mitochondrial Targeting ◽

Peroxisomal Targeting ◽

Targeting Signal ◽

Glyoxylate Aminotransferase ◽

Peroxisomal Targeting Signal

Download Full-text

Caspase-Dependent Apoptosis Induction via Viral Protein ORF4 of Porcine Circovirus 2 Binding to Mitochondrial Adenine Nucleotide Translocase 3

Journal of Virology ◽

10.1128/jvi.00238-18 ◽

2018 ◽

Vol 92 (10) ◽

Cited By ~ 15

Author(s):

Cui Lin ◽

Jinyan Gu ◽

Huijuan Wang ◽

Jianwei Zhou ◽

Jiarong Li ◽

...

Keyword(s):

Viral Protein ◽

Adenine Nucleotide ◽

Porcine Circovirus Type ◽

Life Cycles ◽

Porcine Circovirus ◽

Mitochondrial Targeting ◽

Orf4 Protein ◽

Targeting Signal ◽

Apoptotic Induction

ABSTRACTApoptosis is an essential strategy of host defense responses and is used by viruses to maintain their life cycles. However, the apoptotic signals involved in virus replication are poorly known. In the present study, we report the molecular mechanism of apoptotic induction by the viral protein ORF4, a newly identified viral protein of porcine circovirus type 2 (PCV2). Apoptosis detection revealed not only that the activity of caspase-3 and -9 is increased in PCV2-infected and ORF4-transfected cells but also that cytochromecrelease from the mitochondria to the cytosol is upregulated. Subsequently, ORF4 protein colocalization with adenine nucleotide translocase 3 (ANT3) was observed using structured illumination microscopy. Moreover, coimmunoprecipitation and pulldown analyses confirmed that the ORF4 protein interacts directly with mitochondrial ANT3 (mtANT3). Binding domain analysis further confirmed that N-terminal residues 1 to 30 of the ORF4 protein, comprising a mitochondrial targeting signal, are essential for the interaction with ANT3. Knockdown ofANT3markedly inhibited the apoptotic induction of both ORF4 protein and PCV2, indicating that ANT3 plays an important role in ORF4 protein-induced apoptosis during PCV2 infection. Taken together, these data indicate that the ORF4 protein is a mitochondrial targeting protein that induces apoptosis by interacting with ANT3 through the mitochondrial pathway.IMPORTANCEThe porcine circovirus type 2 (PCV2) protein ORF4 is a newly identified viral protein; however, little is known about its functions. Apoptosis is an essential strategy of the host defense response and is used by viruses to maintain their life cycles. In the present study, we report the molecular mechanism of the apoptosis induced by the ORF4 protein. The ORF4 protein contains a mitochondrial targeting signal and is an unstable protein that is degraded by the proteasome-dependent pathway. Viral protein ORF4 triggers caspase-3- and -9-dependent cellular apoptosis in mitochondria by directly binding to ANT3. We conclude that the ORF4 protein is a mitochondrial targeting protein and reveal a mechanism whereby circovirus recruits ANT3 to induce apoptosis.

Download Full-text

Evolutionary aspects of a unique internal mitochondrial targeting signal in nuclear-migrated rps19 of sugar beet (Beta vulgaris L.)

Gene ◽

10.1016/j.gene.2012.12.099 ◽

2013 ◽

Vol 517 (1) ◽

pp. 19-26

Author(s):

Muneyuki Matsunaga ◽

Yoshiya Takahashi ◽

Rika Yui-Kurino ◽

Tetsuo Mikami ◽

Tomohiko Kubo

Keyword(s):

Sugar Beet ◽

Beta Vulgaris ◽

Mitochondrial Targeting ◽

Targeting Signal ◽

Evolutionary Aspects

Download Full-text

A conserved late endosome–targeting signal required for Doa4 deubiquitylating enzyme function

The Journal of Cell Biology ◽

10.1083/jcb.200605134 ◽

2006 ◽

Vol 175 (5) ◽

pp. 825-835 ◽

Cited By ~ 34

Author(s):

Alexander Amerik ◽

Nazia Sindhi ◽

Mark Hochstrasser

Keyword(s):

Subcellular Localization ◽

Terminal Segment ◽

Late Endosome ◽

Enzyme Specificity ◽

Endosomal Sorting ◽

Terminal Domain ◽

Localization Signal ◽

Targeting Signal ◽

Processing Protease

Enzyme specificity in vivo is often controlled by subcellular localization. Yeast Doa4, a deubiquitylating enzyme (DUB), removes ubiquitin from membrane proteins destined for vacuolar degradation. Doa4 is recruited to the late endosome after ESCRT-III (endosomal sorting complex required for transport III) has assembled there. We show that an N-terminal segment of Doa4 is sufficient for endosome association. This domain bears four conserved elements (boxes A–D). Deletion of the most conserved of these, A or B, prevents Doa4 endosomal localization. These mutants cannot sustain ubiquitin-dependent proteolysis even though neither motif is essential for deubiquitylating activity. Ubiquitin-specific processing protease 5 (Ubp5), the closest paralogue of Doa4, has no functional overlap. Ubp5 concentrates at the bud neck; its N-terminal domain is critical for this. Importantly, substitution of the Ubp5 N-terminal domain with that of Doa4 relocalizes the Ubp5 enzyme to endosomes and provides Doa4 function. This is the first demonstration of a physiologically important DUB subcellular localization signal and provides a striking example of the functional diversification of DUB paralogues by the evolution of alternative spatial signals.

Download Full-text