scholarly journals Signal Transduction Protein PII Phosphatase PphA Is Required for Light-Dependent Control of Nitrate Utilization in Synechocystis sp. Strain PCC 6803

2005 ◽  
Vol 187 (19) ◽  
pp. 6683-6690 ◽  
Author(s):  
Nicole Kloft ◽  
Karl Forchhammer
Keyword(s):  
Signal Transduction ◽  
Protein Phosphatase ◽  
Nitrate Uptake ◽  
Photon Flux ◽  
Wild Type ◽  
Low Light ◽  
Signal Transduction Protein ◽  
The Impact ◽  
Reduction Capacity ◽  
Pcc 6803

ABSTRACT Signal transduction protein PII is dephosphorylated in Synechocystis sp. strain PCC 6803 by protein phosphatase PphA. To determine the impact of PphA-mediated PII dephosphorylation on physiology, the phenotype of a PphA-deficient mutant was analyzed. Mutants lacking either PphA or PII were impaired in efficient utilization of nitrate as the nitrogen source. Under conditions of limiting photosystem I (PSI)-reduced ferredoxin, excess reduction of nitrate along with impaired reduction of nitrite occurred in PII signaling mutants, resulting in excretion of nitrite to the medium. This effect could be reversed by increasing the level of PSI-reduced ferredoxin. We present evidence that nonphosphorylated PII controls the utilization of nitrate in response to low light intensity by tuning down nitrate uptake to meet the actual reduction capacity. This control mechanism can be bypassed by exposing cells to excess levels of nitrate. Uncontrolled nitrate uptake leads to light-dependent nitrite excretion even in wild-type cells, confirming that nitrate uptake controls nitrate utilization in response to limiting photon flux densities.

scholarly journals PII-Regulated Arginine Synthesis Controls Accumulation of Cyanophycin in Synechocystis sp. Strain PCC 6803

2006 ◽  
Vol 188 (7) ◽  
pp. 2730-2734 ◽  
Author(s):  
Mani Maheswaran ◽  
Karl Ziegler ◽  
Wolfgang Lockau ◽  
Martin Hagemann ◽  
Karl Forchhammer
Keyword(s):  
Signal Transduction ◽  
Aspartic Acid ◽  
Heterotrophic Bacteria ◽  
Nitrogen Storage ◽  
Arginine Biosynthesis ◽  
Signal Transduction Protein ◽  
Key Enzyme ◽  
Nitrogen Excess ◽  
Synechocystis Sp ◽  
Pcc 6803

ABSTRACT Cyanophycin (multi-l-arginyl-poly-l-aspartic acid) is a nitrogen storage polymer found in most cyanobacteria and some heterotrophic bacteria. The cyanobacterium Synechocystis sp. strain PCC 6803 accumulates cyanophycin following a transition from nitrogen-limited to nitrogen-excess conditions. Here we show that the accumulation of cyanophycin depends on the activation of the key enzyme of arginine biosynthesis, N-acetyl-l-glutamate kinase, by signal transduction protein PII.

Megakaryocyte proliferation and ploidy regulated by the cytoplasmic tail of glycoprotein Ibα

Blood ◽  
2004 ◽  
Vol 104 (10) ◽  
pp. 3161-3168 ◽  
Author(s):  
Taisuke Kanaji ◽  
Susan Russell ◽  
Janet Cunningham ◽  
Kenji Izuhara ◽  
Joan E. B. Fox ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Gene Product ◽  
Cytoplasmic Tail ◽  
Temporal Sequence ◽  
Signaling Proteins ◽  
Wild Type ◽  
Akt Phosphorylation ◽  
Signal Transduction Protein ◽  
Sequence Of Events ◽  
Apoptotic Markers

Abstract We have investigated the ability of glycoprotein (GP) Ibα, a megakaryocytic gene product, to sequester the signal transduction protein 14-3-3ξ and to influence megakaryocytopoiesis. Using a Gp1ba–/– mouse colony, we compared the rescued phenotypes produced by a wild-type human GP Ibα allele or a similar allele containing a 6-residue cytoplasmic tail truncation that abrogates binding to 14-3-3ξ. The observed phenotypes illustrate an involvement for GP Ibα in thrombopoietin-mediated events of megakaryocyte proliferation, polyploidization, and the expression of apoptotic markers in maturing megakaryocytes. We developed a hypothesis for the involvement of a GP Ibα/14-3-3ξ/PI-3 kinase complex in regulating thrombopoietin-mediated responses. An observed increase in thrombopoietin-mediated Akt phosphorylation in the truncated variant supported the hypothesis and led to the development of a model in which the GP Ibα cytoplasmic tail sequestered signaling proteins during megakaryocytopoiesis and, as such, became a critical regulator in the temporal sequence of events that led to normal megakaryocyte maturation.

scholarly journals Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

2010 ◽  
Vol 192 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Francis X. Cunningham ◽  
Ashley B. Tice ◽  
Christina Pham ◽  
Elisabeth Gantt
Keyword(s):  
Inclusion Bodies ◽  
Light Stress ◽  
High Irradiance ◽  
Oxygenic Photosynthesis ◽  
Wild Type ◽  
Fundamental Function ◽  
Low Light ◽  
Photooxidative Damage ◽  
Genes Encoding ◽  
Pcc 6803

ABSTRACT Plastoglobulins (PGL) are the predominant proteins of lipid globules in the plastids of flowering plants. Genes encoding proteins similar to plant PGL are also present in algae and cyanobacteria but in no other organisms, suggesting an important role for these proteins in oxygenic photosynthesis. To gain an understanding of the core and fundamental function of PGL, the two genes that encode PGL-like polypeptides in the cyanobacterium Synechocystis sp. PCC 6803 (pgl1 and pgl2) were inactivated individually and in combination. The resulting mutants were able to grow under photoautotrophic conditions, dividing at rates that were comparable to that of the wild-type (WT) under low-light (LL) conditions (10 microeinsteins·m−2·s−1) but lower than that of the WT under moderately high-irradiance (HL) conditions (150 microeinsteins·m−2·s−1). Under HL, each Δpgl mutant had less chlorophyll, a lower photosystem I (PSI)/PSII ratio, more carotenoid per unit of chlorophyll, and very much more myxoxanthophyll (a carotenoid symptomatic of high light stress) per unit of chlorophyll than the WT. Large, heterogeneous inclusion bodies were observed in cells of mutants inactivated in pgl2 or both pgl2 and pgl1 under both LL and HL conditions. The mutant inactivated in both pgl genes was especially sensitive to the light environment, with alterations in pigmentation, heterogeneous inclusion bodies, and a lower PSI/PSII ratio than the WT even for cultures grown under LL conditions. The WT cultures grown under HL contained 2- to 3-fold more PGL1 and PGL2 per cell than cultures grown under LL conditions. These and other observations led us to conclude that the PGL-like polypeptides of Synechocystis play similar but not identical roles in some process relevant to the repair of photooxidative damage.

scholarly journals Sll1717 Affects the Redox State of the Plastoquinone Pool by Modulating Quinol Oxidase Activity in Thylakoids

2006 ◽  
Vol 188 (4) ◽  
pp. 1286-1294 ◽  
Author(s):  
Galyna I. Kufryk ◽  
Wim F. J. Vermaas
Keyword(s):  
Transcript Level ◽  
Wild Type ◽  
Low Light ◽  
Quinol Oxidase ◽  
Plastoquinone Pool ◽  
Light Intensities ◽  
In The Wild ◽  
Plausible Mechanism ◽  
Selection For ◽  
Pcc 6803

ABSTRACT A Synechocystis sp. strain PCC 6803 mutant lacking CtaI, a main subunit of cytochrome c oxidase, is not capable of growing at light intensities below 5 μmol photons m−2 s−1, presumably due to an overreduced plastoquinone pool in the thylakoid membrane. Upon selection for growth at light intensities below 5 μmol photons m−2 s−1, a secondary mutant was generated that retained the CtaI deletion and had fully assembled photosystem II complexes; in this secondary mutant (pseudorevertant), oxygen evolution and respiratory activities were similar to those in the wild type. Functional complementation of the original CtaI-less strain to low-light tolerance by transformation with restriction fragments of genomic DNA of the pseudorevertant and subsequent mapping of the pseudoreversion site showed that the point mutation led to a Ser186Cys substitution in Sll1717, a protein of as-yet-unknown function and with a predicted ATP/GTP-binding domain. This mutation caused a decrease in the plastoquinone pool reduction level of thylakoids compared to that observed for the wild type. Based on a variety of experimental evidence, the most plausible mechanism to cause this effect is an activation of plastoquinol oxidation in thylakoids by the quinol oxidase CydAB that occurs without upregulation of the corresponding gene and that may be caused by an increased CydAB activity in thylakoids, conceivably due to altered CydAB sorting between cytoplasmic and thylakoid membranes. Sll1717 appears to be unique to Synechocystis sp. strain PCC 6803 and has a close homologue encoded in the genome of this organism. The transcript level of sll1717 is low, which suggests that the corresponding protein is regulatory rather than structural.

scholarly journals Signal Transduction Protein PII Is Required for NtcA-Regulated Gene Expression during Nitrogen Deprivation in the Cyanobacterium Synechococcus elongatus Strain PCC 7942

2003 ◽  
Vol 185 (8) ◽  
pp. 2582-2591 ◽  
Author(s):  
M. Fadi Aldehni ◽  
Jörg Sauer ◽  
Christian Spielhaupter ◽  
Roland Schmid ◽  
Karl Forchhammer
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Synechococcus Elongatus ◽  
Dependent Manner ◽  
Nitrogen Deprivation ◽  
Wild Type ◽  
Combined Nitrogen ◽  
Signal Transduction Protein ◽  
Regulated Gene Expression ◽  
Pcc 7942

ABSTRACT The transcription factor of the cyclic AMP receptor protein/FNR family, NtcA, and the PII signaling protein play central roles in global nitrogen control in cyanobacteria. A dependence on PII for NtcA-regulated transcription, however, has not been observed. In the present investigation, we examined alterations in gene expression following nitrogen deprivation in Synechococcus elongatus strain PCC 7942 and specifically the roles of NtcA and PII. Global changes in de novo protein synthesis following combined-nitrogen deprivation were visualized by in vivo [35S]methionine labeling and two-dimensional polyacrylamide gel electrophoresis analysis. Nearly all proteins whose synthesis responded specifically to combined-nitrogen deprivation in wild-type cells of S. elongatus failed to respond in PII- and NtcA-deficient mutants. One of the proteins whose synthesis was down-regulated in a PII- and NtcA-dependent manner was RbcS, the small subunit of RubisCO. Quantification of its mRNA revealed that the abundance of the rbcLS transcript following combined-nitrogen deprivation rapidly declined in wild-type cells but not in PII and NtcA mutant cells. To investigate further the relationship between PII and NtcA, fusions of the promotorless luxAB reporter genes to the NtcA-regulated glnB gene were constructed and these constructs were used to transform wild-type cells and PII − and NtcA− mutants. Determination of bioluminescence under different growth conditions showed that NtcA represses gene expression in the presence of ammonium in a PII-independent manner. By contrast, NtcA-dependent activation of glnB expression following combined-nitrogen deprivation was impaired in the absence of PII. Together, these results suggest that under conditions of combined-nitrogen deprivation, the regulation of NtcA-dependent gene expression requires the PII signal transduction protein.

Subtle Impact of Akt1 and Akt3 on Exploratory Behavior in Gene Targeted Mice

2015 ◽  
Vol 223 (3) ◽  
pp. 173-180 ◽  
Author(s):  
Christina Leibrock ◽  
Michael Hierlmeier ◽  
Undine E. Lang ◽  
Florian Lang
Keyword(s):  
Forced Swimming Test ◽  
Open Field Test ◽  
Wild Type ◽  
Average Speed ◽  
Closed Area ◽  
Light Area ◽  
Swimming Test ◽  
The Impact ◽  
Center Area ◽  
Dark Transition

Abstract. The present study explored the impact of Akt1 and Akt3 on behavior. Akt1 (akt1-/-) and Akt3 (akt3-/-) knockout mice were compared to wild type (wt) mice. The akt1-/- mice, akt3-/- mice, and wt mice were similar in most parameters of the open-field test. However, the distance traveled in the center area was slightly but significantly less in akt3-/- mice than in wt mice. In the light/dark transition test akt1-/- mice had significantly lower values than wt mice and akt3-/- mice for distance traveled, number of rearings, rearing time in the light area, as well as time spent and distance traveled in the entrance area. They were significantly different from akt3-/- mice in the distance traveled, visits, number of rearings, rearing time in the light area, as well as time spent, distance traveled, number of rearings, and rearing time in the entrance area. In the O-maze the time spent, and the visits to open arms, as well as the number of protected and unprotected headdips were significantly less in akt1-/- mice than in wt mice, whereas the time spent in closed arms was significantly more in akt1-/- mice than in wt mice. Protected and unprotected headdips were significantly less in akt3-/- mice than in wt mice. In closed area, akt3-/- mice traveled a significantly larger distance at larger average speed than akt1-/- mice. No differences were observed between akt1-/- mice, akt3-/- mice and wt-type mice in the time of floating during the forced swimming test. In conclusion, akt1-/- mice and less so akt3-/ mice display subtle changes in behavior.

scholarly journals Structure of the Signal Transduction Domain in Second-Generation CAR Regulates the Input Efficiency of CAR Signals

2021 ◽  
Vol 22 (5) ◽  
pp. 2476
Author(s):  
Kento Fujiwara ◽  
Masaki Kitaura ◽  
Ayaka Tsunei ◽  
Hotaka Kusabuka ◽  
Erika Ogaki ◽  
...  
Keyword(s):  
Signal Transduction ◽  
T Cells ◽  
T Cell ◽  
Second Generation ◽  
Independent Manner ◽  
Cell Functions ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
The Impact

T cells that are genetically engineered to express chimeric antigen receptor (CAR) have a strong potential to eliminate tumor cells, yet the CAR-T cells may also induce severe side effects due to an excessive immune response. Although optimization of the CAR structure is expected to improve the efficacy and toxicity of CAR-T cells, the relationship between CAR structure and CAR-T cell functions remains unclear. Here, we constructed second-generation CARs incorporating a signal transduction domain (STD) derived from CD3ζ and a 2nd STD derived from CD28, CD278, CD27, CD134, or CD137, and investigated the impact of the STD structure and signaling on CAR-T cell functions. Cytokine secretion of CAR-T cells was enhanced by 2nd STD signaling. T cells expressing CAR with CD278-STD or CD137-STD proliferated in an antigen-independent manner by their STD tonic signaling. CAR-T cells incorporating CD28-STD or CD278-STD between TMD and CD3ζ-STD showed higher cytotoxicity than first-generation CAR or second-generation CARs with other 2nd STDs. The potent cytotoxicity of these CAR-T cells was not affected by inhibiting the 2nd STD signals, but was eliminated by placing the STDs after the CD3ζ-STD. Our data highlighted that CAR activity was affected by STD structure as well as by 2nd STD signaling.

scholarly journals Titanium Dioxide Presents a Different Profile in Dextran Sodium Sulphate-Induced Experimental Colitis in Mice Lacking the IBD Risk Gene Ptpn2 in Myeloid Cells

2021 ◽  
Vol 22 (2) ◽  
pp. 772
Author(s):  
Javier Conde ◽  
Marlene Schwarzfischer ◽  
Egle Katkeviciute ◽  
Janine Häfliger ◽  
Anna Niechcial ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Titanium Dioxide ◽  
Genetic Risk ◽  
Intestinal Inflammation ◽  
Sodium Sulphate ◽  
Food Additive ◽  
Wild Type ◽  
Dextran Sodium Sulphate ◽  
Risk Gene ◽  
The Impact

Environmental and genetic factors have been demonstrated to contribute to the development of inflammatory bowel disease (IBD). Recent studies suggested that the food additive; titanium dioxide (TiO2) might play a causative role in the disease. Therefore, in the present study we aimed to explore the interaction between the food additive TiO2 and the well-characterized IBD risk gene protein tyrosine phosphatase non-receptor type 2 (Ptpn2) and their role in the development of intestinal inflammation. Dextran sodium sulphate (DSS)-induced acute colitis was performed in mice lacking the expression of Ptpn2 in myeloid cells (Ptpn2LysMCre) or their wild type littermates (Ptpn2fl/fl) and exposed to the microparticle TiO2. The impact of Ptpn2 on TiO2 signalling pathways and TiO2-induced IL-1β and IL-10 levels were studied using bone marrow-derived macrophages (BMDMs). Ptpn2LysMCre exposed to TiO2 exhibited more severe intestinal inflammation than their wild type counterparts. This effect was likely due to the impact of TiO2 on the differentiation of intestinal macrophages, suppressing the number of anti-inflammatory macrophages in Ptpn2 deficient mice. Moreover, we also found that TiO2 was able to induce the secretion of IL-1β via mitogen-activated proteins kinases (MAPKs) and to repress the expression of IL-10 in bone marrow-derived macrophages via MAPK-independent pathways. This is the first evidence of the cooperation between the genetic risk factor Ptpn2 and the environmental factor TiO2 in the regulation of intestinal inflammation. The results presented here suggest that the ingestion of certain industrial compounds should be taken into account, especially in individuals with increased genetic risk

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