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1.  Genetic Variations in the KCNJ5 Gene in Primary Aldosteronism Patients from Xinjiang, China 
PLoS ONE  2013;8(1):e54051.
Background
Primary aldosteronism (PA) is the most common endocrine form of secondary hypertension, and one of the most common subtypes of sporadic PA is aldosterone-producing adenoma (APA). Recently, two somatic mutations of the KCNJ5 gene were implicated in APA, and two germline mutations were associated with familial hyperaldosteronism III.
Objectives
This case-control study was designed to investigate the relationship between genetic variations in the KCNJ5 gene and sporadic PA patients in Xinjiang, China.
Methods
Five common single nucleotide polymorphisms (SNPs) of the KCNJ5 gene (rs6590357, rs4937391, rs3740835, rs2604204, and rs11221497) were detected in patients with sporadic PA (n = 235) and essential hypertension (EH; n = 913) by the TaqMan polymerase chain reaction method.
Results
The EH group and the PA group showed significant differences in the distributions of genotypes and alleles of rs4937391 and rs2604204 in total and male subjects (P<0.05), as well as rs3740835 in male subjects (P<0.05). However, only the association between the rs2604204 genotype and male sporadic PA remained significant after Bonferroni’s correction (P<0.01). Furthermore, logistic regression analysis demonstrated that the CC genotype of rs2604204 was a risk factor for male patients with sporadic PA, after adjusting for age and body mass index (odds ratio = 2.228, 95% CI: 1.300–3.819, P = 0.004).
Conclusion
The genetic variant rs2604204 of KCNJ5 is associated with sporadic PA in Chinese males, suggesting that KCNJ5 may be involved in the pathogenesis of sporadic PA in these particular patients.
doi:10.1371/journal.pone.0054051
PMCID: PMC3561325  PMID: 23382865
2.  Hepatitis B viral core protein disrupts human host gene expression by binding to promoter regions 
BMC Genomics  2012;13:563.
Background
The core protein (HBc) of hepatitis B virus (HBV) has been implicated in the malignant transformation of chronically-infected hepatocytes and displays pleiotropic functions, including RNA- and DNA-binding activities. However, the mechanism by which HBc interacts with the human genome to exert effects on hepatocyte function remains unknown. This study investigated the distribution of HBc binding to promoters in the human genome and evaluated its effects on the related genes’ expression.
Results
Whole-genome chromatin immunoprecipitation microarray (ChIP-on-chip) analysis was used to identify HBc-bound human gene promoters. Gene Ontology and pathway analyses were performed on related genes. The quantitative polymerase chain reaction assay was used to verify ChIP-on-chip results. Five novel genes were selected for luciferase reporter assay evaluation to assess the influence of HBc promoter binding. The HBc antibody immunoprecipitated approximately 3100 human gene promoters. Among these, 1993 are associated with known biological processes, and 2208 regulate genes with defined molecular functions. In total, 1286 of the related genes mediate primary metabolic processes, and 1398 encode proteins with binding activity. Sixty-four of the promoters regulate genes related to the mitogen-activated protein kinase (MAPK) pathways, and 41 regulate Wnt/beta-catenin pathway genes. The reporter gene assay indicated that HBc binding up-regulates proto-oncogene tyrosine-protein kinase (SRC), type 1 insulin-like growth factor receptor (IGF1R), and neurotrophic tyrosine kinase receptor 2 (NTRK2), and down-regulates v-Ha-ras Harvey rat sarcoma viral oncogene (HRAS).
Conclusion
HBc has the ability to bind a large number of human gene promoters, and can disrupt normal host gene expression. Manipulation of the transcriptional profile in HBV-infected hepatocytes may represent a key pathogenic mechanism of HBV infection.
doi:10.1186/1471-2164-13-563
PMCID: PMC3484065  PMID: 23088787
Hepatitis B virus; Hepatitis B core protein; Chromatin immunoprecipitation microarray; ChIP-on-chip; Gene expression; DNA-protein interaction
3.  Up-regulation of platelet-derived growth factor-A is responsible for the failure of re-initiated interferon alpha treatment in hepatocellular carcinoma 
BMC Cancer  2012;12:439.
Background
Postoperative interferon-α(IFN-α) treatment delays hepatocellular carcinoma(HCC) recurrence and prolongs patient survival, and may thus be an effective form of adjuvant therapy. However, clinical observations found that HCC recurs in some patients within 8 months of IFN-α treatment being discontinued. We investigated whether HCC regrowth appears after IFN-α is discontinued, whether re-initiated IFN-α is effective, and the underlying mechanisms of IFN-α treatment.
Methods
The human HCC nude mouse model LCI-D20 was used to study the effects of IFN-α treatment, discontinued IFN-α treatment, and re-initiated IFN-α treatment on tumor growth. Tumor weight, microvessel density(MVD), serum vascular endothelial growth factor (VEGF), and tumor cell apoptosis were analyzed. Angiogenesis-related factors were studied using cDNA microarray in different tumor samples and confirmed using reverse transcription–polymerase chain reaction(RT-PCR) and Western blotting assays. Finally, imatinib was added with re-initiated IFN-α treatment to improve efficacy.
Results
IFN-α (1.5×107 U/kg/day for 20 days) suppressed HCC growth by 60.3% and decreased MVD by 52.2% compared with the control. However, tumor regrowth occurred after IFN-α was discontinued, and re-initiated IFN-α treatment was not effective for inhibiting tumor growth or reducing MVD compared with a saline-treated group. cDNA microarray showed VEGF was down-regulated while platelet-derived growth factor-A (PDGF-A) was up-regulated when IFN-α treatment was re-initiated. These findings were further confirmed with RT-PCR and Western blotting assay. The combination of imatinib with re-initiated IFN-α reduced HCC weight by 30.7% and decreased MVD by 31.1% compared with IFN-α treatment only (P=0.003 and 0.015, respectively).
Conclusion
Tumor regrowth occurred after IFN-α treatment was discontinued. Re-initiated IFN-α treatment was not effective and was associated with up-regulation of PDGF-A, while the VEGF remained suppressed. The combination of a PDGF-receptor inhibitor with IFN-α improved the effect of the re-initiated treatment.
doi:10.1186/1471-2407-12-439
PMCID: PMC3517454  PMID: 23025904
Hepatocellular carcinoma; Interferon-α; Platelet-derived growth factor-A; Vascular endothelial growth factor; Microvessel density
4.  A transcriptional-switch model for Slr1738-controlled gene expression in the cyanobacterium Synechocystis 
Background
Protein-DNA interactions play a crucial role in the life of biological organisms in controlling transcription, regulation, as well as DNA recombination and repair. The deep understanding of these processes, which requires the atomic description of the interactions occurring between the proteins and their DNA partners is often limited by the absence of a 3D structure of such complexes.
Results
In this study, using a method combining sequence homology, structural analogy modeling and biochemical data, we first build the 3D structure of the complex between the poorly-characterized PerR-like regulator Slr1738 and its target DNA, which controls the defences against metal and oxidative stresses in Synechocystis. In a second step, we propose an expanded version of the Slr1738-DNA structure, which accommodates the DNA binding of Slr1738 multimers, a feature likely operating in the complex Slr1738-mediated regulation of stress responses. Finally, in agreement with experimental data we present a 3D-structure of the Slr1738-DNA complex resulting from the binding of multimers of the FUR-like regulator onto its target DNA that possesses internal repeats.
Conclusion
Using a combination of different types of data, we build and validate a relevant model of the tridimensional structure of a biologically important protein-DNA complex. Then, based on published observations, we propose more elaborated multimeric models that may be biologically important to understand molecular mechanisms.
doi:10.1186/1472-6807-12-1
PMCID: PMC3293774  PMID: 22289274
5.  catena-Poly[copper(II)-bis­(μ-2-formyl-6-meth­oxy­phenolato-κ4 O 2,O 1:O 1,O 6)-[(methanol-κO)sodium]-μ-perchlorato-κ2 O:O′] 
In the title heterodinuclear complex, [CuNa(C8H7O3)2(ClO4)(CH3OH)]n, the CuII ion is five-coordinated by four O atoms from two 2-formyl-6-meth­oxy­phenolate anions and one O atom from a perchlorate anion in a distorted square-pyramidal geometry. The Na+ ion is six-coordinated by four O atoms from two 2-formyl-6-meth­oxy­phenolate ligands, one O atom of a methanol mol­ecule and one O atom of a perchlorate anion. The perchlorate anions link the Na+ and CuII ions, forming a chain along [010]. O—H⋯O hydrogen bonds connect the chains. π–π inter­actions are present between the benzene rings [centroid–centroid distances = 3.566 (2) and 3.702 (2) Å]. The O atoms of the perchlorate anion are disordered over two sets of sites, with an occupancy ratio of 0.481 (8):0.519 (8).
doi:10.1107/S1600536812000876
PMCID: PMC3274885  PMID: 22346832
6.  {μ-6,6′-Dimeth­oxy-2,2′-[ethane-1,2-diyl­bis(nitrilo­methanylyl­idene)]diphenolato-1κ4 O 6,O 1,O 1′,O 6′;2κ4 O 1,N,N′,O 1′}(methanol-1κO)(tetra­fluoridoborato-1κ2 F,F′)-2-copper(II)-1-sodium 
In the dinuclear salen-type title complex, [CuNa(BF4)(C18H18N2O4)(CH3OH)], the CuII atom is chelated by two O atoms and two N atoms of the deprotonated Schiff base in a square-planar geometry. The Na atom is seven-coordinate as it is linked to four O atoms of the same Schiff base ligand, one O atom of the methanol and two tetra­fluorido­borate F atoms. The remaining two F atoms of the anion are disordered over two sites in a 0.598 (18):0.402 (18) ratio.
doi:10.1107/S160053681102842X
PMCID: PMC3212189  PMID: 22090891
7.  Detection of HBV Genotypes of Tumor Tissues and Serum by A Fluorescence Polarization Assay in North-Western China's Hepatocellular Carcinoma Patients 
Virology Journal  2011;8:362.
Background
The understanding of the distribution of hepatitis B virus genotypes and the occult hepatitis B virus infection in hepatocellular carcinoma may shed light into the prevention and treatment of hepatocellular carcinoma. The purpose of the study is to investigate hepatitis B virus genotypes distribution, the high-risk genotypes and the occult infection in north-western China's hepatocellular carcinoma patients.
Methods
Hepatitis B virus genotypes A-D of hepatocellular carcinoma tumor tissues and serum samples in 268 north-western China hepatocellular carcinoma patients were detected by fluorescence polarization assay. The hepatitis B virus genotypes in serum and matched primary tumor tissue samples were compared. Hepatitis B surface antigen and α-fetoprotein in serum were detected. Occult hepatitis B virus infections were analyzed. The relationship between hepatitis B virus genotypes and clinicopathologic characteristics were analyzed statistically using SPSS v.10.0.
Results
Intrahepatic hepatitis B virus DNA was detected in 83.6% of 268 patients, whereas serum hepatitis B virus DNA was detected in 78.7%. The hepatitis B virus genotypes in serum were consistent with the results in matched tumor tissue. Intrahepatic hepatitis B virus genotype B and C were detected respectively in 11.6% and 54.5% of the patients. Mixed intrahepatic hepatitis B virus genotypes were detected in 13.4% of 268 patients. There was not mixed hepatitis B virus infection in Edmondonson grade I. The patients with mixed HBV genotypes exhibited statistically significant different Edmondson grade than the patients with single type HBV infection (p < 0.05). Hepatitis B surface antigens were positive in 77.2% of 268 patients. Hepatitis B virus genotype C was detected in 64.7% of occult infected patients. There was no significant differences of patients' ages and α-fetoprotein level in different groups of intrahepatic hepatitis B virus genotypes (p > 0.05).
Conclusions
Hepatitis B virus genotype C was associated closely with the development of hepatocellular carcinoma and the occult hepatitis B virus infection in patients in north-western China. There was a relatively high prevalence of mixed hepatitis B virus infection in Edmondonson grade III-IV.
doi:10.1186/1743-422X-8-362
PMCID: PMC3152914  PMID: 21781311
hepatitis B virus genotype; hepatocellular carcinoma; fluorescence polarization; north-western China
8.  High Expression of Macrophage Colony-Stimulating Factor-1 Receptor in Peritumoral Liver Tissue Is Associated with Poor Outcome in Hepatocellular Carcinoma After Curative Resection 
The Oncologist  2010;15(7):732-743.
Peritumoral colony-stimulating factor 1 receptor (CSF-1R) is associated with intrahepatic metastasis, tumor recurrence, and patient survival after hepatectomy, highlighting the critical role of the peritumoral liver milieu in hepatocellular carcinoma progression. CSF-1R may become a potential therapeutic target for postoperative adjuvant treatment.
Background.
Macrophage colony-stimulating factor 1 receptor (CSF-1R) expression in hepatocellular carcinoma (HCC) and its prognostic values are unclear. This study evaluated the prognostic values of the intratumoral and peritumoral expression of CSF-1R in HCC patients after curative resection.
Methods.
Tissue microarrays containing material from cohort 1 (105 patients) and cohort 2 (32 patients) were constructed. Immunohistochemistry was performed and prognostic values of these and other clinicopathological data were evaluated. The CSF-1R mRNA level was assessed by quantitative real-time polymerase chain reaction in cohort 3 (52 patients).
Results.
Both the CSF-1R density and its mRNA level were significantly higher in peritumoral liver tissue than in the corresponding tumor tissue. CSF-1R was distributed in a gradient in the long-distance peritumoral tissue microarray, with its density decreasing as the distance from the tumor margin increased. High peritumoral CSF-1R was significantly associated with more intrahepatic metastases and poorer survival. Peritumoral CSF-1R was an independent prognostic factor for both overall survival and time to recurrence and affected the incidence of early recurrence. However, intratumoral CSF-1R did not correlate with any clinicopathological feature. Peritumoral CSF-1R was also associated with both overall survival and time to recurrence in a subgroup with small HCCs (≤5 cm).
Conclusions.
Peritumoral CSF-1R is associated with intrahepatic metastasis, tumor recurrence, and patient survival after hepatectomy, highlighting the critical role of the peritumoral liver milieu in HCC progression. CSF-1R may become a potential therapeutic target for postoperative adjuvant treatment.
doi:10.1634/theoncologist.2009-0170
PMCID: PMC3228006  PMID: 20551429
Macrophage colony-stimulating factor-1 receptor; Hepatocellular carcinoma; Microenvironment; Peritumoral liver tissue; Prognosis
9.  Overexpression of Sterol Carrier Protein 2 in Patients with Hereditary Cholesterol Gallstones 
BMC Gastroenterology  2011;11:10.
Background
Lithogenic bile is the major cause of cholesterol gallstone, but its pathogenesis is not well understood. The hypersecretion of biliary cholesterol is believed to be an important cause of lithogenic bile. Sterol Carrier Protein 2 (SCP2) participates in cholesterol trafficking and lipid metabolism in hepatocytes and may play a key role in cholesterol gallstone formation.
Methods
21 cholesterol gallstone genealogies were studied to investigate the expression of SCP2 gene in liver tissue of hereditary and non-hereditary cholesterol gallstone patients as well as non-gallstone patients. The mRNA expression of liver SCP2 in 28 hereditary patients, 30 non-hereditary cholesterol gallstone patients and 32 non-gallstone patients was measured by Reverse Transcription Polymerase Chain Reaction (RT-PCR). The protein expression of liver SCP2 was also detected in all the patients by Western blotting. At the same time, the bile was also analyzed with biochemical techniques and the Cholesterol Saturation Index (CSI) was calculated.
Results
The mRNA and protein expression of SCP2 was significantly increased in cholesterol gallstone patients compared to those of non-gallstone patients. Moreover, SCP2 was expressed at higher levels in hereditary cholesterol gallstone patients than that of non-hereditary cholesterol gallstone patients. There was significant difference observed in CSI between cholesterol gallstone patients and non-gallstone patients, but not in CSI between hereditary and non-hereditary cholesterol gallstone patients.
Conclusions
SCP2 was overexpressed in hereditary cholesterol gallstone patients compared to non-hereditary cholesterol gallstone patients. This finding indicated that SCP2 might be one of the genetic factors contributing to cholesterol gallstone formation, which was always accompanied by the increase of bile lithogenicity.
doi:10.1186/1471-230X-11-10
PMCID: PMC3042972  PMID: 21310066
10.  Antiangiogenic effects of pazopanib in xenograft hepatocellular carcinoma models: evaluation by quantitative contrast-enhanced ultrasonography 
BMC Cancer  2011;11:28.
Background
Antiangiogenesis is a promising therapy for advanced hepatocellular carcinoma (HCC), but the effects are difficult to be evaluated. Pazopanib (GW786034B) is a pan-vascular endothelial growth factor receptor inhibitor, the antitumor effects or antiangiogenic effects haven't been investigated in HCC.
Methods
In vitro direct effects of pazopanib on human HCC cell lines and endothelial cells were evaluated. In vivo antitumor effects were evaluated in three xenograft nude mice models. In the subcutaneous HCCLM3 model, intratumoral blood perfusion was detected by contrast-enhanced ultrasonography (CEUS), and serial quantitative parameters were profiled from the time-intensity curves of ultrasonograms.
Results
In vitro proliferation of various HCC cell lines were not inhibited by pazopanib. Pazopanib inhibited migration and invasion and induced apoptosis significantly in two HCC cell lines, HCCLM3 and PLC/PRF/5. Proliferation, migration, and tubule formation of human umbilical vein endothelial cells were inhibited by pazopanib in a dose-dependent manner. In vivo tumor growth was significantly inhibited by pazopanib in HCCLM3, HepG2, and PLC/PRF/5 xenograft models. Various intratumoral perfusion parameters changed over time, and the signal intensity was significantly impaired in the treated tumors before the treatment efficacy on tumor size could be observed. Mean transit time of the contrast media in hotspot areas of the tumors was reversely correlated with intratumoral microvessel density.
Conclusions
Antitumor effects of pazopanib in HCC xenografts may owe to its antiangiogenic effects, and the in vivo antiangiogenic effects could be evaluated by quantitative CEUS.
doi:10.1186/1471-2407-11-28
PMCID: PMC3033852  PMID: 21251271
11.  Potent anti-tumor activity of telomerase-dependent and HSV-TK armed oncolytic adenovirus for non-small cell lung cancer in vitro and in vivo 
Background
Non-small cell lung cancer (NSCLC) is the leading cause of cancer related mortality, any improvements in therapeutic strategies are urgently required. In this study we generated a novel 'suicide gene' armed oncolytic adenoviral vector and investigated its antitumor effect both in vitro and in vivo.
Methods
Since the up-regulated expression of human telomerase reverse transcriptase (hTERT) is a hallmark of alltypes of NSCLC, we chose hTERT promoter to transcriptionally control E1A gene expression to obtain adenoviral replication in NSCLC. In order to further enhance anti-tumor effect of this oncolytic adenoviral vector, we inserted a 'suicide gene' i.e. Herpes Simplex Virus Thymidine Kinase (HSV-TK) into oncolytic adenoviral vector to engineer a novel armed oncolytic adenoviral vector 'Ad.hTERT-E1A-TK'.
Results
Ad.hTERT-E1A-TK efficiently killed different types of tumor cells including two types of NSCLC cells in vitro, causing no damage to normal primary fibroblasts. Furthermore, Ad.hTERT-E1A-TK infection combined with administration of prodrug gancyclovir (GCV) resulted in more potent cytotoxicity on NSCLC cells, and synergistically suppressed human NSCLC tumor growth in nude mice.
Conclusion
The results from this study showed that Ad.hTERT-E1A-TK/GCV could be a potent but safe anti-tumor strategy for NSCLC biotherapy.
doi:10.1186/1756-9966-29-52
PMCID: PMC2890545  PMID: 20487549
12.  Helicobacter pylori infection in the pharynx of patients with chronic pharyngitis detected with TDI-FP and modified Giemsa stain 
AIM
To detect whether there is Helicobacter pylori (H pylori) colonization in the pharynx mucous membrane of healthy people and whether chronic pharyngitis is related to H pylori infection.
METHODS
Fifty cases of chronic pharyngitis refractory over three months were prospectively studied from March 2004 to August 2004 in the otolaryngology outpatient department of the Second Hospital of Xi’an Jiaotong University. Template-directed dye-terminator incorporated with fluorescence polarization detection (TDI-FP) and modified Giemsa stain were used to examine pharynx mucous membrane tissue for H pylori colonization in the patients with chronic pharyngitis and the healthy people as a control group.
RESULTS
In the control group, no people were detected to have H pylori in the pharynx. In contrast, in 50 cases with chronic pharyngitis, 19 (38.0%) cases were H pylori positive with a TDI-FP assay and 4 (8%) cases were TDI-FP positive with Giemsa staining in the pharynx. Sixteen of the 50 pharyngitis cases had stomach ailment history, 11 cases (68.8%) of these 16 patients were determined to be H pylori positive in the pharynx with the TDI-FP assay. χ2 test showed that this infection rate was remarkably higher (P = 0.0007) than that in the cases without stomach ailment history. Giemsa staining showed that 3 cases (18.8%) of the patients with stomach ailment history were infected with H pylori in the pharynx, which was remarkably higher (P = 0.042) than that in the patients without stomach ailment history (1 case, which was 2.9%).
CONCLUSION
H pylori may not be detected in the pharynx of healthy people. Chronic pharyngitis may be related to H pylori infection. The infection rate with H pylori in the pharynx is higher in patients with stomach ailment histories than in patients without stomach ailment histories, suggesting that chronic pharyngitis may be related to stomach ailment history.
PMCID: PMC2855301  PMID: 16489652
Chronic pharyngitis; H pylori; Modified Giemsa stain
13.  4-[4-(Diethyl­amino)benzyl­ideneamino]-4H-1,2,4-triazole 
The title compound, C13H17N5, is a Schiff base synthesized by the reaction of 4-amino-4H-1,2,4-triazole and 4-(diethyl­amino)benzaldehyde. The triazole ring forms a dihedral angle of 5.77 (16)° with the benzene ring. The crystal structure is stabilized by an inter­molecular C—H⋯N hydrogen bond.
doi:10.1107/S1600536808009100
PMCID: PMC2961419  PMID: 21202708
14.  Dual Regulation of Proliferation and Growth Arrest in Prostatic Stromal Cells by Transforming Growth Factor-β1 
Endocrinology  2003;144(10):4280-4284.
In a preliminary study, we observed that TGF-β1 induced both proliferation and growth arrest in prostatic stromal cells, depending on the concentration of TGF-β1 used in the culture medium. In this study, we explored possible mechanisms of this dual effect of TGF-β. Primary cultures of prostatic stromal cells, established from clinical surgical specimens and treated with low doses of TGF-β1 (0.001–0.01 ng/ml), resulted in an increase in cell proliferation. The addition of neutralizing antibody against platelet-derived growth factor (PDGF)-BB, but not anti-PDGF-AA, abrogated this stimulatory effect of TGF-β1. TGF-β1 treatment resulted in a dose-related increase in PDGF-BB production as measured by ELISA. Cells underwent growth arrest at high concentrations of TGF-β1 (1.0 and 10 ng/ml). An inhibitor of cyclin-dependent kinase (cdk), p15INK4b, was up-regulated at both transcript and protein levels in these cultures by TGF-β1 in a dose-related manner as determined by RT-PCR and Western blot analysis. The transcript, but not the protein, for another cdk inhibitor, p21Cip1, was up-regulated with treatment of TGF-β1 to these cells. Levels of other cdk inhibitors, such as p16INK4a and p27Kip1, were constitutively expressed in prostatic stromal cells and were not significantly affected by TGF-β1 treatment. Finally, the growth arrest effect of TGF-β1 was abrogated when antisense oligonucleotides to p15INH4b, but not p21Cip1, were added to the culture medium. These data indicate that the dual effect of TGF-β1 is mediated, at least, by up-regulation of PDGF-BB and p15INK4b, respectively.
doi:10.1210/en.2003-0554
PMCID: PMC1364460  PMID: 12959966
BPH, Benign prostatic hyperplasia; cdk, cyclin-dependent kinase; FBS, fetal bovine serum; PDGF, platelet-derived growth factor; Smad, signaling molecules identified downstream of TGFβ superfamily ligands
15.  A Lithium-Sensitive and Sodium-Tolerant 3′-Phosphoadenosine-5′-Phosphatase Encoded by halA from the Cyanobacterium Arthrospira platensis Is Closely Related to Its Counterparts from Yeasts and Plants 
3′-Phosphoadenosine-5′-phosphatase (PAPase) is required for the removal of toxic 3′-phosphoadenosine-5′-phosphate (PAP) produced during sulfur assimilation in various eukaryotic organisms. This enzyme is a well-known target of lithium and sodium toxicity and has been used for the production of salt-resistant transgenic plants. In addition, PAPase has also been proposed as a target in the treatment of manic-depressive patients. One gene, halA, which could encode a protein closely related to the PAPases of yeasts and plants, was identified from the cyanobacterium Arthrospira (Spirulina) platensis. Phylogenic analysis indicated that proteins related to PAPases from several cyanobacteria were found in different clades, suggesting multiple origins of PAPases in cyanobacteria. The HalA polypeptide from A. platensis was overproduced in Escherichia coli and used for the characterization of its biochemical properties. HalA was dependent on Mg2+ for its activity and could use PAP or 3′-phosphoadenosine-5′-phosphosulfate as a substrate. HalA is sensitive to Li+ (50% inhibitory concentration [IC50] = 3.6 mM) but only slightly sensitive to Na+ (IC50 = 600 mM). The salt sensitivity of HalA was thus different from that of most of its eukaryotic counterparts, which are much more sensitive to both Li+ and Na+, but was comparable to the PAPase AtAHL (Hal2p-like protein) from Arabidopsis thaliana. The properties of HalA could help us to understand the structure-function relationship underlying the salt sensitivity of PAPases. The expression of halA improved the Li+ tolerance of E. coli, suggesting that the sulfur-assimilating pathway is a likely target of salt toxicity in bacteria as well.
doi:10.1128/AEM.72.1.245-251.2006
PMCID: PMC1352299  PMID: 16391050

Results 1-15 (15)