The Importance Of Overexpression

Submitted By mnbnm
Words: 7241
Pages: 29
Open Document
The regulation of intracellular ion concentrations is a fundamental property of living cells. Although many ion transporters have been identified, the systems that modulate their activity remain largely unknown. We have characterized two partially redundant genes from Saccharomyces cerevisiae, HAL4/SAT4 and HAL5, that encode homologous protein kinases implicated in the regulation of cation uptake. Overexpression of these genes increases the tolerance of yeast cells to sodium and lithium, whereas gene disruptions result in greater cation sensitivity. These phenotypic effects of the mutations correlate with changes in cation uptake and are dependent on a functional Trk1-Trk2 potassium transport system. In addition, hal4 hal5 and trk1 trk2 mutants exhibit similar phenotypes: (i) they are deficient in potassium uptake; (ii) their growth is sensitive to a variety of toxic cations, including lithium, sodium, calcium, tetramethylammonium, hygromycin B, and low pH; and (iii) they exhibit increased uptake of methylammonium, an indicator of membrane potential. These results suggest that the Hal4 and Hal5 protein kinases activate the Trk1-Trk2 potassium transporter, increasing the influx of potassium and decreasing the membrane potential. The resulting loss in electrical driving force reduces the uptake of toxic cations and improves salt tolerance. Our data support a role for regulation of membrane potential in adaptation to salt stress that is mediated by the Hal4 and Hal5 kinases.
The regulation of intracellular ion concentrations is a fundamental property of living cells. Although many ion transporters have been identified, the systems that modulate their activity remain largely unknown. We have characterized two partially redundant genes from Saccharomyces cerevisiae, HAL4/SAT4 and HAL5, that encode homologous protein kinases implicated in the regulation of cation uptake. Overexpression of these genes increases the tolerance of yeast cells to sodium and lithium, whereas gene disruptions result in greater cation sensitivity. These phenotypic effects of the mutations correlate with changes in cation uptake and are dependent on a functional Trk1-Trk2 potassium transport system. In addition, hal4 hal5 and trk1 trk2 mutants exhibit similar phenotypes: (i) they are deficient in potassium uptake; (ii) their growth is sensitive to a variety of toxic cations, including lithium, sodium, calcium, tetramethylammonium, hygromycin B, and low pH; and (iii) they exhibit increased uptake of methylammonium, an indicator of membrane potential. These results suggest that the Hal4 and Hal5 protein kinases activate the Trk1-Trk2 potassium transporter, increasing the influx of potassium and decreasing the membrane potential. The resulting loss in electrical driving force reduces the uptake of toxic cations and improves salt tolerance. Our data support a role for regulation of membrane potential in adaptation to salt stress that is mediated by the Hal4 and Hal5 kinases.
The regulation of intracellular ion concentrations is a fundamental property of living cells. Although many ion transporters have been identified, the systems that modulate their activity remain largely unknown. We have characterized two partially redundant genes from Saccharomyces cerevisiae, HAL4/SAT4 and HAL5, that encode homologous protein kinases implicated in the regulation of cation uptake. Overexpression of these genes increases the tolerance of yeast cells to sodium and lithium, whereas gene disruptions result in greater cation sensitivity. These phenotypic effects of the mutations correlate with changes in cation uptake and are dependent on a functional Trk1-Trk2 potassium transport system. In addition, hal4 hal5 and trk1 trk2 mutants exhibit similar phenotypes: (i) they are deficient in potassium uptake; (ii) their growth is sensitive to a variety of toxic cations, including lithium, sodium, calcium, tetramethylammonium, hygromycin B, and low pH; and (iii) they exhibit
Show More

Related Documents: The Importance Of Overexpression

Financial Literacy Essay

Interphase In this stage, the cell is preparing for the M Phase (Mitosis). The cell is continuously making RNA, producing protein, and growing. Interphase is broken into 4 parts: G0, G1, S, and G2. In G0, the cell leaves the cycle to stop its division. This period may be permanent, temporary or never happen at all. In G1, the cells grow and make RNA and protein. This phase is the midway between mitosis and the beginning of DNA replication. During G1, certain intracellular parts are replicated…

Words 1078 - Pages 5

Biology: Signal Transduction and Protein Kinases Essay

Ligand- signaling molecule like calcium Receptor protein- molecule to which the receptor binds Signal transduction- the interaction of ligand and receptor proteins initiates this process, which converts the information in the signal into a cellular response. Events within the cell that occur in response to a signal, different cell types can respond differently to the same signal. An example is epinephrine. 4 mechanisms for cell communications are: 1. Direct contact- Molecules on the plasma membrane…

Words 1083 - Pages 5

Seminar Synopsis Essay

the presence of C1q for 4-5 hours. They observed that in the treatment, phagocytosis was a time dependent process, which indicated that the presence of C1q was relaying gene transcription to produce phagocytosis gene-products. To further support the hypothesis and the latter results, another experiment was performed in which protein production was blocked with the use of a chemical known as cyclohexamine. This second experiment consisted of a control set of macrophage cells in the presence of HSA,…

Words 1025 - Pages 5

Sca1 Disease Case Study

SCA1 is caused by expansion of unstable CAG repeat. The longer the CAG repeat the earlier the age of onset. CAG encodes for amino acid glutamine. A heterozygous abnormal (CAG)n trinucleotide in ATXN1 gene, on chromosome 6p22, containing an abnormally lengthened stretch of amino acid glutamine. 5] Which organ and cell type are primary affected by the mutation? Is this consistent with the symptoms observed in SCA1 patients? This neurodegenerative disease…

Words 831 - Pages 4

Podiatry: Signal Transduction and Receptor Essay examples

the progressive loss of memory. Provide a speculative series of events (use signaling pathways if applicable) that would lead to the progressive degeneration of memory function. Is there a way to measure the changes? Oct 15 AB amyloid signaling protein which induce toxicity AB dimer will lead to hyperphosphorylated Tau causing tangles, protesome, Ca dysfunction, and mitcohondria will create ROS. Tau stabilizes MT but overexpression of Tau has detrimental effect Since mGluR2 contribute to memory…

Words 3934 - Pages 16

Physics: Cancer and Genetics Home Reference Essay

(Pennery and others 2009) Genes associated with inherited breast cancer are the BRCA1 (Breast/Ovarian cancer risk 1) gene on the 17th chromosome and the BRCA2 (Breast/Ovarian cancer risk 2) on the 13th chromosome. A mutation on the BRCA1 gene confers a lifetime risk of breast cancer of around 75%, in addition to an increased risk of ovarian, prostate, and colon cancer. Disease onset with mutated BRCA1 is typically at a relatively early age. A mutation on the BRCA2 gene results in a lifetime risk…

Words 1956 - Pages 8

Exploring The Kinetics: Bilateral And Unilateral Retinoblastomas

K-Ras protein molecules. Out of the four Ras proteins (H-, N-, and two K-Ras proteins), H-Ras is the only protein that depends entirely on its farnesyl group for function. N-Ras and K-Ras have alternative lipid groups attached to their C-termini such as geranylgeranyl, which allow them to continue to function as normal. Also, H-Ras oncoprotein is activated in less than 5% of tumor containing Ras oncogenes. This limits the efficacy of any FTIs that might be successively developed. These protein links…

Words 1006 - Pages 5

Lung Cancer Essay

cancer histology and gene mapping. The identification of mutations in lung cancer has led to the development of molecularly targeted therapy to improve the survival of patients with metastatic disease (Pao, 2011). In particular, subgroups of adenocarcinoma (type of NSCLC) can be defined by specific mutations in gene encoding components of epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (MAPK) and phosphatidylinositol 3-kinases (PI3K). EGFR is a tyrosine kinase that participates…

Words 3602 - Pages 15

JC Virus Agnoprotein Research Proposal Essay

genome contains three functional regions: the early region, encoding the large and small T antigens; the late region, encoding the structural proteins VP1, VP2, and VP3 and the late auxiliary agnoprotein; and a noncoding regulatory region. Agnoprotein is a 71 amino acid protein of unknown function. In JCV infected and agnoprotein transfected cells, the 8kDa protein is found predominantly in the cytoplasm with strong perinuclear localization. However, some agnoprotein is apparent in the nucleus, and a…

Words 6368 - Pages 26

the bug Essay

ffffffffffffffffffffffffffffffffffffffffffffffffffffffff.The major gene associated with melanoma is CDKN2A/p16, cyclin-dependent kinase inhibitor 2A, which is located on chromosome 9p21. This gene has multiple names (MTS1, INK4, and MLM) and is commonly called by the name of its protein, p16. It is an upstream regulator of the retinoblastoma gene pathway, acting through the cyclin D1/cyclin-dependent kinase 4 complex. This tumor suppressor gene has been intensively studied in multiple-case families and in…

Words 667 - Pages 3