scholarly journals The kinetoplastid-specific phosphatase KPP1 attenuates PLK activity to facilitate flagellum inheritance in Trypanosoma brucei

2021 ◽  
Vol 14 (669) ◽  
pp. eabc6435
Author(s):  
Tai An ◽  
Huiqing Hu ◽  
Ziyin Li
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Protein Phosphatase ◽  
Catalytic Domain ◽  
Complex Structure ◽  
Cell Communication ◽  
Specific Protein ◽  
Activation Loop ◽  
Human Parasite ◽  
Complex Protein

Trypanosoma brucei, an important human parasite, has a flagellum that controls cell motility, morphogenesis, proliferation, and cell-cell communication. Inheritance of the newly assembled flagellum during the cell cycle requires the Polo-like kinase homolog TbPLK and the kinetoplastid-specific protein phosphatase KPP1, although whether TbPLK acts on KPP1 or vice versa has been unclear. Here, we showed that dephosphorylation of TbPLK on Thr125 by KPP1 maintained low TbPLK activity in the flagellum-associated hook complex structure, thereby ensuring proper flagellum positioning and attachment. This dephosphorylation event required the recognition of phosphorylated Thr198 in the activation loop of TbPLK by the N-terminal Plus3 domain of KPP1 and the dephosphorylation of phosphorylated Thr125 in TbPLK by the C-terminal catalytic domain of KPP1. Dephosphorylation of TbPLK by KPP1 prevented hyperphosphorylation of the hook complex protein TbCentrin2, thereby allowing timely dephosphorylation of phosphorylated TbCentrin2 for hook complex duplication and flagellum positioning and attachment. Thus, KPP1 attenuates TbPLK activity by dephosphorylating TbPLK to facilitate flagellum inheritance.

The SIT4 protein phosphatase functions in late G1 for progression into S phase

1991 ◽  
Vol 11 (4) ◽  
pp. 2133-2148
Author(s):  
A Sutton ◽  
D Immanuel ◽  
K T Arndt
Keyword(s):  
Cell Cycle ◽  
Protein Phosphatase ◽  
Catalytic Domain ◽  
Function Analysis ◽  
S Phase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Amino Terminal ◽  
Polymorphic Gene ◽  
Cycle Dependent

Saccharomyces cerevisiae strains containing temperature-sensitive mutations in the SIT4 protein phosphatase arrest in late G1 at the nonpermissive temperature. Order-of-function analysis shows that SIT4 is required in late G1 for progression into S phase. While the levels of SIT4 do not change in the cell cycle, SIT4 associates with two high-molecular-weight phosphoproteins in a cell-cycle-dependent fashion. In addition, we have identified a polymorphic gene, SSD1, that in some versions can suppress the lethality due to a deletion of SIT4 and can also partially suppress the phenotypic defects due to a null mutation in BCY1. The SSD1 protein is implicated in G1 control and has a region of similarity to the dis3 protein of Schizosaccharomyces pombe. We have also identified a gene, PPH2alpha, that in high copy number can partially suppress the growth defect of sit4 strains. The PPH2 alpha gene encodes a predicted protein that is 80% identical to the catalytic domain of mammalian type 2A protein phosphatases but also has an acidic amino-terminal extension not present in other phosphatases.

scholarly journals Regulated protein stabilization underpins the functional interplay among basal body components in Trypanosoma brucei

2019 ◽  
Vol 295 (3) ◽  
pp. 729-742
Author(s):  
Kieu T. M. Pham ◽  
Ziyin Li
Keyword(s):  
Trypanosoma Brucei ◽  
Basal Body ◽  
Super Resolution ◽  
Specific Protein ◽  
Protein Stabilization ◽  
Structured Illumination ◽  
Human Parasite ◽  
Evolutionarily Conserved ◽  
Body Components ◽  
Super Resolution Microscopy

The basal body in the human parasite Trypanosoma brucei is structurally equivalent to the centriole in animals and functions in the nucleation of axonemal microtubules in the flagellum. T. brucei lacks many evolutionarily conserved centriolar protein homologs and constructs the basal body through unknown mechanisms. Two evolutionarily conserved centriole/basal body cartwheel proteins, TbSAS-6 and TbBLD10, and a trypanosome-specific protein, BBP65, play essential roles in basal body biogenesis in T. brucei, but how they cooperate in the regulation of basal body assembly remains elusive. Here using RNAi, endogenous epitope tagging, immunofluorescence microscopy, and 3D-structured illumination super-resolution microscopy, we identified a new trypanosome-specific protein named BBP164 and found that it has an essential role in basal body biogenesis in T. brucei. Further investigation of the functional interplay among BBP164 and the other three regulators of basal body assembly revealed that BBP164 and BBP65 are interdependent for maintaining their stability and depend on TbSAS-6 and TbBLD10 for their stabilization in the basal body. Additionally, TbSAS-6 and TbBLD10 are independent from each other and from BBP164 and BBP65 for maintaining their stability in the basal body. These findings demonstrate that basal body cartwheel proteins are required for stabilizing other basal body components and uncover that regulation of protein stability is an unusual control mechanism for assembly of the basal body in T. brucei.

Identification of a protein phosphatase 2A family member that regulates cell cycle progression in Trypanosoma brucei

2014 ◽  
Vol 194 (1-2) ◽  
pp. 48-52 ◽  
Author(s):  
Karen G. Rothberg ◽  
Neal Jetton ◽  
James G. Hubbard ◽  
Daniel A. Powell ◽  
Vidya Pandarinath ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Family Member ◽  
Trypanosoma Brucei ◽  
Protein Phosphatase ◽  
Cell Cycle Progression ◽  
Protein Phosphatase 2A ◽  
Cycle Progression ◽  
Phosphatase 2A

scholarly journals The SIT4 protein phosphatase functions in late G1 for progression into S phase.

1991 ◽  
Vol 11 (4) ◽  
pp. 2133-2148 ◽  
Author(s):  
A Sutton ◽  
D Immanuel ◽  
K T Arndt
Keyword(s):  
Cell Cycle ◽  
Protein Phosphatase ◽  
Catalytic Domain ◽  
Function Analysis ◽  
S Phase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Amino Terminal ◽  
Polymorphic Gene ◽  
Cycle Dependent

Saccharomyces cerevisiae strains containing temperature-sensitive mutations in the SIT4 protein phosphatase arrest in late G1 at the nonpermissive temperature. Order-of-function analysis shows that SIT4 is required in late G1 for progression into S phase. While the levels of SIT4 do not change in the cell cycle, SIT4 associates with two high-molecular-weight phosphoproteins in a cell-cycle-dependent fashion. In addition, we have identified a polymorphic gene, SSD1, that in some versions can suppress the lethality due to a deletion of SIT4 and can also partially suppress the phenotypic defects due to a null mutation in BCY1. The SSD1 protein is implicated in G1 control and has a region of similarity to the dis3 protein of Schizosaccharomyces pombe. We have also identified a gene, PPH2alpha, that in high copy number can partially suppress the growth defect of sit4 strains. The PPH2 alpha gene encodes a predicted protein that is 80% identical to the catalytic domain of mammalian type 2A protein phosphatases but also has an acidic amino-terminal extension not present in other phosphatases.

scholarly journals Role for protein phosphatases in the cell-cycle-regulated phosphorylation of stathmin

1998 ◽  
Vol 334 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Sucharita J. MISTRY ◽  
Heng-Chun LI ◽  
George F. ATWEH
Keyword(s):  
Cell Cycle ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Protein Phosphatases ◽  
Specific Protein ◽  
G1 Phase ◽  
Major Increase ◽  
Protein Phosphatase Type

Stathmin is a major cytosolic phosphoprotein that regulates microtubule dynamics during the assembly of the mitotic spindle. The activity of stathmin itself is regulated by changes in its state of phosphorylation during the transition from interphase to metaphase. For a better understanding of the regulation of stathmin activity during the cell cycle, we explored the mechanism(s) responsible for the decrease in the level of phosphorylation of stathmin as cells complete mitosis and enter a new G1 phase. We show that stathmin mRNA and protein are expressed constitutively throughout the different phases of the cell cycle. This suggests that the non-phosphorylated stathmin that predominates during G1 is not generated by degradation of phosphorylated stathmin in mitosis and synthesis of new unphosphorylated stathmin as cells enter a new G1 phase. This suggested that protein phosphatases might be responsible for dephosphorylating stathmin as cells enter a new cell cycle. Okadaic acid-mediated inhibition of protein phosphatases in vivoshowed a major increase in the level of phosphorylation of stathmin. Dephosphorylation studies in vitro showed differential patterns of site-specific dephosphorylaton of stathmin to protein phosphatase type 1, protein phosphatase type 2A and protein phosphatase type 2B. Thus stathmin might be a target for okadaic acid-sensitive protein phosphatase(s), and its activity in eukaryotic cells might be modulated by the sequential activity of specific protein kinases and phosphatases.

scholarly journals MicroRNA-527 Induces Proliferation and Cell Cycle in Esophageal Squamous Cell Carcinoma Cells by Repressing PH Domain Leucine-Rich-Repeats Protein Phosphatase 2

Dose-Response ◽  
2020 ◽  
Vol 18 (2) ◽  
pp. 155932582092868 ◽  
Author(s):  
Qingjie Xian ◽  
Ronglei Zhao ◽  
Juanjuan Fu
Keyword(s):  
Cell Cycle ◽  
Squamous Cell Carcinoma ◽  
Esophageal Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Cancer Progression ◽  
Squamous Cell ◽  
Protein Phosphatase ◽  
Ph Domain ◽  
Gene Reporter Assay ◽  
Protein Phosphatase 2

Increasing evidence indicated that microRNAs served dominant roles in carcinogenesis and cancer progression by targeting potential downstream genes. In our study, we found that miR-527 was an upregulated expression in human esophageal squamous cell carcinoma (ESCC) cells and tissues. Furthermore, overexpression of miR-527 promoted cell proliferation and colony formation, enhanced anchorage-independent growth ability, and contributed to cell cycle. In addition, protein phosphatase 2 (PHLPP2) was identified as the direct downstream target gene of miR-527 and was confirmed by luciferase gene reporter assay. In summary, we concluded that miR-527 acted as an oncogenic microRNA in ESCC development by directly targeting PHLPP2 might be a novel therapeutic target for the treatment of ESCC.

scholarly journals The Negative Effect of Protein Phosphatase Z1 Deletion on the Oxidative Stress Tolerance of Candida albicans Is Synergistic with Betamethasone Exposure

2021 ◽  
Vol 7 (7) ◽  
pp. 540
Author(s):  
Ágnes Jakab ◽  
Tamás Emri ◽  
Kinga Csillag ◽  
Anita Szabó ◽  
Fruzsina Nagy ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Candida Albicans ◽  
Protein Phosphatase ◽  
Combined Treatment ◽  
Specific Protein ◽  
Ergosterol Biosynthesis ◽  
Acid Oxidation ◽  
Menadione Sodium Bisulfite ◽  
Rnaseq Data ◽  
Negative Effect

The glucocorticoid betamethasone (BM) has potent anti-inflammatory and immunosuppressive effects; however, it increases the susceptibility of patients to superficial Candida infections. Previously we found that this disadvantageous side effect can be counteracted by menadione sodium bisulfite (MSB) induced oxidative stress treatment. The fungus specific protein phosphatase Z1 (CaPpz1) has a pivotal role in oxidative stress response of Candida albicans and was proposed as a potential antifungal drug target. The aim of this study was to investigate the combined effects of CaPPZ1 gene deletion and MSB treatment in BM pre-treated C. albicans cultures. We found that the combined treatment increased redox imbalance, enhanced the specific activities of antioxidant enzymes, and reduced the growth in cappz1 mutant (KO) strain. RNASeq data demonstrated that the presence of BM markedly elevated the number of differentially expressed genes in the MSB treated KO cultures. Accumulation of reactive oxygen species, increased iron content and fatty acid oxidation, as well as the inhibiting ergosterol biosynthesis and RNA metabolic processes explain, at least in part, the fungistatic effect caused by the combined stress exposure. We suggest that the synergism between MSB treatment and CaPpz1 inhibition could be considered in developing of a novel combinatorial antifungal strategy accompanying steroid therapy.

scholarly journals Identification of a serine/threonine-specific protein phosphatase from the archaebacterium Sulfolobus solfataricus.

1993 ◽  
Vol 268 (9) ◽  
pp. 6505-6510
Author(s):  
P.J. Kennelly ◽  
K.A. Oxenrider ◽  
J. Leng ◽  
J.S. Cantwell ◽  
N. Zhao
Keyword(s):  
Protein Phosphatase ◽  
Sulfolobus Solfataricus ◽  
Specific Protein

scholarly journals Polo-like kinase is required for Golgi and bilobe biogenesis in Trypanosoma brucei

2008 ◽  
Vol 181 (3) ◽  
pp. 431-438 ◽  
Author(s):  
Christopher L. de Graffenried ◽  
Helen H. Ho ◽  
Graham Warren
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Trypanosoma Brucei ◽  
Protozoan Parasite ◽  
Controlled Assembly

A bilobed structure marked by TbCentrin2 regulates Golgi duplication in the protozoan parasite Trypanosoma brucei. This structure must itself duplicate during the cell cycle for Golgi inheritance to proceed normally. We show here that duplication of the bilobed structure is dependent on the single polo-like kinase (PLK) homologue in T. brucei (TbPLK). Depletion of TbPLK leads to malformed bilobed structures, which is consistent with an inhibition of duplication and an increase in the number of dispersed Golgi structures with associated endoplasmic reticulum exit sites. These data suggest that the bilobe may act as a scaffold for the controlled assembly of the duplicating Golgi.

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