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Stefanowska K, Woźniak M, Sip A, Mrówczyńska L, Majka J, Kozak W, Dobrucka R, Ratajczak I. Characteristics of Chitosan Films with the Bioactive Substances-Caffeine and Propolis. J Funct Biomater 2023; 14:358. [PMID: 37504853 PMCID: PMC10381157 DOI: 10.3390/jfb14070358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/02/2023] [Accepted: 07/07/2023] [Indexed: 07/29/2023] Open
Abstract
Chitosan is a natural and biodegradable polymer with promising potential for biomedical applications. This study concerns the production of chitosan-based materials for future use in the medical industry. Bioactive substances-caffeine and ethanolic propolis extract (EEP)-were incorporated into a chitosan matrix to increase the bioactivity of the obtained films and improve their mechanical properties. Acetic and citric acids were used as solvents in the production of the chitosan-based films. The obtained materials were characterized in terms of their antibacterial and antifungal activities, as well as their mechanical properties, including tensile strength and elongation at break. Moreover, the chemical structures and surface morphologies of the films were assessed. The results showed that the solution consisting of chitosan, citric acid, caffeine, and EEP exhibited an excellent antiradical effect. The activity of this solution (99.13%) was comparable to that of the standard antioxidant Trolox (92.82%). In addition, the film obtained from this solution showed good antibacterial activity, mainly against Escherichia coli and Enterococcus faecalis. The results also revealed that the films produced with citric acid exhibited higher activity levels against pathogenic bacteria than the films obtained with acetic acid. The antimicrobial effect of the chitosan-based films could be further enhanced by adding bioactive additives such as caffeine and propolis extract. The mechanical tests showed that the solvents and additives used affected the mechanical properties of the films obtained. The film produced from chitosan and acetic acid was characterized by the highest tensile strength value (46.95 MPa) while the chitosan-based film with citric acid showed the lowest value (2.28 MPa). The addition of caffeine and propolis to the film based on chitosan with acetic acid decreased its tensile strength while in the case of the chitosan-based film with citric acid, an increase in strength was observed. The obtained results suggested that chitosan films with natural bioactive substances can be a promising alternative to the traditional materials used in the medical industry, for example, as including biodegradable wound dressings or probiotic encapsulation materials.
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Affiliation(s)
- Karolina Stefanowska
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland
| | - Magdalena Woźniak
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland
| | - Anna Sip
- Department of Biotechnology and Food Microbiology, Faculty of Food Science and Nutrition, Poznan University of Life Sciences, Wojska Polskiego 48, 60627 Poznań, Poland
| | - Lucyna Mrówczyńska
- Department of Cell Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61614 Poznań, Poland
| | - Jerzy Majka
- Department of Wood Science and Thermal Techniques, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 38/42, 60637 Poznań, Poland
| | - Wojciech Kozak
- Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznań University of Economics and Business, al. Niepodległości 10, 61875 Poznań, Poland
| | - Renata Dobrucka
- Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznań University of Economics and Business, al. Niepodległości 10, 61875 Poznań, Poland
| | - Izabela Ratajczak
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland
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Sydor M, Majka J, Rychlik M, Turbański W. Application of 3D Scanning Method to Assess Mounting Holes' Shape Instability of Pinewood. Materials (Basel) 2023; 16:2053. [PMID: 36903168 PMCID: PMC10004658 DOI: 10.3390/ma16052053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 02/23/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Swelling and shrinkage anisotropy affect the susceptibility to an assembly of wooden elements by changing designed clearances or interference fits. This work described the new method to measure mounting holes' moisture-induced shape instability and its verification using three sets of twin samples made of Scots pinewood. Each set of samples contained a pair with different grain patterns. All samples were conditioned under reference conditions (relative air humidity-RH = 60% and temperature 20 °C), and their moisture content (MC) reached equilibrium (10.7 ± 0.1%). On the side of each sample, the seven mounting holes of 12 mm in diameter were drilled. Immediately after drilling, Set 1 was used to measure the effective hole diameter with 15 cylindrical plug-gauges with diameters of 0.05 mm step, while Set 2 and Set 3 were separately re-seasoned by six months in two extreme conditions. Set 2 was conditioned with air at 85% RH (reached an equilibrium MC of 16.6 ± 0.5%), while Set 3 was exposed to air at 35% RH (reached an equilibrium MC of 7.6 ± 0.1%). Results of the plug gauge tests highlighted that holes in the samples subjected to swelling (Set 2) increased an effective diameter in the range of 12.2-12.3 mm (1.7-2.5%), while samples subjected to shrinking (Set 3) reduced the effective diameter to 11.9-11.95 mm (0.8-0.4%). To accurately reproduce the complex shape of the deformation, gypsum casts of holes were made. The 3D optical scanning method was used to read the gypsum casts' shape and dimensions. The 3D surface map of deviations analysis provided more detailed information than the plug-gauge test results. Both the shrinking and swelling of the samples changed the shapes and sizes of the holes, but shrinking reduced the effective diameter of the hole more than swelling increased it. The moisture-induced changes in the shape of holes are complex: the holes ovalized with a different range, depending on the wood grain pattern and hole depth, and were slightly extended in diameter at the bottom. Our study provides a new way to measure 3D hole initial shape changes in wooden elements during desorption and absorption.
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Affiliation(s)
- Maciej Sydor
- Department of Woodworking and Fundamentals of Machine Design, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, 60-637 Poznań, Poland
- Euroline sp. z o.o., 64-100 Leszno, Poland
| | - Jerzy Majka
- Department of Engineering Mechanics and Thermal Techniques, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - Michał Rychlik
- Institute of Applied Mechanics, Faculty of Mechanical Engineering, Poznan University of Technology, 60-965 Poznań, Poland
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Kusiak W, Majka J, Zborowska M, Ratajczak I. Chemical Composition and Related Properties of Lime (Tilia cordata Mill.) Bark and Wood as Affected by Tree Growth Conditions. Materials 2022; 15:ma15114033. [PMID: 35683335 PMCID: PMC9182011 DOI: 10.3390/ma15114033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/22/2022] [Accepted: 06/03/2022] [Indexed: 01/22/2023]
Abstract
Tilia cordata Mill. is a favourite tree used in urban spaces. For this reason, it is important to know its sensitivity to environmental stress, which is particularly burdensome for vegetation in urban spaces. The aim of the study was to investigate the properties necessary to control the growth of these trees and their subsequent use, i.e., chemical properties (percentage contents of cellulose, holocellulose, lignin, pentosans and substances soluble in NaOH and EtOH) as well as the chemical elements (K, Na, Mg, Ca and Fe, Zn, Cu, Pb, Cd, B, Ni, Cr, Al, As and Hg) and selected hygroscopic properties (hysteresis and sorption isotherms). Trees of Tilia cordata Mill. growing in environments exposed to environmental stress of varying severity were examined. Regardless of the growth conditions, in terms of its chemical composition, bark differs significantly from wood, showing twice the contents of soluble substances in NaOH and lignin and half the content of polysaccharides. Growth conditions clearly affect the range of selected chemical components in bark, e.g., substances soluble in ethanol, cellulose, or lignin. The main inorganic elements in bark and wood are Na, K, Ca, Mg and Zn. In bark, a relationship was found between the content of most chemical elements and differing environmental growth conditions. It was shown that environmental stress influenced the hygroscopic properties of wood and bark, which are a consequence of the percentage of chemical components.
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Affiliation(s)
- Władysław Kusiak
- Department of Forest Engineering, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland;
| | - Jerzy Majka
- Department of Wood Science and Thermal Techniques, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland;
| | - Magdalena Zborowska
- Department of Chemical Wood Technology, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznań, Poland;
| | - Izabela Ratajczak
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 75, 60-625 Poznań, Poland
- Correspondence:
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Zagajewski J, Wojcik-Grzybek D, Brzozowski B, Majka J, Magierowski M, Placha W, Lasota M, Laidler PM, Brzozowski T. Simultaneous detection of melatonin and six metabolites of L-tryptophan pathway in rat gastric mucosa. J Physiol Pharmacol 2021; 72. [PMID: 35485362 DOI: 10.26402/jpp.2021.6.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine synthesized in vertebrates mainly in the pineal gland, and is known to be involved mainly in thermoregulation and control of the circadian rhythm. That indoleamine can affect the auto-, para- and endocrine pathways, regulating body functions and affecting the metabolism of animals and humans. In addition to the pineal gland, melatonin can be synthesized in many extra-pineal tissues, mainly in the gastrointestinal tract. Previous studies have shown that melatonin plays an important role in the defense system of the gastrointestinal mucosa, demonstrating a protective effect on the gastrointestinal tract and the acceleration of healing of chronic ulcers through the scavenging of reactive oxygen metabolites (ROS) and the activation of protective nitric oxide (NO) and vasodilator neuropeptides released from the sensory afferent neurons. The process of converting the melatonin precursor L-tryptophan into melatonin is already known, but not all aspects of this process for the synthesis of other metabolites of this pathway have been fully elucidated and this issue remains poorly understood. In this study, the conversion of L-tryptophan to melatonin and other metabolites was determined in gastric mucosa collected from rats with or without intragastric (i.g.) melatonin or L-tryptophan administration, both administered at a single dose of 50 mg/kg. For the determination of five metabolites of L-tryptophan: kynurenine, 5-hydroxytryptamine, 5-hydroxytryptophan, anthranilic acid, indole-3-acetic acid together with melatonin, we have modified the previously developed high-performance liquid chromatography (HPLC) method using a native fluorescence detection system and UV-VIS. The obtained results show that: 1) L-tryptophan is converted into melatonin in the gastric mucosa during the day, e.g. after eating a meal containing L-tryptophan, as it was imitated and confirmed by our study, in which this amino acid was administered directly to the stomach, 2) the gastric mucosa is capable of producing melatonin in much greater amounts than those recorded in the blood serum of rats given a single dose of L-tryptophan, and 3) apart from melatonin, the only serum levels of these five metabolites of the L-tryptophan metabolic pathway are detectable, while their level in the gastric mucosa is low and barely detectable under physiological conditions. Our present observations support the notion that the gastric mucosa is one of the main sources of melatonin production from L-tryptophan outside the pineal gland.
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Affiliation(s)
- J Zagajewski
- Department of Biochemistry, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland.
| | - D Wojcik-Grzybek
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - B Brzozowski
- Department of Gastroenterology and Hepatology, the University Hospital, Jagiellonian University Medical College, Cracow, Poland
| | - J Majka
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - M Magierowski
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - W Placha
- Department of Biochemistry, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - M Lasota
- Department of Biochemistry, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - P M Laidler
- Department of Biochemistry, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
| | - T Brzozowski
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, Cracow, Poland
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Stanicka K, Dobrucka R, Woźniak M, Sip A, Majka J, Kozak W, Ratajczak I. The Effect of Chitosan Type on Biological and Physicochemical Properties of Films with Propolis Extract. Polymers (Basel) 2021; 13:polym13223888. [PMID: 34833186 PMCID: PMC8625764 DOI: 10.3390/polym13223888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/03/2021] [Accepted: 11/07/2021] [Indexed: 12/24/2022] Open
Abstract
The aim of the research was to determine the influence of chitosan type and propolis extract concentration on biological and physicochemical properties of chitosan-propolis films in terms of their applicability in food packaging. The films were prepared using three types of chitosan: from crab shells, medium and high molecular weight and propolis concentration in the range of 0.75-5.0%. The prepared polysaccharide films were tested for antimicrobial properties, oxygen transmission rate (OTR) and water vapor transmission rate (WVTR). Moreover, sorption tests and structural analysis were carried out. Microbiological tests indicated the best antimicrobial activity for the film consisting of high molecular weight chitosan and 5.0% propolis extract. Both the type of chitosan and propolis concentration affected transmission parameters-OTR and WVTR. The best barrier properties were recorded for the film composed of high molecular weight chitosan and 5.0% propolis extract. The results of sorption experiments showed a slight influence of chitosan type and a significant effect of propolis extract concentration on equilibrium moisture content of tested films. Moreover, propolis extract concentration affected monolayer water capacity (Mm) estimated using the Guggenheim, Anderson and de Boer (GAB) sorption model. The obtained results indicate that chitosan films with an addition of propolis extract are promising materials for food packaging applications, including food containing probiotic microorganisms.
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Affiliation(s)
- Karolina Stanicka
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland; (K.S.); (M.W.)
| | - Renata Dobrucka
- Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznań University of Economics and Business, al. Niepodległości 10, 61875 Poznań, Poland; (R.D.); (W.K.)
| | - Magdalena Woźniak
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland; (K.S.); (M.W.)
| | - Anna Sip
- Department of Biotechnology and Food Microbiology, Faculty of Food Science and Nutrition, Poznan University of Life Sciences, Wojska Polskiego 48, 60627 Poznań, Poland;
| | - Jerzy Majka
- Department of Wood Science and Thermal Technics, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 38/42, 60627 Poznań, Poland;
| | - Wojciech Kozak
- Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznań University of Economics and Business, al. Niepodległości 10, 61875 Poznań, Poland; (R.D.); (W.K.)
| | - Izabela Ratajczak
- Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 75, 60625 Poznań, Poland; (K.S.); (M.W.)
- Correspondence:
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Roszyk E, Stachowska E, Majka J, Mania P, Broda M. Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression. Materials (Basel) 2020; 13:ma13071647. [PMID: 32252320 PMCID: PMC7178349 DOI: 10.3390/ma13071647] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 03/28/2020] [Accepted: 03/30/2020] [Indexed: 11/29/2022]
Abstract
European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.
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Czekaj R, Majka J, Ptak-Belowska A, Szlachcic A, Targosz A, Magierowska K, Strzalka M, Magierowski M, Brzozowski T. Role of curcumin in protection of gastric mucosa against stress-induced gastric mucosal damage. Involvement of hypoacidity, vasoactive mediators and sensory neuropeptides. J Physiol Pharmacol 2016; 67:261-275. [PMID: 27226186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/04/2016] [Indexed: 06/05/2023]
Abstract
The antioxidizing properties of curcumin, a highly pleiotropic substance used for centuries in traditional medicine has been confirmed by numerous experimental and clinical studies. Curcumin exhibits anti-inflammatory, antiproliferative and anti-angiogenic actions inhibiting the development and progression of tumors but the efficacy of this compound to influence gastric acid secretion n in the stomach and to affect the gastric mucosal damage induced by non-topical ulcerogenes such as stress has been little studied. We determined the effect of curcumin on basal and pentagastrin- or histamine-stimulated gastric secretion, in rats with surgically implemented gastric fistulas and we assessed the contribution of gastric secretion, endogenous prostaglandin (PG), endogenous nitric oxide (NO), as well as sensory afferent nerves in the mechanisms underlying the potential gastroprotective effects of curcumin against stress-induced gastric mucosal lesions. Rats exposed to water immersion and restraint stress (WRS) for 3.5 h were pretreated either with: 1) vehicle (saline); 2) curcumin (2.5 - 100 mg/kg i.g.) or 3) curcumin (50 mg/kg i.g.) combined with or without indomethacin (5 mg/kg i.p.), SC-560 (5 mg/kg i.g.) or rofecoxib (10 mg/kg i.g.); 4) curcumin (50 mg/kg i.g.) co-administered with (L-NNA (20 mg/kg i.p.) with or without L-arginine (200 mg/kg i.g.), a substrate for NO-synthase; 5) curcumin (50 mg/kg i.g.) administered in rats with intact or capsaicin-induced functional ablation of sensory nerve fibers, and 6) curcumin (50 mg/kg i.g.) administered with capsazepine (5 mg/kg i.g.), the antagonist of vanilloid TRPV1 receptor. The number of gastric lesions was determined by planimetry, the gastric blood flow (GBF) was assessed by H2-gas clearance technique, the plasma gastrin concentrations were measured using the radioimmunoassay (RIA) and the expression of mRNA for tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in gastric mucosa was evaluated by reverse transcription polymerase chain reaction (RT-PCR). Curcumin dose-dependently reduced the WRS-induced gastric lesions, the dose inhibiting these lesions by 50% being about 50 mg/kg. These effects of curcumin were accompanied by an increase in GBF and the reduction in basal and histamine- or pentagastrin-stimulated gastric acid secretion. The protective and hyperemic activities of curcumin (50 mg/kg i.g.) against WRS lesions were significantly attenuated (P < 0.05) in rats pretreated with rofecoxib and SC-560 and completely reversed (P < 0.01) by indomethacin. L-NNA significantly reduced (P < 0.05) the decrease in WRS-induced lesions and the accompanying rise in GBF caused by curcumin and these effects were restored by concurrent treatment with L-arginine (200 mg/kg i.g.). The curcumin-induced decrease in the number of WRS-induced gastric lesions and accompanying increase in the GBF were significantly attenuated (P < 0.05) in capsaicin-denervated rats and in those pretreated with capsazepine. These effects of curcumin in rats with capsaicin denervation were restored by concomitant treatment with exogenous calcitonin gene related pepetide (CGRP) combined with curcumin and subsequently exposed to WRS. The expression of mRNA for TNF-α, COX-2 and iNOS was significantly increased (P < 0.05) in vehicle-pretreated control rats exposed to WRS and significantly attenuated (P < 0.05) by curcumin administered in graded dosages. We conclude that curcumin exerts gastroprotective and hyperemic activities against experimental stress-induced gastric lesions by mechanism involving endogenous prostaglandins, NO, the neuropeptides such as CGRP released from capsaicin-sensitive afferent nerves and the activation of vanilloid TRPV1 receptors located on these sensory nerve terminals.
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Affiliation(s)
- R Czekaj
- Zeromski Hospital Neurology Ward, Cracow, Poland
| | - J Majka
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - A Ptak-Belowska
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - A Szlachcic
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - A Targosz
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - K Magierowska
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - M Strzalka
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - M Magierowski
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
| | - T Brzozowski
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland.
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Szlachcic A, Majka J, Strzalka M, Szmyd J, Pajdo R, Ptak-Belowska A, Kwiecien S, Brzozowski T. Experimental healing of preexisting gastric ulcers induced by hormones controlling food intake ghrelin, orexin-A and nesfatin-1 is impaired under diabetic conditions. A key to understanding the diabetic gastropathy? J Physiol Pharmacol 2013; 64:625-637. [PMID: 24304576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
Hormonal peptides like ghrelin, orexin A (OXA) or nesfatin-1 not only regulate appetite, which is their basic biological function, but also contribute to mechanisms responsible for maintaining integrity of the gastric mucosa. Previous studies including those from our laboratory have revealed that their gastroprotective effect results from cooperation with other factors responsible for protection of the gastric mucosa, including prostaglandin (PG) synthesis pathway, nitric oxide (NO) and the sensory afferent fibres releasing the vasoactive neurotransmitters. The aim of the present study was to determine whether ghrelin, orexin-A (OX-A) or nesfatin-1 with their protective effect on the gastric mucosa, also can modify the healing of chronic gastric ulcers. Furthermore, an attempt was made to explain participation of these peptides in healing processes of chronic gastric ulcers with comorbid conditions for the human beings resulted from diabetes mellitus. In our study, a model of gastric ulcers caused by concentrated acetic acid to induce the chronic gastric ulcers was used, while the clinical condition corresponding to diabetes was induced by single injection of streptozotocin (STZ). We found that ghrelin, OX-A and nesfatin-1 accelerate dynamics of the acetic acid ulcers healing, confirmed by a reduction in the ulcer area and this effect was accompanied by an increase in gastric blood flow at the ulcer margin. Destruction of sensory afferent fibres with capsaicin or blocking of vanilloid receptors with capsazepine resulted in a significant reduction of ghrelin, OX-A and nesfatin-1-induced acceleration of ulcer healing. Similar results were obtained when an NO-synthase blocker, L-NNA was used in a combination with these peptides. Moreover, it was found that OX-A and nesfatin-1 failed to accelerate the healing process under diabetic condition because both these hormones induced reduction in the ulcer area and the increase in blood flow in normal, non-diabetic rats were completely lost in the group of animals with diabetes. Treatment with OX-A and nesfatin-1 increased superoxide dismutase (SOD) mRNA expression even in acetic acid ulcers concurrent with diabetes. However, the treatment with OX-A and nesfatin-1 failed to alter the increase in gastric mucosal mRNA expression for ghrelin and hypoxia-inducible factor 1-alpha (HIF-1α), this latter effect that had been strongly pronounced in diabetic animals. We conclude that the hormonal peptides involved in the regulation of satiety and hunger such as ghrelin, OX-A and nesfatin-1 contribute to the process of chronic gastric ulcers healing cooperating with NO and sensory afferent nerve endings releasing vasoactive neuropeptide CGRP. Furthermore, OX-A and nesfatin-1, the two relatively unrecognized peptides, play an essential role in healing process of chronic gastric ulcers activating the gastric blood flow at ulcer margin and the mucosal regeneration and both ulcer healing and accompanying hyperemia at ulcer margin are greatly impaired during diabetes. Possibly, loss of the healing effect of these peptides during diabetes results from an interaction with radical generation processes as reflected by an increase of mRNA expression for SOD as well as the failure of their attenuating activity on proinflammatory factors such as HIF-1α.
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Affiliation(s)
- A Szlachcic
- Department of Physiology Jagiellonian University Medical College, Cracow, Poland.
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Wallen JR, Majka J, Ellenberger T. Discrete interactions between bacteriophage T7 primase-helicase and DNA polymerase drive the formation of a priming complex containing two copies of DNA polymerase. Biochemistry 2013; 52:4026-36. [PMID: 23675753 DOI: 10.1021/bi400284j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Replisomes are multiprotein complexes that coordinate the synthesis of leading and lagging DNA strands to increase the replication efficiency and reduce DNA strand breaks caused by stalling of replication forks. The bacteriophage T7 replisome is an economical machine that requires only four proteins for processive, coupled synthesis of two DNA strands. Here we characterize a complex between T7 primase-helicase and DNA polymerase on DNA that was trapped during the initiation of Okazaki fragment synthesis from an RNA primer. This priming complex consists of two DNA polymerases and a primase-helicase hexamer that assemble on the DNA template in an RNA-dependent manner. The zinc binding domain of the primase-helicase is essential for trapping the RNA primer in complex with the polymerase, and a unique loop located on the thumb of the polymerase also stabilizes this primer extension complex. Whereas one of the polymerases engages the primase-helicase and RNA primer on the lagging strand of a model replication fork, the second polymerase in the complex is also functional and can bind a primed template DNA. These results indicate that the T7 primase-helicase specifically engages two copies of DNA polymerase, which would allow the coordination of leading and lagging strand synthesis at a replication fork. Assembly of the T7 replisome is driven by intimate interactions between the DNA polymerase and multiple subunits of the primase-helicase hexamer.
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Affiliation(s)
- Jamie R Wallen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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Majka J, Alford B, Ausio J, Finn RM, McMurray CT. ATP hydrolysis by RAD50 protein switches MRE11 enzyme from endonuclease to exonuclease. J Biol Chem 2011; 287:2328-41. [PMID: 22102415 DOI: 10.1074/jbc.m111.307041] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MRE11-RAD50 is a key early response protein for processing DNA ends of broken chromosomes for repair, yet how RAD50 nucleotide dynamics regulate MRE11 nuclease activity is poorly understood. We report here that ATP binding and ATP hydrolysis cause a striking butterfly-like opening and closing of the RAD50 subunits, and each structural state has a dramatic functional effect on MRE11. RAD50-MRE11 has an extended conformation in solution when MRE11 is an active nuclease. However, ATP binding to RAD50 induces a closed conformation, and in this state MRE11 is an endonuclease. ATP hydrolysis opens the RAD50-MRE11 complex, and MRE11 maintains exonuclease activity. Thus, ATP hydrolysis is a molecular switch that converts MRE11 from an endonuclease to an exonuclease. We propose a testable model in which the open-closed transitions are used by RAD50-MRE11 to discriminate among DNA ends and drive the choice of recombination pathways.
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Affiliation(s)
- Jerzy Majka
- Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, California 94720, USA
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12
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Lang WH, Coats JE, Majka J, Hura GL, Lin Y, Rasnik I, McMurray CT. Conformational trapping of mismatch recognition complex MSH2/MSH3 on repair-resistant DNA loops. Proc Natl Acad Sci U S A 2011; 108:E837-44. [PMID: 21960445 PMCID: PMC3198364 DOI: 10.1073/pnas.1105461108] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Insertion and deletion of small heteroduplex loops are common mutations in DNA, but why some loops are prone to mutation and others are efficiently repaired is unknown. Here we report that the mismatch recognition complex, MSH2/MSH3, discriminates between a repair-competent and a repair-resistant loop by sensing the conformational dynamics of their junctions. MSH2/MSH3 binds, bends, and dissociates from repair-competent loops to signal downstream repair. Repair-resistant Cytosine-Adenine-Guanine (CAG) loops adopt a unique DNA junction that traps nucleotide-bound MSH2/MSH3, and inhibits its dissociation from the DNA. We envision that junction dynamics is an active participant and a conformational regulator of repair signaling, and governs whether a loop is removed by MSH2/MSH3 or escapes to become a precursor for mutation.
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Affiliation(s)
- Walter H. Lang
- Lawrence Berkeley National Laboratory, Life Sciences Division, 1 Cyclotron Road, Berkeley, CA 94720
| | - Julie E. Coats
- Department of Physics, Emory University, 400 Dowman Drive, MSC N214, Atlanta, GA 30322
| | - Jerzy Majka
- Lawrence Berkeley National Laboratory, Life Sciences Division, 1 Cyclotron Road, Berkeley, CA 94720
| | - Greg L. Hura
- Lawrence Berkeley National Laboratory, Life Sciences Division, 1 Cyclotron Road, Berkeley, CA 94720
| | - Yuyen Lin
- Department of Physics, Emory University, 400 Dowman Drive, MSC N214, Atlanta, GA 30322
| | - Ivan Rasnik
- Department of Physics, Emory University, 400 Dowman Drive, MSC N214, Atlanta, GA 30322
| | - Cynthia T. McMurray
- Lawrence Berkeley National Laboratory, Life Sciences Division, 1 Cyclotron Road, Berkeley, CA 94720
- Department of Molecular Pharmacology and Experimental Therapeutics
- Department of Biochemistry and Molecular Biology, Mayo Foundation, 200 First Street, Rochester, MN 55905; and
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13
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Majka J, Rembiasz K, Migaczewski M, Budzynski A, Ptak-Belowska A, Pabianczyk R, Urbanczyk K, Zub-Pokrowiecka A, Matlok M, Brzozowski T. Cyclooxygenase-2 (COX-2) is the key event in pathophysiology of Barrett's esophagus. Lesson from experimental animal model and human subjects. J Physiol Pharmacol 2010; 61:409-418. [PMID: 20814068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 07/15/2010] [Indexed: 05/29/2023]
Abstract
Mixed reflux of the gastroduodenal contents induces the esophageal mucosal damage and inflammation progressing chronic esophagitis and premalignant Barrett's esophagus (BE). The role of cyclooxygenase-2 (COX-2) and chronic inflammation in the progression of BE toward adenocarcinoma of the esophagus has not been extensively studied in experimental models of BE in animals and in human subjects. We evaluated the expression of COX-2 in rat model of BE and examined the usefulness of COX-2 expression in determining the risk of malignant transformation in patients with BE treated with argon plasma coagulation (APC) that allows for effective ablation of metaplastic mucosa (group A) without or with proton pump inhibitors (PPI). In addition, the group B of patients was subjected to laparoscopic Nissen's fundoplication and group K that served as control, received PPI treatment only. Expression of COX-2 was evaluated in fresh-frozen biopsy specimens obtained from the distal esophagus in all 60 patients before and 12 months after treatment. In experimental studies, eighty rats were surgically prepared with esophagogastroduodenal anastomosis (EGDA) resulting in chronic esophagitis. At 4 months, the esophageal damage in EGDA rats was evaluated by macroscopic and histological index score, the plasma IL-1beta and TNF-alpha levels was determined by ELISA and the mucosal expression of COX-2 mRNA and COX-2 protein were assessed by RT-PCR and Western Blot, respectively. Chronic esophagitis was developed in all EGDA animals followed by the rise in the plasma TNF-alpha and IL-1beta levels. Histology revealed extensive esophageal ulcerations with development of columnar epithelium, formation of mucus glands in squamous epithelium, intestinal metaplasia distant to anastomosis consisting of goblet cells, infiltration of inflammatory cells including plasma cells and lymphocytes. COX-2 mRNA was absent in the esophageal mucosa of sham-control animals but strongly upregulated in metaplastic Barrett's epithelium. In BE patients, the overexpression of COX-2 was documented in patients with dysplasia. After APC (group A) or Nissen's fundoplication (group B), the expression of COX-2 mRNA was markedly reduced and these effects were positively correlated with histopathological findings. Controls failed to show significant alterations in COX-2 expression. We conclude that 1) EGDA rats serve as the suitable model of the chronic esophagitis by the gastrointestinal refluxate resembling many features of those observed in human Barrett's esophagus, as confirmed by severe morphology changes, excessive release of proinflammatory cytokines TNF-alpha and IL-1beta and overexpression of COX-2, and 2) the significant correlation of the degree of COX-2 overexpression with histopathological findings indicates the usefulness of this inducible biomarker as a valuable indicator of the risk of malignant transformation in patients with BE.
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Affiliation(s)
- J Majka
- Department of Physiology, Jagiellonian University Medical College, Cracow, Poland
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14
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Burnat G, Majka J, Konturek PC. Bile acids are multifunctional modulators of the Barrett's carcinogenesis. J Physiol Pharmacol 2010; 61:185-192. [PMID: 20436219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 03/19/2010] [Indexed: 05/29/2023]
Abstract
Bile salts play an important pathogenic role in the development of Barrett adenocarcinoma (BA). However, the precise role of different bile salts in this process is still unknown. The aim of the present study was to compare the effects of two different bile salts, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA) on the expression of COX-2, CDX-2 and DNA repair enzymes (MUTYH, OGG-1) in the Barrett epithelial cancer cells (OE-19). OE-19 cells were incubated with DCAor UDCA(100 microM or 300 microM at pH=7.0) over 24 h. To investigate the involvement of NF kappaB, in separate experiments the cells were incubated with DCA in the presence of proteosome inhibitor (MG-132). Cells cycle and apoptosis were analyzed by FACS analysis. After incubation of OE-19 cells with bile salts, the expression of mRNA of COX-2, DNA repair enzymes (MUTYH, OGG-1) and caudal-related homebox transcription factor CDX-2 were measured by quantitative RT-PCR. OE-19 cell were also transfected with siRNA-RelA (p65) to asses effect of NF kappaB inactivation on COX-2 and CDX2 expression. DCA caused a stronger reduction in cell survival of OE-19 cells than UDCA. In addition, DCA stimulated directly the translocation of NF kappaB p65 (active form) in the nuclei of OE-19 cells. DCA caused stronger than UDCA stimulation of the COX-2 mRNA expression in these cells and this effect was significantly attenuated by the addition of inhibitor of NF kappaB activity (proteosome inhibitor MG-132). siRNA-RelA reduced expression not only of NF kappaB but also expression of COX-2 as well as CDX-2 mRNA. DCA caused stronger downregulation of mRNA for DNA repair enzymes MUTYH and OGG-1 than UDCA. In contrast, UDCA induced stronger CDX-2 mRNA expression than DCA in OE-19 cells. We conclude that bile salts are involved in the carcinogenesis of Barrett adenocarcinoma via inhibition of DNA repair enzymes and induction of COX-2 and this last effect is, at least partly, mediated by NF kappaB. DCA shows carcinogenic potential due to high upregulation of COX-2, CDX-2 and downregulation of DNA repair enzymes.
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Affiliation(s)
- G Burnat
- Department of Medicine, Thuringia-Clinic Saalfeld, Teaching Hospital of the University of Jena, Germany
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15
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Lang W, Majka J, Owen B, Klugland A, Bjoras M, McMurray CT. Cause and consequences of genome instability in Huntington's Disease. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.411.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Walter Lang
- Life Sciences DivisionLawrence Berkeley LaboratoriesBerkeleyCA
| | - Jerzy Majka
- Life Sciences DivisionLawrence Berkeley LaboratoriesBerkeleyCA
| | - Barbara Owen
- Life Sciences DivisionLawrence Berkeley LaboratoriesBerkeleyCA
| | - Arne Klugland
- Department of Molecular BiologyInstitute of Medical MicrobiologyUniversity of OsloThe National HospitalOsloNorway
| | - Magnar Bjoras
- Department of Molecular BiologyInstitute of Medical MicrobiologyUniversity of OsloThe National HospitalOsloNorway
| | - Cynthia T. McMurray
- Life Sciences DivisionLawrence Berkeley LaboratoriesBerkeleyCA
- Department of Molecular Pharmacology and Experimental TherapeuticsMayo ClinicRochesterMN
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16
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Castagna M, Schertz J, O'Connor K, Majka J, Stern D. Identifying the role of cost in patients' decisions to continue infertility treatment. Fertil Steril 2008. [DOI: 10.1016/j.fertnstert.2008.07.803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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17
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Burgers PM, Navadgi VM, Majka J. The Ddc1 checkpoint clamp subunit activates Mec1 kinase during the DNA damage checkpoint. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.246.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Peter M Burgers
- Biochemistry and Molecular BiophysicsWashington University School of MedicineSt. LouisMO
| | - Vasundhara M Navadgi
- Biochemistry and Molecular BiophysicsWashington University School of MedicineSt. LouisMO
| | - Jerzy Majka
- Biochemistry and Molecular BiophysicsWashington University School of MedicineSt. LouisMO
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18
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Abstract
The yeast checkpoint protein kinase Mec1, the ortholog of human ATR, is the essential upstream regulator of the cell cycle checkpoint in response to DNA damage and to stalling of DNA replication forks. The activity of Mec1/ATR is not directly regulated by the DNA substrates that signal checkpoint activation. Rather the signal appears to be transduced to Mec1 by factors that interact with the signaling DNA substrates. One of these factors, the DNA damage checkpoint clamp Rad17-Mec3-Ddc1 (human 9-1-1) is loaded onto gapped DNA resulting from the partial repair of DNA damage, and the Ddc1 subunit of this complex activates Mec1. In vertebrate cells, the TopBP1 protein (Cut5 in S. pombe and Dpb11 in S. cervisiae) that is also required for establishment of the replication fork, functions during replication fork dysfunction to activate ATR. Both mechanisms of activation generally upregulate the kinase activity towards all downstream targets.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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19
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Majka J, Niedziela-Majka A, Burgers PMJ. The checkpoint clamp activates Mec1 kinase during initiation of the DNA damage checkpoint. Mol Cell 2007; 24:891-901. [PMID: 17189191 PMCID: PMC1850967 DOI: 10.1016/j.molcel.2006.11.027] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/17/2006] [Accepted: 11/30/2006] [Indexed: 11/22/2022]
Abstract
Yeast Mec1/Ddc2 protein kinase, the ortholog of human ATR/ATRIP, plays a central role in the DNA damage checkpoint. The PCNA-like clamp Rad17/Mec3/Ddc1 (the 9-1-1 complex in human) and its loader Rad24-RFC are also essential components of this signal transduction pathway. Here we have studied the role of the clamp in regulating Mec1, and we delineate how the signal generated by DNA lesions is transduced to the Rad53 effector kinase. The checkpoint clamp greatly activates the kinase activity of Mec1, but only if the clamp is appropriately loaded upon partial duplex DNA. Activated Mec1 phosphorylates the Ddc1 and Mec3 subunits of the clamp, the Rad24 subunit of the loader, and the Rpa1 and Rpa2 subunits of RPA. Phosphorylation of Rad53, and of human PHAS-1, a nonspecific target, also requires a properly loaded clamp. Phosphorylation and binding studies with individual clamp subunits indicate that the Ddc1 subunit mediates the functional interactions with Mec1.
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20
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Majka J, Speck C. Analysis of protein-DNA interactions using surface plasmon resonance. Adv Biochem Eng Biotechnol 2007; 104:13-36. [PMID: 17290817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Protein-DNA interactions are required for access and protection of the genetic information within the cell. Historically these interactions have been studied using genetic, biochemical, and structural methods resulting in qualitative or semiquantitative interaction data. In the future the focus will be on high quality quantitative data to model a huge number of interactions forming a specific network in system biology approaches. Toward this aim, BIAcore introduced in 1990 the first commercial machine that uses surface plasmon resonance (SPR) to study the real-time kinetics of biomolecular interactions. Since then systems have been developed to allow for robust analysis of a multitude of protein-DNA interactions. Here we provide a detailed guide for protein-DNA interaction analysis using the BIAcore, starting with a description of the SPR technology, giving recommendations on preliminary studies, and finishing with extensive information on quantitative and qualitative data analysis. One focus is on cooperative protein-DNA interactions, where proteins interact with each other to modulate their binding specificity or affinity. The BIAcore has been used for the last 14 years to study protein-DNA interactions; our literature review focuses on some high quality studies describing a wide range of experimental uses, covering simple 1 : 1 interactions, analysis of complicated multiprotein-DNA interaction systems, and analytical uses.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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21
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Smulczyk-Krawczyszyn A, Jakimowicz D, Ruban-Osmialowska B, Zawilak-Pawlik A, Majka J, Chater K, Zakrzewska-Czerwinska J. Cluster of DnaA boxes involved in regulation of Streptomyces chromosome replication: from in silico to in vivo studies. J Bacteriol 2006; 188:6184-94. [PMID: 16923885 PMCID: PMC1595370 DOI: 10.1128/jb.00528-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 06/12/2006] [Indexed: 11/20/2022] Open
Abstract
In Streptomyces coelicolor, replication is initiated by the DnaA protein in the centrally located oriC region and proceeds bidirectionally until the replication forks reach the ends of the linear chromosome. We identified three clusters of DnaA boxes (H69, H24, and D78) which are in a relatively short segment of the chromosome centered on the oriC region. Of the clusters analyzed, D78 exhibited the highest affinity for the DnaA protein; the affinity of DnaA for the D78 cluster was about eightfold higher than the affinity for oriC. The high-affinity DnaA boxes appear to be involved in the control of chromosome replication. Deletion of D78 resulted in more frequent chromosome replication (an elevated ratio of origins to chromosome ends was observed) and activated aerial mycelium formation, leading to earlier colony maturation. In contrast, extra copies of D78 (delivered on a plasmid) caused slow colony growth, presumably because of a reduction in the frequency of initiation of chromosome replication. This suggests that the number of high-affinity DnaA boxes is relatively constant in hyphal compartments and that deletion of D78 therefore permits an increased copy number of either the chromosomal origin region or a plasmid harboring the D78 cluster. This system conceivably influences the timing of decisions to initiate aerial mycelial formation and sporulation.
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Affiliation(s)
- Aleksandra Smulczyk-Krawczyszyn
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
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22
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Abstract
The replication clamp PCNA and its loader RFC (Replication Factor C) are central factors required for processive replication and coordinated DNA repair. Recently, several additional related clamp loaders have been identified. These alternative clamp loaders contain the small Rfc2-5 subunits of RFC, but replace the large Rfc1 subunit by a pathway-specific alternative large subunit, Rad24 for the DNA damage checkpoint, Ctf18 for the establishment of sister chromatid cohesion, and Elg1 for a general function in chromosome stability. In order to define biochemical functions for these loaders, the loaders were overproduced in yeast and purified at a milligram scale. To aid in purification, the large subunit of each clamp loader was fused to a GST-tag that, after purification could be easily removed by a rhinoviral protease. This methodology yielded all clamp loaders in high yield and with high enzymatic activity. The yeast 9-1-1 checkpoint clamp, consisting of Rad17, Mec3, and Ddc1, was overproduced and purified in a similar manner.
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Affiliation(s)
- Göran O Bylund
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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23
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Abstract
The heterotrimeric checkpoint clamp comprises the Saccharomyces cerevisiae Rad17, Mec3, and Ddc1 subunits (Rad17/3/1, the 9-1-1 complex in humans). This DNA damage response factor is loaded onto DNA by the Rad24-RFC (replication factor C-like complex with Rad24) clamp loader and ATP. Although Rad24-RFC alone does not bind to naked partial double-stranded DNA, coating of the single strand with single-stranded DNA-binding protein RPA (replication protein A) causes binding of Rad24-RFC via interactions with RPA. However, RPA-mediated binding is abrogated when the DNA is coated with RPA containing a rpa1-K45E (rfa1-t11) mutation. These properties allowed us to determine the role of RPA in clamp-loading specificity. The Rad17/3/1 clamp is loaded with comparable efficiency onto naked primer/template DNA with either a 3'-junction or a 5'-junction. Remarkably, when the DNA was coated with RPA, loading of Rad17/3/1 at 3'-junctions was completely inhibited, thereby providing specificity to loading at 5'-junctions. However, Rad17/3/1 loaded at 5'-junctions can slide across double-stranded DNA to nearby 3'-junctions and thereby affect the activity of proteins that act at 3'-termini. These studies show a unique specificity of the checkpoint loader for 5'-junctions of RPA-coated DNA. The implications of this specificity for checkpoint function are discussed.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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24
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Zawilak-PAWLIK A, Kois A, Majka J, Jakimowicz D, Smulczyk-Krawczyszyn A, Messer W, Zakrzewska-Czerwińska J. Architecture of bacterial replication initiation complexes: orisomes from four unrelated bacteria. Biochem J 2005; 389:471-81. [PMID: 15790315 PMCID: PMC1175125 DOI: 10.1042/bj20050143] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacterial chromosome replication is mediated by single initiator protein, DnaA, that interacts specifically with multiple DnaA boxes located within the origin (oriC). We compared the architecture of the DnaA-origin complexes of evolutionarily distantly related eubacteria: two Gram-negative organisms, Escherichia coli and Helicobacter pylori, and two Gram-positive organisms, Mycobacterium tuberculosis and Streptomyces coelicolor. Their origins vary in size (from approx. 200 to 1000 bp) and number of DnaA boxes (from 5 to 19). The results indicate that: (i) different DnaA proteins exhibit various affinities toward single DnaA boxes, (ii) spatial arrangement of two DnaA boxes is crucial for the H. pylori and S. coelicolor DnaA proteins, but not for E. coli and M. tuberculosis proteins, and (iii) the oriC regions are optimally adjusted to their cognate DnaA proteins. The primary functions of multiple DnaA boxes are to determine the positioning and order of assembly of the DnaA molecules. Gradual transition from the sequence-specific binding of the DnaA protein to binding through co-operative protein-protein interactions seems to be a common conserved strategy to generate oligomeric initiator complexes bound to multiple sites within the chromosomal, plasmid and virial origins.
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Affiliation(s)
- Anna Zawilak-PAWLIK
- *Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
| | - Agnieszka Kois
- *Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
| | - Jerzy Majka
- †Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, U.S.A
| | - Dagmara Jakimowicz
- *Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
- ‡John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, U.K
| | - Aleksandra Smulczyk-Krawczyszyn
- *Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
| | - Walter Messer
- §Max-Planck-Institut für Molekulare Genetik, Berlin-Dahlem, Ihnenstrasse 73, D-14195 Germany
| | - Jolanta Zakrzewska-Czerwińska
- *Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wrocław, Poland
- To whom correspondence should be addressed (email )
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25
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Majka J, Burgers PM. Function of Rad17/Mec3/Ddc1 and its partial complexes in the DNA damage checkpoint. DNA Repair (Amst) 2005; 4:1189-94. [PMID: 16137930 DOI: 10.1016/j.dnarep.2005.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 07/18/2005] [Accepted: 07/20/2005] [Indexed: 11/18/2022]
Abstract
The Saccharomyces cerevisiae heterotrimeric checkpoint clamp consisting of the Rad17, Mec3, and Ddc1 subunits (Rad17/3/1, the 9-1-1 complex in humans) is an early response factor to DNA damage in a signal transduction pathway leading to the activation of the checkpoint system and eventually to cell cycle arrest. These subunits show structural similarities with the replication clamp PCNA and indeed, it was demonstrated in vitro that Rad17/3/1 could be loaded onto DNA by checkpoint specific clamp loader Rad24-RFC, analogous to the PCNA-RFC clamp-clamp loader system. We have studied the interactions between the checkpoint clamp subunits and the activity of partial clamp complexes. We find that none of the possible partial complexes makes up a clamp that can be loaded onto DNA by Rad24-RFC. In agreement, overexpression of DDC1 or RAD17 in a MEC3Delta strain, or of MEC3 or RAD17 in a DDC1Delta strain shows no rescue of damage sensitivity.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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26
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Abstract
DNA polymerase zeta (Pol zeta), a heterodimer of Rev3 and Rev7, is essential for DNA damage provoked mutagenesis in eukaryotes. DNA polymerases that function in a processive complex with the replication clamp proliferating cell nuclear antigen (PCNA) have been shown to possess a close match to the consensus PCNA-binding motif QxxLxxFF. This consensus motif is lacking in either subunit of Pol zeta, yet its activity is stimulated by PCNA. In particular, translesion synthesis of UV damage-containing DNA is dramatically stimulated by PCNA such that translesion synthesis rates are comparable with replication rates by Pol zeta on undamaged DNA. PCNA also stimulated translesion synthesis of a model abasic site by Pol zeta. Efficient PCNA stimulation required that PCNA was prevented from sliding off the damage-containing model oligonucleotide template-primer through the use of biotin-streptavidin bumpers or other blocks. Under those experimental conditions, facile bypass of the abasic site was also detected by DNA polymerase delta or eta (Rad30). The yeast DNA damage checkpoint clamp, consisting of Rad17, Mec3, and Ddc1, and an ortholog of human 9-1-1, has been implicated in damage-induced mutagenesis. However, this checkpoint clamp did not stimulate translesion synthesis by Pol zeta or by DNA polymerase delta.
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Affiliation(s)
- Parie Garg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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27
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Abstract
The DNA damage clamp loader replication factor C (RFC-Rad24) consists of the Rad24 protein and the four small Rfc2-5 subunits of RFC. This complex loads the heterotrimeric DNA damage clamp consisting of Rad17, Mec3, and Ddc1 (Rad17/3/1) onto partial duplex DNA in an ATP-dependent manner. Interactions between the clamp loader and the clamp have been proposed to mirror those of the replication clamp loader RFC and the sliding clamp proliferating cell nuclear antigen (PCNA). In that system, three ATP molecules bound to the Rfc2, Rfc3, and Rfc4 subunits are necessary and sufficient for efficient loading of PCNA, whereas ATP binding to Rfc1 is not required. In contrast, in this study, we show that mutant RFC-Rad24 with a rad24-K115E mutation in the ATP-binding domain of Rad24 shows defects in the ATPase of the complex and is defective for interaction with Rad17/3/1 and for loading of the checkpoint clamp. A similar defect was measured with a mutant RFC-Rad24 clamp loader carrying a rfc4K55R ATP-binding mutation, whereas the rfc4K55E clamp loader showed partial loading activity, in agreement with genetic studies of these mutants. These studies show that ATP utilization by the checkpoint clamp/clamp loader system is effectively different from that by the structurally analogous replication system.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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28
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Cieśla J, Majka J. [Responsibilities of enterprises introducing new dangerous chemical substances and preparations]. Med Pr 2004; 55:81-6. [PMID: 15156771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
The paper reviews the responsibilities of producers, importers and distributors set in a new Act of January 2001 on chemical substances and preparations (Off. J. 2001, No. 11, item 84, with subsequent amendments). This Act together with executive provisions is aimed at harmonizing Polish legislation with EU requirements. The Act sets conditions, restriction and bans of production placing on the market and use of chemical substances and preparations in order to protect human health and environment against their harmful effects. The Act together with a number of executive provisions render those who introduce dangerous chemicals and chemical preparations, including distributors responsible for: classification and labelling of dangerous chemical substances and preparations; possessing, making available and up-dating safety data sheets; supplying packages containing certain dangerous substances with child-proof fastenings; notifying the Inspector for Chemical Substances and Preparations about placing a dangerous preparation on the market; notifying the Inspector about a new substance and conducting required studies; being properly qualified to handle dangerous substances. The Act strictly defines the term "placing a substance or a preparation on the market"--it means making a substance or a preparation available to third parties on the territory of The Republic of Poland, territories of the Member States of the European Union or the territory of Iceland, Liechtenstein and Norway, unless the Act provides otherwise; it also means introduction of a substance or a preparation from outside of the territory referred to above on the customs territory of The Republic of Poland, or that of the member states of the European Union and other states listed above. In addition, some of the responsibilities defined by the provisions of the law on chemical substances and preparations are also applicable to handling of biocidals, which are classified as dangerous substances. The Act also defines the terms "substance" and "chemical preparation" and sets the rules for classification and labelling of dangerous chemical substances and preparations (criteria for classification, rules for labelling, introduces the official classification and labelling of certain substances in the "list of dangerous substances"). The Act identifies methods to be used in the tests of physico-chemical properties, toxicity and ecotoxicity of chemical substances and preparations to meet the legal requirements and sets criteria to be followed by institutions involved in such testing.
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Affiliation(s)
- Jacek Cieśla
- Biura do Spraw Substancji i Preparatów Chemicznych w Łodzi.
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Abstract
The proliferating cell nuclear antigen PCNA functions at multiple levels in directing DNA metabolic pathways. Unbound to DNA, PCNA promotes localization of replication factors with a consensus PCNA-binding domain to replication factories. When bound to DNA, PCNA organizes various proteins involved in DNA replication, DNA repair, DNA modification, and chromatin modeling. Its modification by ubiquitin directs the cellular response to DNA damage. The ring-like PCNA homotrimer encircles double-stranded DNA and slides spontaneously across it. Loading of PCNA onto DNA at template-primer junctions is performed in an ATP-dependent process by replication factor C (RFC), a heteropentameric AAA+ protein complex consisting of the Rfc1, Rfc2, Rfc3, Rfc4, and Rfc5 subunits. Loading of yeast PCNA (POL30) is mechanistically distinct from analogous processes in E. coli (beta subunit by the gamma complex) and bacteriophage T4 (gp45 by gp44/62). Multiple stepwise ATP-binding events to RFC are required to load PCNA onto primed DNA. This stepwise mechanism should permit editing of this process at individual steps and allow for divergence of the default process into more specialized modes. Indeed, alternative RFC complexes consisting of the small RFC subunits together with an alternative Rfc1-like subunit have been identified. A complex required for the DNA damage checkpoint contains the Rad24 subunit, a complex required for sister chromatid cohesion contains the Ctf18 subunit, and a complex that aids in genome stability contains the Elg1 subunit. Only the RFC-Rad24 complex has a known associated clamp, a heterotrimeric complex consisting of Rad17, Mec3, and Ddc1. The other putative clamp loaders could either act on clamps yet to be identified or act on the two known clamps.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Glinkowska M, Majka J, Messer W, Wegrzyn G. The mechanism of regulation of bacteriophage lambda pR promoter activity by Escherichia coli DnaA protein. J Biol Chem 2003; 278:22250-6. [PMID: 12654908 DOI: 10.1074/jbc.m212492200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apart from its function as an initiator of DNA replication, the Escherichia coli DnaA protein is also a specific transcription factor. It activates and represses a number of promoters. However, mechanisms of transcription stimulation by DnaA remained unknown. Bacteriophage lambda pR promoter is one of the promoters activated by DnaA. It was reported previously that DnaA binds downstream of the pR promoter and perhaps interacts with the RNA polymerase beta subunit. Here we demonstrate that DnaA positively regulates transcription from pR by stimulation of two steps in transcription initiation: RNA polymerase binding to the promoter region and promoter escape. For this transcription activation, two weak DnaA boxes located downstream of pR are necessary and sufficient. Such a mechanism of transcription activation and location of the activator-binding sites relative to the transcription start point are unusual in prokaryotes. Changes in the distance between the transcription start point and the first DnaA box by 5 and 10 bp and alterations in the orientation of these boxes did not abolish the stimulation of transcription by DnaA, but the efficiency of the promoter activation was different for various mutations. It seems plausible that formation of higher order nucleoprotein structures, involving DNA looping, is necessary for effective stimulation of the pR promoter. At high concentrations, DnaA is a repressor of pR rather than an activator. This repression was found to be because of inhibition of RNA polymerase binding to the promoter region.
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Affiliation(s)
- Monika Glinkowska
- Department of Molecular Biology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland
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31
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Abstract
The Saccharomyces cerevisiae Rad24 and Rad17 checkpoint proteins are part of an early response to DNA damage in a signal transduction pathway leading to cell cycle arrest. Rad24 interacts with the four small subunits of replication factor C (RFC) to form the RFC-Rad24 complex. Rad17 forms a complex with Mec3 and Ddc1 (Rad1731) and shows structural similarities with the replication clamp PCNA. This parallelism with a clamp-clamp loader system that functions in DNA replication has led to the hypothesis that a similar clamp-clamp loader relationship exists for the DNA damage response system. We have purified the putative checkpoint clamp loader RFC-Rad24 and the putative clamp Rad1731 from a yeast overexpression system. Here, we provide experimental evidence that, indeed, the RFC-Rad24 clamp loader loads the Rad1731 clamp around partial duplex DNA in an ATP-dependent process. Furthermore, upon ATP hydrolysis, the Rad1731 clamp is released from the clamp loader and can slide across more than 1 kb of duplex DNA, a process which may be well suited for a search for damage. Rad1731 showed no detectable exonuclease activity.
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Affiliation(s)
- Jerzy Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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Brzozowski T, Konturek PC, Konturek SJ, Schuppan D, Drozdowicz D, Kwiecień S, Majka J, Nakamura T, Hahn E. Effect of local application of growth factors on gastric ulcer healing and mucosal expression of cyclooxygenase-1 and -2. Digestion 2003; 64:15-29. [PMID: 11549833 DOI: 10.1159/000048835] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND/AIMS Ulcer healing involves expression of various growth factors such as epidermal growth factor (EGF), hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) at the ulcer margin, but the influence of EGF, HGF and bFGF applied locally with or without neutralizing anti-EGF, HGF and bFGF antibodies or cyclooxygenase (COX)-1 and COX-2 inhibitors on ulcer healing and the expression of COX-1 and COX-2 during ulcer healing have only been studied a little. METHODS Rats with gastric ulcers induced by serosal application of acetic acid (ulcer area 28 mm2 received a submucosal injection of either (1) vehicle (saline), (2) EGF, (3) HGF, and (4) bFGF with or without antibodies against EGF, HGF and bFGF or indomethacin (2 mg/kg/day i.p.), a nonspecific inhibitor of COX, or NS-398 (10 mg/kg/day i.g.) and Vioxx (5 mg/kg/day i.g.), both highly specific COX-2 inhibitors. A separate group of animals with chronic gastric fistulas was also used to assess gastric secretion during ulcer healing with and without growth factors. Each growth factor and specific antibody against EGF, HGF and bFGF (100 ng/100 microl each) were injected just around the ulcer immediately after ulcer induction and this local injection was repeated on day 2 following anesthesia and laparotomy. On days 13 and 21, the ulcer area was determined by planimetry, gastric blood flow (GBF) at the ulcer margin was examined by the H2-gas clearance technique, and mucosal generation of PGE2 and the gene expression of COX-1 and COX-2 in the non-ulcerated and ulcerated gastric mucosa were assessed. Gastric ulcers healed progressively within 21 days after induction and this effect was accompanied by a significant increase in GBF at the ulcer margin and in the expression of COX-2 in the ulcer area. Local treatment with EGF, HGF and bFGF produced a significant decrease in gastric acid secretion and significantly accelerated the rate of ulcer healing and raised GBF at the ulcer margin causing further significant upregulation of COX-2 but not COX-1 expression in the ulcerated mucosa. The acceleration of ulcer healing and hyperemia at the ulcer margin exhibited by locally applied EGF, HGF and bFGF were similar to those obtained with systemic administration of these growth factors. HGF applied submucosally, upregulated COX-2 expression and this was significantly attenuated by concurrent treatment with antibody against this peptide. Anti-EGF and anti-bFGF antibodies completely abolished the acceleration of the ulcer healing and hyperemia at the ulcer margin induced by these growth factors. Indomethacin and both COX-2 inhibitors significantly prolonged ulcer healing, while suppressing the generation of PGE2 in non-ulcerated and ulcerated gastric mucosa and GBF at the ulcer margin. The acceleration of ulcer healing by EGF, HGF and bFGF and the accompanying rise in GBF at the ulcer margin were significantly attenuated by the concurrent treatment with indomethacin or NS-398 and Vioxx. CONCLUSIONS (1) Growth factors accelerate ulcer healing due to enhancement in the microcirculation around the ulcer and these effects are specific because they can be abolished by neutralization with antibodies; (2) COX-2-derived prostaglandins and suppression of gastric secretion may play an important role in the acceleration of ulcer healing by various growth factors, and (3) the local effects of EGF, HGF and bFGF on ulcer healing can be reproduced by their systemic application indicating the high efficacy of growth factors to accelerate this healing.
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Affiliation(s)
- T Brzozowski
- Department of Physiology, Jagiellonian University School of Medicine, Cracow, Poland
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Xiao X, Wang F, Saito A, Majka J, Schlösser A, Schrempf H. The novel Streptomyces olivaceoviridis ABC transporter Ngc mediates uptake of N-acetylglucosamine and N,N'-diacetylchitobiose. Mol Genet Genomics 2002; 267:429-39. [PMID: 12111550 DOI: 10.1007/s00438-002-0640-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2001] [Accepted: 01/09/2002] [Indexed: 10/27/2022]
Abstract
During cultivation in the presence of N-acetylglucosamine or chitin, Streptomyces olivaceoviridis mycelium efficiently takes up [(14)C]-labelled N-acetylglucosamine. Uptake of the labelled compound can be completely inhibited by unlabelled N-acetylglucosamine and partially by chitobiose. After extraction of the membrane with Triton X-100, two forms of a protein that binds to N-acetylglucosamine and N, N'-diacetylchitobiose (chitobiose) were purified to homogeneity by two consecutive rounds of anionic exchange chromatography. The protein was named NgcE. Using surface plasmon resonance, its binding parameters were determined. It showed highest affinity for N-acetylglucosamine (K(D)=8.28 x 10(-9) M) and for chitobiose (K(D)=2.87 x 10(-8) M). Varying equilibrium dissociation constants in the micromolecular range were ascertained for chitotetraose (K(D)=4.5 x 10(-6) M), chitopentaose (K(D)=1.03 x 10(-6) M) and chitohexaose (K(D)=3.02 x 10(-6) M); the lowest value was measured for chitotriose (K(D)=19.4 x 10(-6) M). After having determined the sequences of several internal peptides from the binding protein by Edman degradation, the corresponding ngcE gene, which encodes a predicted lipid-anchored protein, was identified by reverse genetics. Using a genomic phage library of S. olivaceoviridis genes encoding two other membrane proteins (named NgcF and NgcG) were identified adjacent to ngcE. Each of these is predicted to have six membrane-spanning helices and a consensus motif for integral membrane proteins characteristic of ABC transporters. In addition, the gene for a predicted regulator protein (NgcR) was detected. The ngcEFG operon lacks a gene for an ATP-hydrolysing protein. NgcE is a new member of the CUT-1 family of ABC transporters for carbohydrates. Comparative studies of the wild-type and a mutant strain carrying an insertion within the ngc operon clearly demonstrate that the Ngc system mediates the uptake of N-acetylglucosamine and chitobiose in vivo.
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Affiliation(s)
- X Xiao
- Fachbereich Biologie/Chemie, Barbarastr. 11, D-49069 Osnabrück, Germany
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Abstract
DNA polymerase delta (Pol delta) from Saccharomyces cerevisiae consists of three subunits, Pol3 (125 kDa), Pol31 (55 kDa), and Pol32 (40 kDa), present at a 1:1:1 stoichiometry in purified preparations. Previously, based on gel filtration studies of Pol delta, we suggested that the enzyme may be a dimer of catalytic cores, with dimerization mediated by the Pol32 subunit (Burgers, P. M., and Gerik, K. J. (1998) J. Biol. Chem. 273, 19756-19762). We now report on extensive gel filtration, glycerol gradient sedimentation, and analytical equilibrium centrifugation studies of Pol delta and of several subassemblies of Pol delta. The hydrodynamic parameters of these assemblies indicate that (i) Pol32 is a rod-shaped protein with a frictional ratio f/f(0) = 2.22; (ii) any complex containing Pol32 also has an extremely asymmetric shape; (iii) the results of these studies are independent of concentration (varied between 0.1-20 microm); (iv) all complexes are monomeric under the conditions studied (up to 20 microm). Moreover, a two-hybrid analysis of the Pol32 subunit did not detect a Pol32-Pol32 interaction in vivo. Therefore, we conclude that the assembly structure of Pol delta is that of a monomer.
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Affiliation(s)
- E Johansson
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Majka J, Zakrzewska-Czerwiñska J, Messer W. Sequence recognition, cooperative interaction, and dimerization of the initiator protein DnaA of Streptomyces. J Biol Chem 2001; 276:6243-52. [PMID: 11073953 DOI: 10.1074/jbc.m007876200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using a combined PCR-gel retardation assay, the preferred recognition sequence of the Streptomyces initiator protein DnaA was determined. The protein showed a preference toward DNA containing two Escherichia coli-like DnaA boxes in a head-to-head arrangement (consensus sequence TTATCCACA, whereas the consensus sequence of the DnaA boxes found in the Streptomyces oriC region is TTGTCCACA). In quantitative band shift experiments, the kinetics of the Streptomyces DnaA-DnaA box interaction was characterized. The DnaA protein can form dimers while binding to a single DnaA box; dimer formation is mediated by the domain III of the protein, and the dissociation constant of this process was between 35 and 115 nm. Streptomyces initiator protein DnaA interacts in a cooperative manner with DNA containing multiple binding sites. For the cooperativity effect, which seems to be independent of the distance separating the DnaA boxes, domain I (or I and II) is responsible. The cooperativity constant is moderate and is in the range of 20-110.
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Affiliation(s)
- J Majka
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Weigla 12, 53-114 Wroclaw, Poland
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36
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Messer W, Blaesing F, Jakimowicz D, Krause M, Majka J, Nardmann J, Schaper S, Seitz H, Speck C, Weigel C, Wegrzyn G, Welzeck M, Zakrzewska-Czerwinska J. Bacterial replication initiator DnaA. Rules for DnaA binding and roles of DnaA in origin unwinding and helicase loading. Biochimie 2001; 83:5-12. [PMID: 11254968 DOI: 10.1016/s0300-9084(00)01216-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We review the processes leading to the structural modifications required for the initiation of replication in Escherichia coli, the conversion of the initial complex to the open complex, loading of helicase, and the assembly of two replication forks. Rules for the binding of DnaA to its binding sites are derived, and the properties of ATP-DnaA are described. We provide new data on cooperative interaction and dimerization of DnaA proteins of E. coli, Streptomyces and Thermus thermophilus, and on the stoichiometry of DnaA-oriC complexes of E. coli.
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Affiliation(s)
- W Messer
- Max-Planck-Institut für molekulare Genetik, Ihnestrasse 73, 14195, Berlin, Germany.
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Konturek SJ, Brzozowski T, Garlicki J, Majka J, Stachura J, Nauert C. Intragastric pH in the gastroprotective and ulcer-healing activity of aluminum-containing antacids. Digestion 2000; 49:140-50. [PMID: 1769429 DOI: 10.1159/000200713] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Antacids containing aluminum have been shown to stimulate the protective processes in the gastric mucosa and to enhance the healing of chronic gastroduodenal ulcerations, but the mechanisms of these effects are still unexplained. This study was designed to compare the protective effects of unmodified and acidified (pH 2.0) Maalox 70 and Al(OH)3 on the formation of acute gastric mucosal lesions induced by absolute ethanol, taurocholate, acidified aspirin and stress, and to determine the role of gastric acid in healing of chronic gastroduodenal ulcerations by these antacids in rats. Acidified Maalox 70 and Al(OH)3 were significantly more potent than unmodified agents against all four tested types of acute mucosal lesions, and this action was probably due to their 'mild irritant' effect as evidenced by extensive exfoliation of the surface epithelial cells observed microscopically after the exposure of the mucosa to these agents. Mucosal generation of prostaglandins does not appear to be involved in the gastroprotection by acidified Maalox because the pretreatment with indomethacin did not affect this protection. In contrast to the protective effect, the ulcer-healing capacity of Maalox or Al(OH)3 does not appear to be dependent upon the presence of gastric acid because the reduction or elimination of endogenous acid by the pretreatment with ranitidine or omeprazole did not affect the healing of gastroduodenal ulcerations. We conclude that aluminum-containing antacids induce the mucosal protection that is enhanced in the presence of luminal acid but exhibit an ulcer-healing property that appears to be unrelated to gastric acid secretion or mucosal generation of prostaglandins.
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Affiliation(s)
- S J Konturek
- Institute of Physiology, Academy of Medicine, Krakow, Poland
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39
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Osiadacz J, Majka J, Czarnecki K, Peczyńska-Czoch W, Zakrzewska-Czerwińska J, Kaczmarek L, Sokalski WA. Sequence-selectivity of 5,11-dimethyl-5H-indolo[2,3-b]quinoline binding to DNA. Footprinting and molecular modeling studies. Bioorg Med Chem 2000; 8:937-43. [PMID: 10882006 DOI: 10.1016/s0968-0896(00)00031-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Indolo[2,3-b]quinolines are a new family of the DNA intercalators showing significant cytotoxic activity. The mechanism of their action is based on the inhibition of DNA topoisomerase II activity. It depends on their ability to induce and stabilize drug-topII-DNA cleavable complexes. Site-specific intercalation of 5,11-dimethyl-5H-indolo[2,3-b]quinoline (DiMIQ) was analyzed in vitro by DNaseI footprinting and by molecular modeling. To model the DNA-intercalator complex, use was made of the CVFF and ESFF force fields implemented in Insight 97.0 software. Experimental results were verified using a simple statistical model. The DiMIQ molecule was found to bind preferentially to the pBR322 DNA plasmid in the 5'-TGCTAACGC-3' region between adjacent adenine bases.
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Affiliation(s)
- J Osiadacz
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław.
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Jakimowicz D, Majka J, Lis B, Konopa G, Wegrzyn G, Messer W, Schrempf H, Zakrzewska-Czerwinska J. Structure and regulation of the dnaA promoter region in three Streptomyces species. Mol Gen Genet 2000; 262:1093-102. [PMID: 10660070 DOI: 10.1007/pl00008652] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The regulatory region of the Streptomyces dnaA gene comprises a single promoter and two DnaA boxes that are located upstream of the promoter. Comparative analysis of the dnaA promoter region from S. chrysomallus, S. lividans and S. reticuli revealed that the location, spacing and orientation of the DnaA boxes are conserved. In vitro studies demonstrated that efficient binding of the Streptomyces DnaA protein to DNA requires the presence of two DnaA boxes. In vivo analysis of dnaA promoter mutants deleted for one or both DnaA boxes indicated that the dnaA gene is autoregulated. However, the degree of derepression observed is relatively modest.
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Affiliation(s)
- D Jakimowicz
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw
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Messer W, Blaesing F, Majka J, Nardmann J, Schaper S, Schmidt A, Seitz H, Speck C, Tüngler D, Wegrzyn G, Weigel C, Welzeck M, Zakrzewska-Czerwinska J. Functional domains of DnaA proteins. Biochimie 1999; 81:819-25. [PMID: 10572294 DOI: 10.1016/s0300-9084(99)00215-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Functional domains of the initiator protein DnaA of Escherichia coli have been defined. Domain 1, amino acids 1-86, is involved in oligomerization and in interaction with DnaB. Domain 2, aa 87-134, constitutes a flexible loop. Domain 3, aa 135-373, contains the binding site for ATP or ADP, the ATPase function, a second interaction site with DnaB, and is required for local DNA unwinding. Domain 4 is required and sufficient for specific binding to DNA. We show that there are three different types of cooperative interactions during the DNA binding of DnaA proteins from E. coli, Streptomyces lividans, and Thermus thermophilus: i) binding to distant binding sites; ii) binding to closely spaced binding sites; and iii) binding to non-canonical binding sites.
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Affiliation(s)
- W Messer
- Max-Planck-Institut für molekulare Genetik, Ihnestrasse 73, 14195 Berlin-Dahlem, Germany
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42
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Majka J, Jakimowicz D, Messer W, Schrempf H, Lisowski M, Zakrzewska-Czerwińska J. Interactions of the Streptomyces lividans initiator protein DnaA with its target. Eur J Biochem 1999; 260:325-35. [PMID: 10095766 DOI: 10.1046/j.1432-1327.1999.00168.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Streptomyces lividans DnaA protein (73 kDa) consists, like other bacterial DnaA proteins, of four domains; it binds to 19 DnaA boxes in the complex oriC region. The S. lividans DnaA protein differs from others in that it contains an additional stretch of 120 predominantly acidic amino acids within domain II. Interactions between the DnaA protein and the two DnaA boxes derived from the promoter region of the S. lividans dnaA gene were analysed in vitro using three independent methods: Dnase-I-footprinting experiments, mobility-shift assay and surface plasmon resonance (SPR). The Dnase-I-footprinting analysis showed that the wild-type DnaA protein binds to both DnaA boxes. Thus, as in Escherichia coli and Bacillus subtilis, the S. lividans dnaA gene may be autoregulated. SPR analysis showed that the affinity of the DnaA protein for a DNA fragment containing both DnaA boxes from the dnaA promoter region (KD = 1.25 nM) is 10 times higher than its affinity for the single 'strong' DnaA box (KD = 12.0 nM). The mobility-shift assay suggests the presence of at least two classes of complex containing different numbers of bound DnaA molecules. The above data reveal that the DnaA protein binds to the two DnaA boxes in a cooperative manner. To deduce structural features of the Streptomyces domain II of DnaA protein, the amino acid DnaA sequences of three Streptomyces species were compared. However, according to the secondary structure prediction, Streptomyces domain II does not contain any common relevant secondary structural element(s). It can be assumed that domain II of DnaA protein can play a role as a flexible protein spacer between the N-terminal domain I and the highly conserved C-terminal part of DnaA protein containing ATP-binding domain III and DNA-binding domain IV.
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Affiliation(s)
- J Majka
- Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
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Jakimowicz D, Majka J, Messer W, Speck C, Fernandez M, Cruz Martin M, Sanchez J, Schauwecker F, Keller U, Schrempf H, Zakrzewska-Czerwinńska J. Structural elements of the Streptomyces oriC region and their interactions with the DnaA protein. Microbiology (Reading) 1998; 144 ( Pt 5):1281-1290. [PMID: 9611803 DOI: 10.1099/00221287-144-5-1281] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptomycetes differ from other prokaryotic organisms in their mycelial life cycle and in possessing a large, linear, GC-rich chromosome. To deduce structural features of the Streptomyces origin of chromosomal replication, the oriC sequences of three Streptomyces species (S. antibioticus, S. chrysomallus and S. lividans) were compared. In Streptomyces, the oriC region contains 19 DnaA boxes whose location, orientation and spacing are conserved. The consensus sequence of the DnaA box identified within Streptomyces oriC is (T/C)(T/C)(G/A/C)TCCACA (preferred bases underlined). The interactions of DnaA with DNA fragments containing single, two or three DnaA boxes were studied using surface plasmon resonance. The dissociation constant (KD) for specific binding of individual DnaA boxes varied between 12 and 78 nM. Streptomyces oriC does not contain the three AT-rich 13-mer direct repeats present in the 5' part of the Escherichia coli oriC region. However, short AT-rich sequences are distributed among the DnaA boxes of Streptomyces oriC. Repeated attempts to unwind Streptomyces oriC have been unsuccessful. It remains to be elucidated whether DnaA interacts with putative accessory proteins which help in unwinding Streptomyces oriC.
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Affiliation(s)
- Dagmara Jakimowicz
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wroclaw, Poland
| | - Jerzy Majka
- Max-Planck-Institut für Molekulare Genetik, Ihnestraße 73, D-14195 Berlin-Dahlem, Germany
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wroclaw, Poland
| | - Walter Messer
- Max-Planck-Institut für Molekulare Genetik, Ihnestraße 73, D-14195 Berlin-Dahlem, Germany
| | - Christian Speck
- Max-Planck-Institut für Molekulare Genetik, Ihnestraße 73, D-14195 Berlin-Dahlem, Germany
| | - Marisol Fernandez
- Departamento de Biologia Funcional e Instituto Universitario de Biotecnologia de Asturias, Universidad de Oviedo, J. Claveria 6, Oviedo 33006, Spain
| | - M Cruz Martin
- Departamento de Biologia Funcional e Instituto Universitario de Biotecnologia de Asturias, Universidad de Oviedo, J. Claveria 6, Oviedo 33006, Spain
| | - Jesus Sanchez
- Departamento de Biologia Funcional e Instituto Universitario de Biotecnologia de Asturias, Universidad de Oviedo, J. Claveria 6, Oviedo 33006, Spain
| | - Florian Schauwecker
- Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Fachgebiet Biochemie und Molekulare Biologie, Technische Universität Berlin, Franklinstrasse 29, D-10587 Berlin, Germany
| | - Ullrich Keller
- Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Fachgebiet Biochemie und Molekulare Biologie, Technische Universität Berlin, Franklinstrasse 29, D-10587 Berlin, Germany
| | - Hildgund Schrempf
- Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastraße 11, 49069 Osnabrück, Germany
| | - Jolanta Zakrzewska-Czerwinńska
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wroclaw, Poland
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Majka J, Jakimowicz D, Zarko-Postawka M, Zakrzewska-Czerwinska J. Glutathione S-transferase fusion proteins as an affinity reagent for rapid isolation of specific sequence directly from genomic DNA. Nucleic Acids Res 1997; 25:2537-8. [PMID: 9171112 PMCID: PMC146755 DOI: 10.1093/nar/25.12.2537] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We describe a DNA binding assay for isolation of specific sequence(s) recognized by protein of interest directly from genomic or cosmid DNA. In our assay, the protein is fused to the glutathione-S-transferase and bound to glutathione-Sepharose beads. Then the immobilized fusion protein can be used to search for DNA fragment(s) that interact specifically with the protein of interest. As an example of such an approach, we identified and cloned a few prokaryotic oriC regions using the initiator DnaA protein fused to the glutathione-S-transferase.
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Affiliation(s)
- J Majka
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. Weigla 12, 53-114 Wroclaw, Poland
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Abstract
The Streptomyces lividans DnaA protein (73 kDa) consists, like the Escherichia coli DnaA protein (52 kDa), of four domains. The larger size of the S. lividans protein is due to an additional stretch of 120 predominantly acidic amino acids within domain II. The S. lividans protein was overproduced as a His-tagged fusion protein. The purified protein (isoelectric point, 5.7) has a weak ATPase activity. By DNase I footprinting studies, each of the 17 DnaA boxes (consensus sequence, TTGTCCACA) in the S. lividans oriC region was found to be protected by the DnaA fusion protein. Purified mutant proteins carrying a deletion of the C-terminally located helix-loop-helix (HLH) motif or with amino acid substitutions in helix A (L577G) or helix B (R595A) no longer interact with DnaA boxes. A substitution of basic amino acids in the loop of the HLH motif (R587A or R589A) entailed the formation of S. lividans mutant DnaA proteins with little or no capacity for binding to DnaA boxes. Thus, like in E. coli, the C-terminally located domain IV is absolutely necessary for the specific binding of DnaA. A mutant protein lacking a stretch of acidic amino acids corresponding to domain II is not affected in its DNA binding capacity. Whether the acidic domain II interacts with accessory proteins remains to be elucidated.
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Affiliation(s)
- J Majka
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw
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Konturek PC, Konturek SJ, Majka J, Zembala M, Hahn EG. Melatonin affords protection against gastric lesions induced by ischemia-reperfusion possibly due to its antioxidant and mucosal microcirculatory effects. Eur J Pharmacol 1997; 322:73-7. [PMID: 9088873 DOI: 10.1016/s0014-2999(97)00051-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Melatonin, a pineal hormone, is known to scavenge oxygen free radicals and to be present in the gut but little is known about its role in the protection of gastric mucosa against the damage accompanied by a marked increase in these radicals. This study was designed to determine the effects of melatonin on the formation of acute gastric lesions induced by ischemia-reperfusion and, for comparison, by a topical irritant such as 100% ethanol. It was found that pretreatment with melatonin at a dose of 5 mg/kg given intragastrically reduced significantly gastric lesions induced by ischemia-reperfusion and this was accompanied by a reduction in free radicals in the blood and by attenuation of the fall in gastric blood flow. In contrast, melatonin failed to affect acute gastric lesions induced by 100% ethanol. We conclude that melatonin is capable of protecting gastric mucosa from the damage caused by ischemia-reperfusion and that this action is mediated, at least in part, by limitation of the generation of free radicals and by attenuation of the fall in gastric blood flow.
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Affiliation(s)
- P C Konturek
- Department of Physiology, Jagiellonian University School of Medicine, Kraków, Poland
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47
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Brzozowski T, Sliwowski Z, Majka J, Drozdowicz D, Konturek SJ. Urea-urease system in cytoprotection against acute mucosal damage. J Physiol Pharmacol 1996; 47:137-50. [PMID: 8777294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ammonia (NH4OH) generated by urease from urea in the Helicobacter pylori (Hp)-infected stomach is considered as a one of the major pathogenic factors in the Hp-associated gastritis but the mechanism of the deleterious action of NH4OH on gastric mucosa has not been fully explained. In this study, the gastric mucosa was exposed to topical NH4OH in various concentrations (15-250 mM) (series A) and to NH4OH in a small concentration followed by a high concentration (250 mM) of NH4OH (series B) or to the combination of urea and urease to generate NH4OH (series C) followed by 250 mM NH4OH in order to determine the "mild irritant" and protective properties of this substance on the mucosa. Administration of NH4OH alone resulted in a concentration-dependent mucosal damage starting at 30 mM and reaching at 250 mM the degree similar to that obtained with 100% ethanol. The acute mucosal damage by NH4OH was accompanied by the fall in gastric blood flow reaching nadir at 250 mM NH4OH of about 30% of the normal value. When the mucosa was first exposed to low concentration of NH4OH (15 mM) and then insulted with its larger concentration (250 mM), the lesion area was markedly reduced as compared to that obtained with 250 mM NH4OH alone and this effect was accompanied by a significant rise in the GBF. This adaptive cytoprotection by 15 mM NH4OH was reversed, in part, by the pretreatment with indomethacin to inhibit prostaglandins (PG) or L-NAME to suppress nitric oxide (NO) formation or after capsaicin-induced denervation of sensory nerves. Blockade of endogenous sulfhydryls (SH) by N-ethylmaleimide (NEM) eliminated this adaptive cytoprotection but the suppression of ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, by alpha-difluoro methylornithine (DFMO) failed to influence the protection and accompanying hyperemia afforded by NH4OH in low concentration. The combination of urea (2%) and urease (100 U), which raised the gastric luminal NH4OH concentration by about 5-folds, also reduced significantly the lesions provoked by 250 mM NH4OH. This protection and accompanying hyperemia induced was significantly attenuated by the pretreatment with indomethacin or hydroxyurea, a potent urease inhibitor. Hydroxyurea abolished completely the rise in luminal NH4OH produced by the combined treatment of urea plus urease. We conclude that 1) NH4OH in high concentration damages the gastric mucosa but when applied at lower concentration or generated in the stomach by urea-urease system, acts as local mild irritant to induce adaptive cytoprotection that probably involves PG, sensory nerves and arginine-NO-pathaway.
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Affiliation(s)
- T Brzozowski
- Institute of Physiology, Jagiellonian University School of Medicine, Cracow, Poland
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Slomiany BL, Piotrowski J, Majka J, Czajkowski A, Slomiany A, Gabryelewicz A. Enhancement in the protective qualities of gastric mucus by ebrotidine during duodenal ulcer healing. Gen Pharmacol 1995; 26:1039-44. [PMID: 7557247 DOI: 10.1016/0306-3623(94)00291-t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
1. Gastric mucus from duodenal ulcer patients before and following therapy with a new antiulcer agent, ebrotidine, at 400, 600 and 800 mg dose was examined for changes in the physicochemical qualities and anti-H. pylori activity. 2. The results of physical measurements revealed that successful therapy with ebrotidine was accompanied by a 25% increase in gastric mucus viscosity, and a 20% increase in H+ retardation capacity, while its hydrophobicity increased by 11%. 3. The enhancement in the physical properties of mucus with ebrotidine therapy were also reflected in a marked (2.6-2.9-fold) increase in the proportion of the high molecular weight form of mucin. Furthermore, following therapy with ebrotidine, the gastric mucins showed a 36% higher content of sulfate as compared to that before the therapy. 4. Assays on the H. pylori aggregating titer of gastric mucin revealed that ebrotidine therapy at all three doses evoked a 4-fold increase in mucin anti-H. pylori activity. 5. The data demonstrate that duodenal ulcer therapy with ebrotidine leads to a marked improvement in the protective qualities of gastric mucus essential for the maintenance of mucosal integrity and enhances the inherent mucosal defense against H. pylori infection.
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Affiliation(s)
- B L Slomiany
- Research Center, University of Medicine and Dentistry of New Jersey, Newark, USA
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Zakrzewska-Czerwińska J, Majka J, Schrempf H. Minimal requirements of the Streptomyces lividans 66 oriC region and its transcriptional and translational activities. J Bacteriol 1995; 177:4765-71. [PMID: 7642504 PMCID: PMC177243 DOI: 10.1128/jb.177.16.4765-4771.1995] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Deletion analysis of a previously constructed minichromosome revealed that a stretch of DNA which is longer than 623 bp but shorter than 837 bp is required for autonomous replication of the Streptomyces lividans chromosome. Each of the dnaA and dnaN genes flanking the oriC region is individually transcribed from two promoters. Within the intergenic, nontranslatable region between the dnaA and dnaN genes, five main transcripts and several less abundant transcripts of various lengths as well as one of the promoters were identified. The introduction of additional DnaA boxes in S. lividans led to a significant increase in dnaA gene transcripts and to an enhanced level of the DnaA (73-kDa) protein. In summary, the data suggest that dnaA gene transcription is autoregulated and that initiation of the S. lividans chromosome is tightly controlled.
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Affiliation(s)
- J Zakrzewska-Czerwińska
- Department of Microbiology, Institute of Immunology and Experimental Therapy, Wrocław, Poland
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Piotrowski J, Majka J, Sano S, Nowak P, Murty VL, Slomiany A, Slomiany BL. Enhancement in gastric mucosal EGF and PDGF receptor expression with ulcer healing by sulglycotide. Gen Pharmacol 1995; 26:749-53. [PMID: 7635250 DOI: 10.1016/0306-3623(94)00261-k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. The effect of an antiulcer agent, sulglycotide, on mucosal expression of EGF and PDGF receptors with chronic ulcer healing was investigated. 2. Rats with experimentally-induced gastric ulcers were treated twice daily for 14 consecutive days, either with sulglycotide at 200 mg/kg or vehicle, and at different stages of treatment used for quantitation of gastric mucosal EGF and PDGF receptors. 3. The ulcer healing was accompanied by an increase in mucosal expression of both types of receptors. A 1.8-fold increase in EGF and 3.1-fold increase in PDGF receptors occurred by the 4th day following the development of ulcer and reached a maximum of 2.4-3.9-fold increase by the 10-14th day. 4. Treatment with sulglycotide caused accelerated ulcer healing accompanied by a significant enhancement in the receptors expression. A 2.3- and 3.6-fold increase in EGF and PDGF receptor expression occurred by the 4th day of sulglycotide treatment, reaching a 5.5- and 5.6-fold respective increase by the 10th day when the ulcer essentially healed. 5. The results attest to the ability of sulglycotide to stimulate the gastric mucosal proliferative activities associated with ulcer healing.
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Affiliation(s)
- J Piotrowski
- Research Center, University of Medicine and Dentistry of New Jersey, Newark 07103-2400, USA
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