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Indla E, Rajasekar KV, Naveen Kumar B, Kumar SS, P UK, Sayana SB. Modulation of Oxidative Stress and Glycemic Control in Diabetic Wistar Rats: The Therapeutic Potential of Theobroma cacao and Camellia sinensis Diets. Cureus 2024; 16:e55985. [PMID: 38606255 PMCID: PMC11007453 DOI: 10.7759/cureus.55985] [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: 12/03/2023] [Accepted: 03/11/2024] [Indexed: 04/13/2024] Open
Abstract
Background Diabetes mellitus is a complex metabolic disorder characterized by oxidative stress and impaired glycemic control. This study investigates the therapeutic potential of Theobroma cacao and Camellia sinensis diets in diabetic Wistar rats and assesses their impact on oxidative stress markers and blood glucose levels. Methods In this experiment, eight groups of six male Wistar rats (n = 12.5%), aged 8 to 12 weeks, were carefully set up to see how different treatments for diabetes and oxidative stress affected the two conditions. The random selection process was implemented to minimize any potential bias and ensure that the results of the study would be representative of the general population of Wistar rats. The groups were as follows: a nondiabetic control group (NDC) served as the baseline, while diabetes was induced in the alloxan monohydrate group (150 mg/kg). Another group was given the standard drug metformin (M, 100 mg/kg), and two control groups that did not have diabetes were given extracts of Theobroma cacao (TC, 340 mg/kg) and Camellia sinensis (CS, 200 mg/kg). Three groups of diabetic rats were given a mix of these treatments. Theobroma cacao and Camellia sinensis extracts were given at set doses (TC, 340 mg/kg; CS, 200 mg/kg), along with 150 mg/kg of a drug that causes diabetes. Over a 21-day period, oxidative stress parameters such as glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione reductase (GSHrd) levels, and blood glucose were carefully measured to check for signs of oxidative stress and diabetes progression Results Considerable differences in GSH levels were noted across the groups, with the highest GSH concentration found in the group treated with the inducing drug, while the lowest GSH levels were observed in the diabetic group that was administered both Theobroma cacao and Camellia sinensis (p < 0.001). MDA levels also varied, with the diabetic group treated with Theobroma cacao having the highest MDA concentration (3.54 ± 0.29 μmol/L) and the nondiabetic control group treated with Camellia sinensis exhibiting the lowest MDA levels (1.66 ± 0.08 μmol/L; p < 0.001). SOD activity was highest in the standard drug group and lowest in the diabetic group treated with Theobroma cacao. GSH activity was notably higher in the diabetic groups that received dietary interventions (p < 0.001). Blood glucose levels showed diverse responses, with the standard drug group experiencing a substantial reduction, while the inducing drug group exhibited a consistent increase. Conclusion The study highlights the significant impact of dietary interventions with Theobroma cacao and Camellia sinensis on oxidative stress markers and blood glucose regulation in diabetic Wistar rats. These findings suggest a potential role for these dietary components in mitigating oxidative stress and improving glycemic control in diabetes, although further research is warranted to elucidate the underlying mechanisms and clinical implications.
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Affiliation(s)
- Edward Indla
- Department of Anatomy, Meenakshi Academy of Higher Education and Research, Chennai, IND
| | - K V Rajasekar
- Department of Radiology, Meenakshi Medical College Hospital and Research Institute, Chennai, IND
| | | | - S Saravana Kumar
- Department of Anatomy, Meenakshi Medical College Hospital and Research Institute, Chennai, IND
| | - Udaya Kumar P
- Department of Anatomy, Mamata Medical College, Khammam, IND
| | - Suresh Babu Sayana
- Department of Pharmacology, Government Medical College and General Hospital, Suryapet, IND
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Fisher GL, Bolla JR, Rajasekar KV, Mäkelä J, Baker R, Zhou M, Prince JP, Stracy M, Robinson CV, Arciszewska LK, Sherratt DJ. Competitive binding of MatP and topoisomerase IV to the MukB hinge domain. eLife 2021; 10:70444. [PMID: 34585666 PMCID: PMC8523169 DOI: 10.7554/elife.70444] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 05/17/2021] [Accepted: 09/21/2021] [Indexed: 11/13/2022] Open
Abstract
Structural Maintenance of Chromosomes (SMC) complexes have ubiquitous roles in compacting DNA linearly, thereby promoting chromosome organization-segregation. Interaction between the Escherichia coli SMC complex, MukBEF, and matS-bound MatP in the chromosome replication termination region, ter, results in depletion of MukBEF from ter, a process essential for efficient daughter chromosome individualization and for preferential association of MukBEF with the replication origin region. Chromosome-associated MukBEF complexes also interact with topoisomerase IV (ParC2E2), so that their chromosome distribution mirrors that of MukBEF. We demonstrate that MatP and ParC have an overlapping binding interface on the MukB hinge, leading to their mutually exclusive binding, which occurs with the same dimer to dimer stoichiometry. Furthermore, we show that matS DNA competes with the MukB hinge for MatP binding. Cells expressing MukBEF complexes that are mutated at the ParC/MatP binding interface are impaired in ParC binding and have a mild defect in MukBEF function. These data highlight competitive binding as a means of globally regulating MukBEF-topoisomerase IV activity in space and time.
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Affiliation(s)
- Gemma Lm Fisher
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Jani R Bolla
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom.,The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom
| | | | - Jarno Mäkelä
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Rachel Baker
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Man Zhou
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Josh P Prince
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mathew Stracy
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom.,The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom
| | | | - David J Sherratt
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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3
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Rajasekar KV, Baker R, Fisher GLM, Bolla JR, Mäkelä J, Tang M, Zawadzka K, Koczy O, Wagner F, Robinson CV, Arciszewska LK, Sherratt DJ. Dynamic architecture of the Escherichia coli structural maintenance of chromosomes (SMC) complex, MukBEF. Nucleic Acids Res 2019; 47:9696-9707. [PMID: 31400115 PMCID: PMC6765140 DOI: 10.1093/nar/gkz696] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/23/2019] [Accepted: 07/31/2019] [Indexed: 12/18/2022] Open
Abstract
Ubiquitous Structural Maintenance of Chromosomes (SMC) complexes use a proteinaceous ring-shaped architecture to organize and individualize chromosomes, thereby facilitating chromosome segregation. They utilize cycles of adenosine triphosphate (ATP) binding and hydrolysis to transport themselves rapidly with respect to DNA, a process requiring protein conformational changes and multiple DNA contact sites. By analysing changes in the architecture and stoichiometry of the Escherichia coli SMC complex, MukBEF, as a function of nucleotide binding to MukB and subsequent ATP hydrolysis, we demonstrate directly the formation of dimer of MukBEF dimer complexes, dependent on dimeric MukF kleisin. Using truncated and full length MukB, in combination with MukEF, we show that engagement of the MukB ATPase heads on nucleotide binding directs the formation of dimers of heads-engaged dimer complexes. Complex formation requires functional interactions between the C- and N-terminal domains of MukF with the MukB head and neck, respectively, and MukE, which organizes the complexes by stabilizing binding of MukB heads to MukF. In the absence of head engagement, a MukF dimer bound by MukE forms complexes containing only a dimer of MukB. Finally, we demonstrate that cells expressing MukBEF complexes in which MukF is monomeric are Muk−, with the complexes failing to associate with chromosomes.
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Affiliation(s)
- Karthik V Rajasekar
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Rachel Baker
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Gemma L M Fisher
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Jani R Bolla
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Jarno Mäkelä
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Minzhe Tang
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Katarzyna Zawadzka
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Oliwia Koczy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Florence Wagner
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Carol V Robinson
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Lidia K Arciszewska
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - David J Sherratt
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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Coulthard RJ, Rajasekar KV, Ride JP, Hyde EI, Smith LJ. 1H, 13C and 15N NMR assignments of self-incompatibility protein homologue 15 from Arabidopsis thaliana. Biomol NMR Assign 2019; 13:67-70. [PMID: 30284185 PMCID: PMC6439154 DOI: 10.1007/s12104-018-9853-0] [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] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/28/2018] [Indexed: 06/08/2023]
Abstract
The SPH proteins are a large family of small, disulphide-bonded, secreted proteins, originally found to be involved in the self-incompatibility response in the field poppy (Papaver rhoeas). They are now known to be widely distributed in plants, many containing multiple members of this protein family. Apart from the PrsS proteins in Papaver the function of these proteins is unknown but they are thought to be involved in plant development and cell signalling. There has been no structural study of SPH proteins to date. Using the Origami strain of E. coli, we cloned and expressed one member of this family, SPH15 from Arabidopsis thaliana, as a folded thioredoxin-fusion protein, purified it from the cytosol, and cleaved it to obtain the secreted protein. We here report the assignment of the NMR spectra of SPH15, which contains 112 residues plus three N-terminal amino acids from the vector. The secondary structure propensity from TALOS+ shows that it contains eight beta strands and connecting loops. This is largely in agreement with predictions from the amino acid sequence, which show an additional C-terminal strand.
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Affiliation(s)
- Rachel J. Coulthard
- Department of Chemistry, University of Oxford, Oxford, OX1 3QR UK
- Present Address: EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | | | - Jon P. Ride
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT UK
| | - Eva I. Hyde
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT UK
| | - Lorna J. Smith
- Department of Chemistry, University of Oxford, Oxford, OX1 3QR UK
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Zawadzka K, Zawadzki P, Baker R, Rajasekar KV, Wagner F, Sherratt DJ, Arciszewska LK. MukB ATPases are regulated independently by the N- and C-terminal domains of MukF kleisin. eLife 2018; 7:31522. [PMID: 29323635 PMCID: PMC5812716 DOI: 10.7554/elife.31522] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [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: 08/24/2017] [Accepted: 01/10/2018] [Indexed: 12/21/2022] Open
Abstract
The Escherichia coli SMC complex, MukBEF, acts in chromosome segregation. MukBEF shares the distinctive architecture of other SMC complexes, with one prominent difference; unlike other kleisins, MukF forms dimers through its N-terminal domain. We show that a 4-helix bundle adjacent to the MukF dimerisation domain interacts functionally with the MukB coiled-coiled ‘neck’ adjacent to the ATPase head. We propose that this interaction leads to an asymmetric tripartite complex, as in other SMC complexes. Since MukF dimerisation is preserved during this interaction, MukF directs the formation of dimer of dimer MukBEF complexes, observed previously in vivo. The MukF N- and C-terminal domains stimulate MukB ATPase independently and additively. We demonstrate that impairment of the MukF interaction with MukB in vivo leads to ATP hydrolysis-dependent release of MukBEF complexes from chromosomes. Most DNA in a cell is arranged in structures called chromosomes. From bacteria to humans, chromosomes have to be compacted and highly organized to allow the cells to maintain and use their genetic information. In all organisms, large ring-shaped protein complexes play a crucial role in managing chromosomes. They transport and organize DNA thanks to reactions whose precise mechanism remains unknown. In bacteria, MukB and a type of kleisin called MukF are two examples of molecules involved in chromosome management. Two MukBs join at one end to form a hinge; at the other end, each MukB protein has a neck and a head. The two heads are linked by the kleisin to form a large protein ring, which can open to capture DNA. The MukB heads can trigger a biochemical reaction that creates the energy essential to trap and release DNA during DNA transport. Here, Zawadzka et al. study how the different components of the MukB-kleisin complex interact with each other to undergo the biochemical reactions that lead to DNA transport. The experiments show that the kleisin joins two MukB heads by attaching the base of one to the neck of the other, asymmetrically closing the ring. The separate interactions of different regions of the kleisin to the head and neck of MukB independently activate the two MukB heads, thereby controlling essential steps in the reactions with DNA. Two MukB-kleisin ring complexes are joined to each other because of a tight interaction between the two kleisin molecules. This leads Zawadzka et al. to suggest that DNA is sequentially grabbed and released from these two rings during DNA transport, similar to how a climbing rope is attached and released through carabiners. Cells cannot survive or be healthy without their chromosomes being accurately managed. It is still unclear how molecules such as MukBs and kleinsins drive this process. A better picture of their structure and interactions is an essential first step to understand these mechanisms.
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Affiliation(s)
- Katarzyna Zawadzka
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Pawel Zawadzki
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Rachel Baker
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | | | - Florence Wagner
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - David J Sherratt
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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6
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Hyde EI, Callow P, Rajasekar KV, Timmins P, Patel TR, Siligardi G, Hussain R, White SA, Thomas CM, Scott DJ. Intrinsic disorder in the partitioning protein KorB persists after co-operative complex formation with operator DNA and KorA. Biochem J 2017; 474:3121-3135. [PMID: 28760886 PMCID: PMC5577506 DOI: 10.1042/bcj20170281] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 07/26/2017] [Accepted: 07/31/2017] [Indexed: 11/24/2022]
Abstract
The ParB protein, KorB, from the RK2 plasmid is required for DNA partitioning and transcriptional repression. It acts co-operatively with other proteins, including the repressor KorA. Like many multifunctional proteins, KorB contains regions of intrinsically disordered structure, existing in a large ensemble of interconverting conformations. Using NMR spectroscopy, circular dichroism and small-angle neutron scattering, we studied KorB selectively within its binary complexes with KorA and DNA, and within the ternary KorA/KorB/DNA complex. The bound KorB protein remains disordered with a mobile C-terminal domain and no changes in the secondary structure, but increases in the radius of gyration on complex formation. Comparison of wild-type KorB with an N-terminal deletion mutant allows a model of the ensemble average distances between the domains when bound to DNA. We propose that the positive co-operativity between KorB, KorA and DNA results from conformational restriction of KorB on binding each partner, while maintaining disorder.
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Affiliation(s)
- Eva I Hyde
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K.
| | - Philip Callow
- Institut Laue Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | | | - Peter Timmins
- Institut Laue Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Trushar R Patel
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K
| | - Giuliano Siligardi
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Rohanah Hussain
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Scott A White
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K
| | | | - David J Scott
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, U.K.
- ISIS Neutron and Muon Spallation Source and Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, U.K
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Rajasekar KV, Lovering AL, Dancea F, Scott DJ, Harris SA, Bingle LEH, Roessle M, Thomas CM, Hyde EI, White SA. Flexibility of KorA, a plasmid-encoded, global transcription regulator, in the presence and the absence of its operator. Nucleic Acids Res 2016; 44:4947-56. [PMID: 27016739 PMCID: PMC4889941 DOI: 10.1093/nar/gkw191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 03/08/2016] [Accepted: 03/11/2016] [Indexed: 12/03/2022] Open
Abstract
The IncP (Incompatibility group P) plasmids are important carriers in the spread of antibiotic resistance across Gram-negative bacteria. Gene expression in the IncP-1 plasmids is stringently controlled by a network of four global repressors, KorA, KorB, TrbA and KorC interacting cooperatively. Intriguingly, KorA and KorB can act as co-repressors at varying distances between their operators, even when they are moved to be on opposite sides of the DNA. KorA is a homodimer with the 101-amino acid subunits, folding into an N-terminal DNA-binding domain and a C-terminal dimerization domain. In this study, we have determined the structures of the free KorA repressor and two complexes each bound to a 20-bp palindromic DNA duplex containing its consensus operator sequence. Using a combination of X-ray crystallography, nuclear magnetic resonance spectroscopy, SAXS and molecular dynamics calculations, we show that the linker between the two domains is very flexible and the protein remains highly mobile in the presence of DNA. This flexibility allows the DNA-binding domains of the dimer to straddle the operator DNA on binding and is likely to be important in cooperative binding to KorB. Unexpectedly, the C-terminal domain of KorA is structurally similar to the dimerization domain of the tumour suppressor p53.
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Affiliation(s)
- Karthik V Rajasekar
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Andrew L Lovering
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Felician Dancea
- School of Cancer Studies, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - David J Scott
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Nottingham LE12 5RD, UK
| | - Sarah A Harris
- School of Physics and Astronomy and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Lewis E H Bingle
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | - Christopher M Thomas
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Eva I Hyde
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Scott A White
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Rajasekar KV, Campbell LJ, Nietlispach D, Owen D, Mott HR. 1H, 13C and 15N resonance assignments of the GTPase-activating (GAP) and Ral binding domains (GBD) of RLIP76 (RalBP1). Biomol NMR Assign 2012; 6:119-122. [PMID: 21915608 DOI: 10.1007/s12104-011-9337-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/25/2011] [Indexed: 05/31/2023]
Abstract
RLIP76 (also known as RalBP1) is an effector for Ral small G proteins. RLIP76 is a multifunctional, multi-domain protein that includes a GTPase activating domain for the Rho family (RhoGAP domain) and a GTPase binding domain (GBD) for the Ral small G proteins. The juxtaposition of these two domains (GAP and GBD) may be a strategy employed to co-ordinate regulation of Rho family and Ral-controlled signalling pathways at a crossover node. Here we present the (1)H, (15)N and (13)C NMR backbone and sidechain resonance assignments of the GAP and GBD di-domain (31 kDa).
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Affiliation(s)
- Karthik V Rajasekar
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge CB2 1GA, UK
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Bingle LEH, Rajasekar KV, Muntaha ST, Nadella V, Hyde EI, Thomas CM. A single aromatic residue in transcriptional repressor protein KorA is critical for cooperativity with its co-regulator KorB. Mol Microbiol 2008; 70:1502-14. [PMID: 19019158 PMCID: PMC2680271 DOI: 10.1111/j.1365-2958.2008.06498.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A central feature of broad host range IncP-1 plasmids is the set of regulatory circuits that tightly control plasmid core functions under steady-state conditions. Cooperativity between KorB and either KorA or TrbA repressor proteins is a key element of these circuits and deletion analysis has implicated the conserved C-terminal domain of KorA and TrbA in this interaction. By NMR we show that KorA and KorB interact directly and identify KorA amino acids that are affected on KorB binding. Studies on mutants showed that tyrosine 84 (or phenylalanine, in some alleles) is dispensable for repressor activity but critical for the specific interaction with KorB in both in vivo reporter gene assays and in vitro electrophoretic mobility shift and co-purification assays. This confirms that direct and specific protein–protein interactions are responsible for the cooperativity observed between KorB and its corepressors and lays the basis for determining the biological importance of this cooperativity.
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Affiliation(s)
- Lewis E H Bingle
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Rajasekar KV, Bingle LEH, Thomas CM, Hyde EI. 1H, 13C and 15N assignments of the KorA global transcriptional repressor protein from the low copy number IncP-1 plasmid, RK2. J Biomol NMR 2006; 36 Suppl 1:71. [PMID: 16944275 DOI: 10.1007/s10858-006-9060-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Accepted: 07/03/2006] [Indexed: 05/11/2023]
Affiliation(s)
- K V Rajasekar
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK,
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