Atypical caseinolytic protease homolog from Plasmodium falciparum possesses unusual substrate preference and a functional nuclear localization signal

2009 ◽  
Vol 105 (6) ◽  
pp. 1715-1722 ◽  
Author(s):  
Wenjie Lin ◽  
Maurice Chan ◽  
Tiow-Suan Sim
Keyword(s):  
Plasmodium Falciparum ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Substrate Preference ◽  
Caseinolytic Protease ◽  
Localization Signal ◽  
Functional Nuclear Localization Signal

scholarly journals Identification of a nuclear localization signal in the Plasmodium falciparum CTP: phosphocholine cytidylyltransferase enzyme

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Richard Izrael ◽  
Lívia Marton ◽  
Gergely N. Nagy ◽  
Hajnalka L. Pálinkás ◽  
Nóra Kucsma ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Cell Line ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Membrane Binding ◽  
Binding Domain ◽  
Regulatory Function ◽  
Phosphocholine Cytidylyltransferase ◽  
Phosphatidylcholine Biosynthesis ◽  
Localization Signal

AbstractThe phospholipid biosynthesis of the malaria parasite, Plasmodium falciparum is a key process for its survival and its inhibition is a validated antimalarial therapeutic approach. The second and rate-limiting step of the de novo phosphatidylcholine biosynthesis is catalysed by CTP: phosphocholine cytidylyltransferase (PfCCT), which has a key regulatory function within the pathway. Here, we investigate the functional impact of the key structural differences and their respective role in the structurally unique pseudo-heterodimer PfCCT protein in a heterologous cellular context using the thermosensitive CCT-mutant CHO-MT58 cell line. We found that a Plasmodium-specific lysine-rich insertion within the catalytic domain of PfCCT acts as a nuclear localization signal and its deletion decreases the nuclear propensity of the protein in the model cell line. We further showed that the putative membrane-binding domain also affected the nuclear localization of the protein. Moreover, activation of phosphatidylcholine biosynthesis by phospholipase C treatment induces the partial nuclear-to-cytoplasmic translocation of PfCCT. We additionally investigated the cellular function of several PfCCT truncated constructs in a CHO-MT58 based rescue assay. In absence of the endogenous CCT activity we observed that truncated constructs lacking the lysine-rich insertion, or the membrane-binding domain provided similar cell survival ratio as the full length PfCCT protein.

scholarly journals SUMOylation of the Polyglutamine Repeat Protein, Ataxin-1, Is Dependent on a Functional Nuclear Localization Signal

2005 ◽  
Vol 280 (23) ◽  
pp. 21942-21948 ◽  
Author(s):  
Brigit E. Riley ◽  
Huda Y. Zoghbi ◽  
Harry T. Orr
Keyword(s):  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
High Mobility ◽  
Wild Type ◽  
Repeat Protein ◽  
Polyglutamine Repeat ◽  
Lysine Residues ◽  
Localization Signal ◽  
Functional Nuclear Localization Signal ◽  
Polyglutamine Tract

SUMO (small ubiquitin-like modifier) is a member of the ubiquitin family of proteins. SUMO targets include proteins involved in numerous roles including nuclear transport and transcriptional regulation. The previous finding that mutant ataxin-1[82Q] disrupted promyelocytic leukemia (PML) oncogenic domains prompted us to determine whether ataxin-1 disrupts another component of PML oncogenic domains, Sp100 (100-kDa Speckled protein). Similar to the PML protein, mutant ataxin-1[82Q] redistributed Sp100 to mutant ataxin-1[82Q] nuclear inclusions. Based on the ability of PML and Sp100 to be covalently modified by SUMO, we investigated the ability of ataxin-1 to be SUMOylated. SUMO-1 was found to covalently modify the polyglutamine repeat protein ataxin-1. There was a decrease in ataxin-1 SUMOylation in the presence of the expanded polyglutamine tract, ataxin-1[82Q]. The phospho-mutant, ataxin-1[82Q]-S776A, restored SUMO levels to those of wild-type ataxin-1[30Q]. SUMOylation of ataxin-1 was dependent on a functional nuclear localization signal. Ataxin-1 SUMOylation was mapped to at least five lysine residues. Lys16, Lys194 preceding the polyglutamine tract, Lys610/Lys697 in the C-terminal ataxin high mobility group domain, and Lys746 all contribute to ataxin-1 SUMOylation.

scholarly journals The C2A Domain of Double C2 Protein γ Contains a Functional Nuclear Localization Signal

2001 ◽  
Vol 276 (27) ◽  
pp. 24441-24444 ◽  
Author(s):  
Mitsunori Fukuda ◽  
Chika Saegusa ◽  
Eiko Kanno ◽  
Katsuhiko Mikoshiba
Keyword(s):  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Localization Signal ◽  
Functional Nuclear Localization Signal ◽  
C2a Domain

scholarly journals Karyopherin α-2 Mediates MDC1 Nuclear Import through a Functional Nuclear Localization Signal in the tBRCT Domain of MDC1

2020 ◽  
Vol 21 (7) ◽  
pp. 2650
Author(s):  
Kamalakannan Radhakrishnan ◽  
Seon-Joo Park ◽  
Seok Won Kim ◽  
Gurusamy Hariharasudhan ◽  
Seo-Yeon Jeong ◽  
...  
Keyword(s):  
Dna Damage ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Ring Finger ◽  
Nucleocytoplasmic Transport ◽  
Ring Finger Protein ◽  
Finger Protein ◽  
Localization Signal ◽  
Functional Nuclear Localization Signal

Mediator of DNA damage checkpoint protein 1 (MDC1) plays a vital role in DNA damage response (DDR) by coordinating the repair of double strand breaks (DSBs). Here, we identified a novel interaction between MDC1 and karyopherin α-2 (KPNA2), a nucleocytoplasmic transport adaptor, and showed that KPNA2 is necessary for MDC1 nuclear import. Thereafter, we identified a functional nuclear localization signal (NLS) between amino acid residues 1989–1994 of the two Breast Cancer 1 (BRCA1) carboxyl-terminal (tBRCT) domain of MDC1 and demonstrated disruption of this NLS impaired interaction between MDC1 and KPNA2 and reduced nuclear localization of MDC1. In KPNA2-depleted cells, the recruitment of MDC1, along with the downstream signaling p roteins Ring Finger Protein 8 (RNF8), 53BP1-binding protein 1 (53BP1), BRCA1, and Ring Finger Protein 168 (RNF168), to DNA damage sites was abolished. Additionally, KPNA2-depleted cells had a decreased rate of homologous recombination (HR) repair. Our data suggest that KPNA2-mediated MDC1 nuclear import is important for DDR signaling and DSB repair.

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