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Pipalović G, Filić Ž, Ćehić M, Paradžik T, Zahradka K, Crnolatac I, Vujaklija D. Impact of C-terminal domains of paralogous single-stranded DNA binding proteins from Streptomyces coelicolor on their biophysical properties and biological functions. Int J Biol Macromol 2024; 268:131544. [PMID: 38614173 DOI: 10.1016/j.ijbiomac.2024.131544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 04/15/2024]
Abstract
Single-stranded DNA-binding proteins (SSB) are crucial in DNA metabolism. While Escherichia coli SSB is extensively studied, the significance of its C-terminal domain has only recently emerged. This study explored the significance of C-domains of two paralogous Ssb proteins in S. coelicolor. Mutational analyses of C-domains uncovered a novel role of SsbA during sporulation-specific cell division and demonstrated that the C-tip is non-essential for survival. In vitro methods revealed altered biophysical and biochemical properties of Ssb proteins with modified C-domains. Determined hydrodynamic properties suggested that the C-domains of SsbA and SsbB occupy a globular position proposed to mediate cooperative binding. Only SsbA was found to form biomolecular condensates independent of the C-tip. Interestingly, the truncated C-domain of SsbA increased the molar enthalpy of unfolding. Additionally, calorimetric titrations revealed that C-domain mutations affected ssDNA binding. Moreover, this analysis showed that the SsbA C-tip aids binding most likely by regulating the position of the flexible C-domain. It also highlighted ssDNA-induced conformational mobility restrictions of all Ssb variants. Finally, the gel mobility shift assay confirmed that the intrinsically disordered linker is essential for cooperative binding of SsbA. These findings highlight the important role of the C-domain in the functioning of SsbA and SsbB proteins.
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Affiliation(s)
- Goran Pipalović
- Division of Physical Chemistry, Institute Ruđer Bošković, Zagreb, Croatia
| | - Želimira Filić
- Division of Physical Chemistry, Institute Ruđer Bošković, Zagreb, Croatia
| | - Mirsada Ćehić
- Division of Physical Chemistry, Institute Ruđer Bošković, Zagreb, Croatia
| | - Tina Paradžik
- Division of Physical Chemistry, Institute Ruđer Bošković, Zagreb, Croatia
| | - Ksenija Zahradka
- Division of Molecular Biology, Institute Ruđer Bošković, Zagreb, Croatia
| | - Ivo Crnolatac
- Division of Organic Chemistry and Biochemistry, Institute Ruđer Bošković, Zagreb, Croatia.
| | - Dušica Vujaklija
- Division of Physical Chemistry, Institute Ruđer Bošković, Zagreb, Croatia.
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2
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Lee CY, Chen YC, Huang YH, Lien Y, Huang CY. Cytotoxicity and Multi-Enzyme Inhibition of Nepenthes miranda Stem Extract on H838 Human Non-Small Cell Lung Cancer Cells and RPA32, Elastase, Tyrosinase, and Hyaluronidase Proteins. PLANTS (BASEL, SWITZERLAND) 2024; 13:797. [PMID: 38592804 PMCID: PMC10974603 DOI: 10.3390/plants13060797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 04/11/2024]
Abstract
The carnivorous pitcher plants of the genus Nepenthes have long been known for their ethnobotanical applications. In this study, we prepared various extracts from the pitcher, stem, and leaf of Nepenthes miranda using 100% ethanol and assessed their inhibitory effects on key enzymes related to skin aging, including elastase, tyrosinase, and hyaluronidase. The cytotoxicity of the stem extract of N. miranda on H838 human lung carcinoma cells were also characterized by effects on cell survival, migration, proliferation, apoptosis induction, and DNA damage. The cytotoxic efficacy of the extract was enhanced when combined with the chemotherapeutic agent 5-fluorouracil (5-FU), indicating a synergistic effect. Flow cytometry analysis suggested that the stem extract might suppress H838 cell proliferation by inducing G2 cell cycle arrest, thereby inhibiting carcinoma cell proliferation. Gas chromatography-mass spectrometry (GC-MS) enabled the tentative identification of the 15 most abundant compounds in the stem extract of N. miranda. Notably, the extract showed a potent inhibition of the human RPA32 protein (huRPA32), critical for DNA replication, suggesting a novel mechanism for its anticancer action. Molecular docking studies further substantiated the interaction between the extract and huRPA32, highlighting bioactive compounds, especially the two most abundant constituents, stigmast-5-en-3-ol and plumbagin, as potential inhibitors of huRPA32's DNA-binding activity, offering promising avenues for cancer therapy. Overall, our findings position the stem extract of N. miranda as a promising source of natural compounds for anticancer therapeutics and anti-skin-aging treatments, warranting further investigation into its molecular mechanisms and potential clinical applications.
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Affiliation(s)
- Ching-Yi Lee
- Department of Internal Medicine, Tao Yuan General Hospital, Ministry of Health and Welfare, Taoyuan 330, Taiwan
| | - Yu-Cheng Chen
- Department of Internal Medicine, Tao Yuan General Hospital, Ministry of Health and Welfare, Taoyuan 330, Taiwan
| | - Yen-Hua Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Yi Lien
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung City 402, Taiwan
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3
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Schuurs ZP, Martyn AP, Soltau CP, Beard S, Shah ET, Adams MN, Croft LV, O’Byrne KJ, Richard DJ, Gandhi NS. An Exploration of Small Molecules That Bind Human Single-Stranded DNA Binding Protein 1. BIOLOGY 2023; 12:1405. [PMID: 37998004 PMCID: PMC10669474 DOI: 10.3390/biology12111405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/24/2023] [Accepted: 10/30/2023] [Indexed: 11/25/2023]
Abstract
Human single-stranded DNA binding protein 1 (hSSB1) is critical to preserving genome stability, interacting with single-stranded DNA (ssDNA) through an oligonucleotide/oligosaccharide binding-fold. The depletion of hSSB1 in cell-line models leads to aberrant DNA repair and increased sensitivity to irradiation. hSSB1 is over-expressed in several types of cancers, suggesting that hSSB1 could be a novel therapeutic target in malignant disease. hSSB1 binding studies have focused on DNA; however, despite the availability of 3D structures, small molecules targeting hSSB1 have not been explored. Quinoline derivatives targeting hSSB1 were designed through a virtual fragment-based screening process, synthesizing them using AlphaLISA and EMSA to determine their affinity for hSSB1. In parallel, we further screened a structurally diverse compound library against hSSB1 using the same biochemical assays. Three compounds with nanomolar affinity for hSSB1 were identified, exhibiting cytotoxicity in an osteosarcoma cell line. To our knowledge, this is the first study to identify small molecules that modulate hSSB1 activity. Molecular dynamics simulations indicated that three of the compounds that were tested bound to the ssDNA-binding site of hSSB1, providing a framework for the further elucidation of inhibition mechanisms. These data suggest that small molecules can disrupt the interaction between hSSB1 and ssDNA, and may also affect the ability of cells to repair DNA damage. This test study of small molecules holds the potential to provide insights into fundamental biochemical questions regarding the OB-fold.
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Affiliation(s)
- Zachariah P. Schuurs
- Centre for Genomics and Personalised Health, School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia; (Z.P.S.); (A.P.M.)
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
| | - Alexander P. Martyn
- Centre for Genomics and Personalised Health, School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia; (Z.P.S.); (A.P.M.)
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
| | - Carl P. Soltau
- School of Chemistry and Physics, Centre for Materials Science, Queensland University of Technology, Brisbane, QLD 4000, Australia;
| | - Sam Beard
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
| | - Esha T. Shah
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Translational Research Institute, Woolloongabba, QLD 4102, Australia
| | - Mark N. Adams
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Translational Research Institute, Woolloongabba, QLD 4102, Australia
| | - Laura V. Croft
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Translational Research Institute, Woolloongabba, QLD 4102, Australia
| | - Kenneth J. O’Byrne
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- Cancer Services, Princess Alexandra Hospital—Metro South Health, Woolloongabba, QLD 4102, Australia
| | - Derek J. Richard
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Translational Research Institute, Woolloongabba, QLD 4102, Australia
| | - Neha S. Gandhi
- Centre for Genomics and Personalised Health, School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia; (Z.P.S.); (A.P.M.)
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, Queensland University of Technology (QUT), Translational Research Institute (TRI), Woolloongabba, QLD 4102, Australia; (S.B.); (M.N.A.); (L.V.C.); (K.J.O.); (D.J.R.)
- Department of Computer Science and Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576104, India
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Su HH, Huang YH, Lien Y, Yang PC, Huang CY. Crystal Structure of DNA Replication Protein SsbA Complexed with the Anticancer Drug 5-Fluorouracil. Int J Mol Sci 2023; 24:14899. [PMID: 37834349 PMCID: PMC10573954 DOI: 10.3390/ijms241914899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 10/15/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play a crucial role in DNA metabolism by binding and stabilizing single-stranded DNA (ssDNA) intermediates. Through their multifaceted roles in DNA replication, recombination, repair, replication restart, and other cellular processes, SSB emerges as a central player in maintaining genomic integrity. These attributes collectively position SSBs as essential guardians of genomic integrity, establishing interactions with an array of distinct proteins. Unlike Escherichia coli, which contains only one type of SSB, some bacteria have two paralogous SSBs, referred to as SsbA and SsbB. In this study, we identified Staphylococcus aureus SsbA (SaSsbA) as a fresh addition to the roster of the anticancer drug 5-fluorouracil (5-FU) binding proteins, thereby expanding the ambit of the 5-FU interactome to encompass this DNA replication protein. To investigate the binding mode, we solved the complexed crystal structure with 5-FU at 2.3 Å (PDB ID 7YM1). The structure of glycerol-bound SaSsbA was also determined at 1.8 Å (PDB ID 8GW5). The interaction between 5-FU and SaSsbA was found to involve R18, P21, V52, F54, Q78, R80, E94, and V96. Based on the collective results from mutational and structural analyses, it became evident that SaSsbA's mode of binding with 5-FU diverges from that of SaSsbB. This complexed structure also holds the potential to furnish valuable comprehension regarding how 5-FU might bind to and impede analogous proteins in humans, particularly within cancer-related signaling pathways. Leveraging the information furnished by the glycerol and 5-FU binding sites, the complexed structures of SaSsbA bring to the forefront the potential viability of several interactive residues as potential targets for therapeutic interventions aimed at curtailing SaSsbA activity. Acknowledging the capacity of microbiota to influence the host's response to 5-FU, there emerges a pressing need for further research to revisit the roles that bacterial and human SSBs play in the realm of anticancer therapy.
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Affiliation(s)
- Hsin-Hui Su
- Department of Pharmacy, Chia Nan University of Pharmacy and Science, Tainan City 717, Taiwan
| | - Yen-Hua Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Yi Lien
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Po-Chun Yang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung City 402, Taiwan
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5
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Mukherjee A, Hossain Z, Erben E, Ma S, Choi JY, Kim HS. Identification of a small-molecule inhibitor that selectively blocks DNA-binding by Trypanosoma brucei replication protein A1. Nat Commun 2023; 14:4390. [PMID: 37474515 PMCID: PMC10359466 DOI: 10.1038/s41467-023-39839-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 06/30/2023] [Indexed: 07/22/2023] Open
Abstract
Replication Protein A (RPA) is a broadly conserved complex comprised of the RPA1, 2 and 3 subunits. RPA protects the exposed single-stranded DNA (ssDNA) during DNA replication and repair. Using structural modeling, we discover an inhibitor, JC-229, that targets RPA1 in Trypanosoma brucei, the causative parasite of African trypanosomiasis. The inhibitor is highly toxic to T. brucei cells, while mildly toxic to human cells. JC-229 treatment mimics the effects of TbRPA1 depletion, including DNA replication inhibition and DNA damage accumulation. In-vitro ssDNA-binding assays demonstrate that JC-229 inhibits the activity of TbRPA1, but not the human ortholog. Indeed, despite the high sequence identity with T. cruzi and Leishmania RPA1, JC-229 only impacts the ssDNA-binding activity of TbRPA1. Site-directed mutagenesis confirms that the DNA-Binding Domain A (DBD-A) in TbRPA1 contains a JC-229 binding pocket. Residue Serine 105 determines specific binding and inhibition of TbRPA1 but not T. cruzi and Leishmania RPA1. Our data suggest a path toward developing and testing highly specific inhibitors for the treatment of African trypanosomiasis.
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Affiliation(s)
- Aditi Mukherjee
- Public Health Research Institute, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA
| | - Zakir Hossain
- Department of Chemistry and Biochemistry, Queens College, New York, NY, 11367, USA
| | - Esteban Erben
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Provincia de Buenos Aires, Argentina
- Escuela de Bio y Nanotecnologías (EByN), Universidad Nacional de San Martín, San Martín, Provincia de Buenos Aires, Argentina
| | - Shuai Ma
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Jun Yong Choi
- Department of Chemistry and Biochemistry, Queens College, New York, NY, 11367, USA.
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
| | - Hee-Sook Kim
- Public Health Research Institute, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA.
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers Biomedical Health Sciences, Newark, NJ, 07103, USA.
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Lin ES, Huang YH, Chung JC, Su HH, Huang CY. The Inhibitory Effects and Cytotoxic Activities of the Stem Extract of Nepenthes miranda against Single-Stranded DNA-Binding Protein and Oral Carcinoma Cells. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12112188. [PMID: 37299167 DOI: 10.3390/plants12112188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
The carnivorous pitcher plants of the genus Nepenthes exhibit many ethnobotanical uses, including treatments of stomachache and fever. In this study, we prepared different extracts from the pitcher, stem, and leaf extracts of Nepenthes miranda obtained using 100% methanol and analyzed their inhibitory effects on recombinant single-stranded DNA-binding protein (SSB) from Klebsiella pneumoniae (KpSSB). SSB is essential for DNA replication and cell survival and thus an attractive target for potential antipathogen chemotherapy. Different extracts prepared from Sinningia bullata, a tuberous member of the flowering plant family Gesneriaceae, were also used to investigate anti-KpSSB properties. Among these extracts, the stem extract of N. miranda exhibited the highest anti-KpSSB activity with an IC50 value of 15.0 ± 1.8 μg/mL. The cytotoxic effects of the stem extract of N. miranda on the survival and apoptosis of the cancer cell lines Ca9-22 gingival carcinoma, CAL27 oral adenosquamous carcinoma, PC-9 pulmonary adenocarcinoma, B16F10 melanoma, and 4T1 mammary carcinoma cells were also demonstrated and compared. Based on collective data, the cytotoxic activities of the stem extract at a concentration of 20 μg/mL followed the order Ca9-22 > CAL27 > PC9 > 4T1 > B16F10 cells. The stem extract of N. miranda at a concentration of 40 μg/mL completely inhibited Ca9-22 cell migration and proliferation. In addition, incubation with this extract at a concentration of 20 μg/mL boosted the distribution of the G2 phase from 7.9% to 29.2% in the Ca9-22 cells; in other words, the stem extract might suppress Ca9-22 cell proliferation by inducing G2 cell cycle arrest. Through gas chromatography-mass spectrometry, the 16 most abundant compounds in the stem extract of N. miranda were tentatively identified. The 10 most abundant compounds in the stem extract of N. miranda were used for docking analysis, and their docking scores were compared. The binding capacity of these compounds was in the order sitosterol > hexadecanoic acid > oleic acid > plumbagin > 2-ethyl-3-methylnaphtho[2,3-b]thiophene-4,9-dione > methyl α-d-galactopyranoside > 3-methoxycatechol > catechol > pyrogallol > hydroxyhydroquinone; thus, sitosterol might exhibit the greatest inhibitory capacity against KpSSB among the selected compounds. Overall, these results may indicate the pharmacological potential of N. miranda for further therapeutic applications.
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Affiliation(s)
- En-Shyh Lin
- Department of Beauty Science, National Taichung University of Science and Technology, Taichung City 403, Taiwan
| | - Yen-Hua Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Jo-Chi Chung
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Hsin-Hui Su
- Department of Pharmacy, Chia Nan University of Pharmacy and Science, Tainan City 717, Taiwan
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung City 402, Taiwan
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Liu HW, Chiang WY, Huang YH, Huang CY. The Inhibitory Effects and Cytotoxic Activities of the Stem Extract of Sarracenia purpurea against Melanoma Cells and the SsbA Protein. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11223164. [PMID: 36432892 PMCID: PMC9692666 DOI: 10.3390/plants11223164] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 06/12/2023]
Abstract
The Staphylococcus aureus SsbA protein (SaSsbA) is a single-stranded DNA-binding protein (SSB) that is categorically required for DNA replication and cell survival, and it is thus an attractive target for potential antipathogen chemotherapy. In this study, we prepared the stem extract of Sarracenia purpurea obtained from 100% acetone to investigate its inhibitory effect against SaSsbA. In addition, the cytotoxic effects of this extract on the survival, apoptosis, proliferation, and migration of B16F10 melanoma cells were also examined. Initially, myricetin, quercetin, kaempferol, dihydroquercetin, dihydrokaempferol, rutin, catechin, β-amyrin, oridonin, thioflavin T, primuline, and thioflavin S were used as possible inhibitors against SaSsbA. Of these compounds, dihydrokaempferol and oridonin were capable of inhibiting the ssDNA-binding activity of SaSsbA with respective IC50 values of 750 ± 62 and 2607 ± 242 μM. Given the poor inhibition abilities of dihydrokaempferol and oridonin, we screened the extracts of S. purpurea, Nepenthes miranda, and Plinia cauliflora for SaSsbA inhibitors. The stem extract of S. purpurea exhibited high anti-SaSsbA activity, with an IC50 value of 4.0 ± 0.3 μg/mL. The most abundant compounds in the stem extract of S. purpurea were identified using gas chromatography−mass spectrometry. The top five most abundant contents in this extract were driman-8,11-diol, deoxysericealactone, stigmast-5-en-3-ol, apocynin, and α-amyrin. Using the MOE-Dock tool, the binding modes of these compounds, as well as dihydrokaempferol and oridonin, to SaSsbA were elucidated, and their binding energies were also calculated. Based on the S scores, the binding capacity of these compounds was in the following order: deoxysericealactone > dihydrokaempferol > apocynin > driman-8,11-diol > stigmast-5-en-3-ol > oridonin > α-amyrin. Incubation of B16F10 cells with the stem extract of S. purpurea at a concentration of 100 μg/mL caused deaths at the rate of 76%, reduced migration by 95%, suppressed proliferation and colony formation by 99%, and induced apoptosis, which was observed in 96% of the B16F10 cells. Overall, the collective data in this study indicate the pharmacological potential of the stem extract of S. purpurea for further medical applications.
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Affiliation(s)
- Hong-Wen Liu
- Department of Rheumatology and Immunology, Antai Medical Care Corporation Antai Tian-Sheng Memorial Hospital, Pingtung 928, Taiwan
| | - Wei-Yu Chiang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Yen-Hua Huang
- Department of Rheumatology and Immunology, Antai Medical Care Corporation Antai Tian-Sheng Memorial Hospital, Pingtung 928, Taiwan
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung City 402, Taiwan
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Lin ES, Huang YH, Luo RH, Basharat Z, Huang CY. Crystal Structure of an SSB Protein from Salmonella enterica and Its Inhibition by Flavanonol Taxifolin. Int J Mol Sci 2022; 23:ijms23084399. [PMID: 35457218 PMCID: PMC9029707 DOI: 10.3390/ijms23084399] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/12/2022] [Accepted: 04/14/2022] [Indexed: 12/13/2022] Open
Abstract
Single-stranded DNA (ssDNA)-binding proteins (SSBs) play a central role in cells by participating in DNA metabolism, including replication, repair, recombination, and replication fork restart. SSBs are essential for cell survival and thus an attractive target for potential anti-pathogen chemotherapy. In this study, we determined the crystal structure and examined the size of the ssDNA-binding site of an SSB from Salmonella enterica serovar Typhimurium LT2 (SeSSB), a ubiquitous opportunistic pathogen which is highly resistant to antibiotics. The crystal structure was solved at a resolution of 2.8 Å (PDB ID 7F25), indicating that the SeSSB monomer possesses an oligonucleotide/oligosaccharide-binding (OB) fold domain at its N-terminus and a flexible tail at its C-terminus. The core of the OB-fold in the SeSSB is made of a six-stranded β-barrel capped by an α-helix. The crystal structure of the SeSSB contained two monomers per asymmetric unit, which may indicate the formation of a dimer. However, the gel-filtration chromatography analysis showed that the SeSSB forms a tetramer in solution. Through an electrophoretic mobility shift analysis, we characterized the stoichiometry of the SeSSB complexed with a series of ssDNA dA homopolymers, and the size of the ssDNA-binding site was determined to be around 22 nt. We also found the flavanonol taxifolin, also known as dihydroquercetin, capable of inhibiting the ssDNA-binding activity of the SeSSB. Thus, this result extended the SSB interactome to include taxifolin, a natural product with a wide range of promising pharmacological activities.
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Affiliation(s)
- En-Shyh Lin
- Department of Beauty Science, National Taichung University of Science and Technology, No. 193, Sec.1, San min Rd., Taichung City 403, Taiwan;
| | - Yen-Hua Huang
- Department of Biomedical Sciences, Chung Shan Medical University, No. 110, Sec.1, Chien-Kuo N. Rd., Taichung City 402, Taiwan; (Y.-H.H.); (R.-H.L.)
| | - Ren-Hong Luo
- Department of Biomedical Sciences, Chung Shan Medical University, No. 110, Sec.1, Chien-Kuo N. Rd., Taichung City 402, Taiwan; (Y.-H.H.); (R.-H.L.)
| | - Zarrin Basharat
- Jamil–ur–Rahman Center for Genome Research, Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan;
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, No. 110, Sec.1, Chien-Kuo N. Rd., Taichung City 402, Taiwan; (Y.-H.H.); (R.-H.L.)
- Department of Medical Research, Chung Shan Medical University Hospital, No. 110, Sec.1, Chien-Kuo N. Rd., Taichung City 402, Taiwan
- Correspondence:
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Abstract
The majority of drug discovery efforts against herpesviruses have focused on nucleoside analogs that target viral DNA polymerases, agents that are associated with dose-limiting toxicity and/or a narrow spectrum of activity. We are pursuing a strategy based on targeting two-metal ion-dependent (TMID) viral enzymes. This family of enzymes consists of structurally related proteins that share common active sites containing conserved carboxylates predicted to coordinate divalent cations essential for catalysis. Compounds that target TMID enzymes, such as HIV integrase and influenza endoribonuclease, have been successfully developed for clinical use. HIV integrase inhibitors have been reported to inhibit replication of herpes simplex virus (HSV) and other herpesviruses; however, the molecular targets of their antiviral activities have not been identified. We employed a candidate-based approach utilizing several two-metal-directed chemotypes and the potential viral TMID enzymatic targets in an effort to correlate target-based activity with antiviral potency. The panel of compounds tested included integrase inhibitors, the anti-influenza agent baloxavir, three natural products previously shown to exhibit anti-HSV activity, and two 8-hydroxyquinolines (8-HQs), AK-157 and AK-166, from our in-house program. The integrase inhibitors exhibited weak overall anti-HSV-1 activity, while the 8-HQs were shown to inhibit both HSV-1 and cytomegalovirus (CMV). Target-based analysis demonstrated that none of the antiviral compounds acted by inhibiting ICP8, contradicting previous reports. On the other hand, baloxavir inhibited the proofreading exonuclease of HSV polymerase, while AK-157 and AK-166 inhibited the alkaline exonuclease UL12. In addition, AK-157 also inhibited the catalytic activity of the HSV polymerase, which provides an opportunity to potentially develop dual-targeting agents against herpesviruses. IMPORTANCE Human herpesviruses (HHVs) establish lifelong latent infections, which undergo periodic reactivation and remain a major cause of morbidity and mortality, especially in immunocompromised individuals. Currently, HHV infections are treated primarily with agents that target viral DNA polymerase, including nucleoside analogs; however, long-term treatment can be complicated by the development of drug resistance. New therapies with novel modes of action would be important not only for the treatment of resistant viruses but also for use in combination therapy to reduce dose-limiting toxicities and potentially eliminate infection. Since many essential HHV proteins are well conserved, inhibitors of novel targets would ideally exhibit broad-spectrum activity against multiple HHVs.
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10
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Littler DR, Mohanty B, Lowery SA, Colson RN, Gully BS, Perlman S, Scanlon MJ, Rossjohn J. Binding of a pyrimidine RNA base-mimic to SARS-CoV-2 nonstructural protein 9. J Biol Chem 2021; 297:101018. [PMID: 34331944 PMCID: PMC8317483 DOI: 10.1016/j.jbc.2021.101018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/21/2021] [Accepted: 07/27/2021] [Indexed: 01/18/2023] Open
Abstract
The coronaviral nonstructural protein 9 (Nsp9) is essential for viral replication; it is the primary substrate of Nsp12's pseudokinase domain within the viral replication transcription complex, an association that also recruits other components during different stages of RNA reproduction. In the unmodified state, Nsp9 forms an obligate homodimer via an essential GxxxG protein-interaction motif, but its ssRNA-binding mechanism remains unknown. Using structural biological techniques, here we show that a base-mimicking compound identified from a small molecule fragment screen engages Nsp9 via a tetrameric Pi-Pi stacking interaction that induces the formation of a parallel trimer-of-dimers. This oligomerization mechanism allows an interchange of "latching" N-termini, the charges of which contribute to a series of electropositive channels that suggests a potential interface for viral RNA. The identified pyrrolo-pyrimidine compound may also serve as a potential starting point for the development of compounds seeking to probe Nsp9's role within SARS-CoV-2 replication.
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Affiliation(s)
- Dene R Littler
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Sydney Analytical Core Research Facility, The University of Sydney, Sydney, New South Wales, Australia; ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Shea A Lowery
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Rhys N Colson
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Benjamin S Gully
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Stanley Perlman
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
| | - Jamie Rossjohn
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Institute of Infection and Immunity, Cardiff University School of Medicine, Cardiff, United Kingdom.
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11
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Capochiani de Iudicibus R, Tomek P, Palmer BD, Tijono SM, Flanagan JU, Ching LM. Parallel discovery of selective and dual inhibitors of tryptophan dioxygenases IDO1 and TDO2 with a newly-modified enzymatic assay. Bioorg Med Chem 2021; 39:116160. [PMID: 33901770 DOI: 10.1016/j.bmc.2021.116160] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 11/18/2022]
Abstract
The expression of tryptophan catabolising enzyme indoleamine 2,3-dioxygenase 1 (IDO1) or tryptophan 2,3-dioxygenase 2 (TDO2) in cancers is associated with suppressed immunity and poor patient prognosis. Results from human clinical trials of IDO1 inhibitors have been disappointing. There is now a strong interest in the development of TDO2-selective or dual IDO1/TDO2 inhibitors that may surpass IDO1 inhibitors by providing broader efficacy and blocking constitutively-expressed hepatic TDO2. To expedite the discovery of novel TDO2-specific and dual inhibitors, an assay that enabled the efficient and accurate measurement of the inhibitory activity of compounds against both IDO1 and TDO2 enzymes, concurrently in the same experiment was established to screen 5,682 compounds that included the National Cancer Institute Diversity set 5, for inhibition of IDO1 and TDO2 activity. This screen identified 82 compounds that inhibited either IDO1, TDO2 or both enzymes > 50% at 20 µM. Thirty Pan Assay Interference compounds were removed from the list and the IC50 of the remaining 52 compounds against IDO1 and TDO2 was subsequently determined using the newly-developed concurrent assay. Ten compounds were confirmed as dual IDO1/TDO2 inhibitors having IC50 values under 50 µM against both enzymes and within 2-fold of each other. Six compounds with IC50 values between 1.39 and 8.41 µM were identified as potential TDO2-selective leads. The use of this concurrent protocol is anticipated to expedite the discovery of novel leads for dual and selective inhibitors against IDO1 and or TDO2 and speed the evaluation of novel analogues that will ensue.
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Affiliation(s)
- Rossella Capochiani de Iudicibus
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Petr Tomek
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Brian D Palmer
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Sofian M Tijono
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Jack U Flanagan
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | - Lai-Ming Ching
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, The University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
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12
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Lin ES, Huang CY. Crystal structure of the single-stranded DNA-binding protein SsbB in complex with the anticancer drug 5-fluorouracil: Extension of the 5-fluorouracil interactome to include the oligonucleotide/oligosaccharide-binding fold protein. Biochem Biophys Res Commun 2020; 534:41-46. [PMID: 33310186 DOI: 10.1016/j.bbrc.2020.11.125] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 11/28/2020] [Accepted: 11/30/2020] [Indexed: 12/30/2022]
Abstract
Single-stranded DNA-binding proteins (SSBs) are essential to cells because they participate in DNA metabolic processes, such as DNA replication, repair, and recombination. Some bacteria possess more than one paralogous SSB. Three similar SSBs, namely, SsbA, SsbB, and SsbC, are found in Staphylococcus aureus. Whether the FDA-approved clinical drug 5-fluorouracil (5-FU) that is used to target the enzyme thymidylate synthase for anticancer therapy can also bind to SSBs remains unknown. In this study, we found that 5-FU could form a stable complex with S. aureus SsbB (SaSsbB). We cocrystallized 5-FU with SaSsbB and solved complex structures to assess binding modes. Two complex forms of the structures were determined, namely, the individual asymmetric unit (two SaSsbB monomers) containing one (PDB entry 7D8J) or two 5-FU molecules (PDB entry 7DEP). The locations of 5-FU in these two SaSsbB complexes were similar regardless of the binding ratio. The structures revealed that residues T12, K13, T30, F48, and N50 of SaSsbB were involved in 5-FU binding. The mutations of T12, K13, and F48 caused the low 5-FU binding activity of SaSsbB, a result consistent with the structural analysis results. Taken together, the complexed structure and the binding mode analysis of SaSsbB extended the anticancer drug 5-FU interactome to include the oligonucleotide/oligosaccharide-binding fold protein.
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Affiliation(s)
- En-Shyh Lin
- Department of Beauty Science, National Taichung University of Science and Technology, No.193 Sec.1 San-Min Rd., Taichung City, Taiwan
| | - Cheng-Yang Huang
- School of Biomedical Sciences, Chung Shan Medical University, No.110 Sec.1 Chien-Kuo N. Rd., Taichung City, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, No.110 Sec.1 Chien-Kuo N. Rd., Taichung City, Taiwan.
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13
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Swain A, Gnanasekar P, Prava J, Rajeev AC, Kesarwani P, Lahiri C, Pan A. A Comparative Genomics Approach for Shortlisting Broad-Spectrum Drug Targets in Nontuberculous Mycobacteria. Microb Drug Resist 2020; 27:212-226. [PMID: 32936741 DOI: 10.1089/mdr.2020.0161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Many members of nontuberculous mycobacteria (NTM) are opportunistic pathogens causing several infections in animals. The incidence of NTM infections and emergence of drug-resistant NTM strains are rising worldwide, emphasizing the need to develop novel anti-NTM drugs. The present study is aimed to identify broad-spectrum drug targets in NTM using a comparative genomics approach. The study identified 537 core proteins in NTM of which 45 were pathogen specific and essential for the survival of pathogens. Furthermore, druggability analysis indicated that 15 were druggable among those 45 proteins. These 15 proteins, which were core proteins, pathogen-specific, essential, and druggable, were considered as potential broad-spectrum candidates. Based on their locations in cytoplasm and membrane, targets were classified as drug and vaccine targets. The identified 15 targets were different enzymes, carrier proteins, transcriptional regulator, two-component system protein, ribosomal, and binding proteins. The identified targets could further be utilized by researchers to design inhibitors for the discovery of antimicrobial agents.
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Affiliation(s)
- Aishwarya Swain
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | | | - Jyoti Prava
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Athira C Rajeev
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Pragya Kesarwani
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Chandrajit Lahiri
- Department of Biological Sciences, Sunway University, Petaling Jaya, Malaysia
| | - Archana Pan
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
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14
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Boutard N, Sabiniarz A, Czerwińska K, Jarosz M, Cierpich A, Kolasińska E, Wiklik K, Gluza K, Commandeur C, Buda A, Stasiowska A, Bobowska A, Galek M, Fabritius CH, Bugaj M, Palacz E, Mazan A, Zarębski A, Krawczyńska K, Żurawska M, Zawadzki P, Milik M, Węgrzyn P, Dobrzańska M, Brzózka K, Kowalczyk P. 5-Keto-3-cyano-2,4-diaminothiophenes as selective maternal embryonic leucine zipper kinase inhibitors. Bioorg Med Chem Lett 2018; 29:607-613. [PMID: 30626559 DOI: 10.1016/j.bmcl.2018.12.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/17/2018] [Accepted: 12/21/2018] [Indexed: 01/06/2023]
Abstract
Maternal embryonic leucine zipper kinase (MELK) is involved in several key cellular processes and displays increased levels of expression in numerous cancer classes (colon, breast, brain, ovary, prostate and lung). Although no selective MELK inhibitors have yet been approved, increasing evidence suggest that inhibition of MELK would constitute a promising approach for cancer therapy. A weak high-throughput screening hit (17, IC50 ≈ 5 μM) with lead-like properties was optimized for MELK inhibition. The early identification of a plausible binding mode by molecular modeling offered guidance in the choice of modifications towards compound 52 which displayed a 98 nM IC50. A good selectivity profile was achieved for a representative member of the series (29) in a 486 protein kinase panel. Future elaboration of 52 has the potential to deliver compounds for further development with chemotherapeutic aims.
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Affiliation(s)
| | | | | | | | - Anna Cierpich
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | | | | | | | | | - Anna Buda
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | | | | | - Mariusz Galek
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | | | - Marta Bugaj
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | - Edyta Palacz
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | - Andrzej Mazan
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
| | | | | | | | | | - Mariusz Milik
- Selvita S.A, Bobrzyńskiego, 14, 30-338 Kraków, Poland
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15
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Huang CY. Crystal structure of SSB complexed with inhibitor myricetin. Biochem Biophys Res Commun 2018; 504:704-708. [DOI: 10.1016/j.bbrc.2018.08.188] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022]
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16
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Huang YH, Huang CY. SAAV2152 is a single-stranded DNA binding protein: the third SSB in Staphylococcus aureus. Oncotarget 2018; 9:20239-20254. [PMID: 29755648 PMCID: PMC5945547 DOI: 10.18632/oncotarget.24427] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 01/31/2018] [Indexed: 11/25/2022] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play crucial roles in DNA replication, repair, and recombination. Unlike E. coli, which contains only one type of SSB (EcSSB), some bacteria have two paralogous SSBs, namely, SsbA and SsbB. In this study, we found the third SSB-like protein in Staphylococcus aureus, SAAV2152, which was designated as SaSsbC. SaSsbC is a protein of 131 amino acids and shares 38%, 36%, and 33% sequence identity to SaSsbB, SaSsbA, and EcSSB, respectively. Gene map analysis showed that unlike the E. coli ssb gene, which is adjacent to uvrA gene, the S. aureus ssb gene SAAV2152 is flanked by the putative SceD, the putative YwpF, and fabZ genes. A homology model showed that SaSsbC consists of the classic oligonucleotide/oligosaccharide-binding fold at the N-terminus. At the C-terminus, SaSsbC did not exhibit sequence similarity to that of EcSSB. Electrophoretic mobility shift analysis showed that SaSsbC formed a single complex with ssDNA of different lengths. Mutational analysis revealed that Tyr36, Tyr47, Phe53, and Tyr81 in SaSsbC are at positions that structurally correspond to the important residues of EcSSB for binding to ssDNA and are also critical for SaSsbC to bind ssDNA. Unlike EcSSB, which can stimulate EcPriA, SaSsbC did not affect the activity of SaPriA. In addition, SaSsbA inhibitor 9-methyl-2,3,7-trihydroxy-6-fluorone (NSC5426) could inhibit the ssDNA-binding activity of SaSsbC with IC50 of 78 μM. In conclusion, this study has identified and characterized SAAV2152 as a kind of SSB, and further research can directly focus on determining its actual physiological role in S. aureus.
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Affiliation(s)
- Yen-Hua Huang
- School of Biomedical Sciences, Chung Shan Medical University, Taichung City, Taiwan
| | - Cheng-Yang Huang
- School of Biomedical Sciences, Chung Shan Medical University, Taichung City, Taiwan.,Department of Medical Research, Chung Shan Medical University Hospital, Taichung City, Taiwan
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17
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Chen KL, Cheng JH, Lin CY, Huang YH, Huang CY. Characterization of single-stranded DNA-binding protein SsbB fromStaphylococcus aureus: SsbB cannot stimulate PriA helicase. RSC Adv 2018; 8:28367-28375. [PMID: 35542479 PMCID: PMC9084298 DOI: 10.1039/c8ra04392b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/28/2018] [Indexed: 11/21/2022] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) are essential to cells as they participate in DNA metabolic processes, such as DNA replication, repair, and recombination. The functions of SSBs have been studied extensively in Escherichia coli. Unlike E. coli, which contains only one type of SSB (EcSSB), some bacteria have more than one paralogous SSB. In Staphylococcus aureus, three SSBs are found, namely, SsbA, SaSsbB, and SsbC. While EcSSB can significantly stimulate EcPriA helicase, SaSsbA does not affect the SaPriA activity. It remains unclear whether SsbBs can participate in the PriA-directed DNA replication restart process. In this study, we characterized the properties of SaSsbBs through structural and functional analyses. Crystal structure of SaSsbB determined at 2.9 Å resolution (PDB entry 5YYU) revealed four OB folds in the N-terminal DNA-binding domain. DNA binding analysis using EMSA showed that SaSsbB binds to ssDNA with greater affinity than SaSsbA does. Gene map analysis demonstrated that SAAV0835 encoding SaSsbB is flanked by unknown genes encoding hypothetical proteins, namely, putative Sipho_Gp157, ERF, and HNHc_6 gene products. Structure-based mutational analysis indicated that the four aromatic residues (Phe37, Phe48, Phe54, and Tyr82) in SaSsbB are at positions that structurally correspond to the important residues of EcSSB for binding to ssDNA and are also critical for SaSsbB to bind ssDNA. Similar to EcSSB and other SSBs such as SaSsbA and SaSsbC, SaSsbB also exhibited high thermostability. However, unlike EcSSB, which can stimulate EcPriA, SaSsbB did not affect the activity of SaPriA. Based on results in this study and previous works, we therefore established that SsbA and SsbB, as well as SsbC, do not stimulate PriA activity. Single-stranded DNA-binding proteins (SSBs) are essential to cells as they participate in DNA metabolic processes, such as DNA replication, repair, and recombination.![]()
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Affiliation(s)
- Kuan-Lin Chen
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
| | - Jen-Hao Cheng
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
| | - Chih-Yang Lin
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
- School of Medicine
| | - Yen-Hua Huang
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
| | - Cheng-Yang Huang
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
- Department of Medical Research
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18
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Huang YH, Huang CY. The glycine-rich flexible region in SSB is crucial for PriA stimulation. RSC Adv 2018; 8:35280-35288. [PMID: 35547063 PMCID: PMC9087215 DOI: 10.1039/c8ra07306f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/09/2018] [Indexed: 11/21/2022] Open
Abstract
Single-stranded DNA-binding protein (SSB) is essential for all DNA-dependent cellular processes. The mechanism through which PriA helicase, an initiator protein in the DNA replication restart process, is stimulated by SSB in Escherichia coli (Ec) has been established. Nevertheless, whether or not PriA stimulated by SSB is conserved among Gram-negative bacteria remains unclear, and the SSB specificity for the stimulation effect on PriA is unknown. In this study, three similar SSBs from Klebsiella pneumoniae (KpSSB), Salmonella enterica (StSSB), and Pseudomonas aeruginosa (PaSSB) were used to analyze the stimulation effect. Two chimeric proteins, namely, KpSSBn-PaSSBc and KpSSBn-StSSBc, were also used. KpSSB, StSSB, and KpSSBn-StSSBc can stimulate KpPriA activity, but PaSSB and KpSSBn-PaSSBc cannot. The crystal structure of PaSSB solved at 2.04 Å resolution (PDB entry 5YUO) reveals the classic OB fold structure, similar to that of EcSSB. Comparison of SSBs through sequence analysis showed that the typical glycine-rich flexible region in PaSSB contains very few glycine residues. Through analyses of protein chimeragenesis, structure–sequence, and ATPase stimulation effects, we concluded that the inherent difference in the glycine-rich flexible region among SSB species is a determinant of PriA stimulation. Further research can directly focus on determining the type of glycine-rich hinge that can stimulate PriA and the reason why bacterial SSBs need to evolve different C-terminal domains during evolution. Single-stranded DNA-binding protein (SSB) is essential for all DNA-dependent cellular processes.![]()
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Affiliation(s)
- Yen-Hua Huang
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
| | - Cheng-Yang Huang
- School of Biomedical Sciences
- Chung Shan Medical University
- Taichung City
- Taiwan
- Department of Medical Research
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19
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Neamah MM, Mir-Sanchis I, López-Sanz M, Acosta S, Baquedano I, Haag AF, Marina A, Ayora S, Penadés JR. Sak and Sak4 recombinases are required for bacteriophage replication in Staphylococcus aureus. Nucleic Acids Res 2017; 45:6507-6519. [PMID: 28475766 PMCID: PMC5499656 DOI: 10.1093/nar/gkx308] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 05/03/2017] [Indexed: 11/16/2022] Open
Abstract
DNA-single strand annealing proteins (SSAPs) are recombinases frequently encoded in the genome of many bacteriophages. As SSAPs can promote homologous recombination among DNA substrates with an important degree of divergence, these enzymes are involved both in DNA repair and in the generation of phage mosaicisms. Here, analysing Sak and Sak4 as representatives of two different families of SSAPs present in phages infecting the clinically relevant bacterium Staphylococcus aureus, we demonstrate for the first time that these enzymes are absolutely required for phage reproduction. Deletion of the genes encoding these enzymes significantly reduced phage replication and the generation of infectious particles. Complementation studies revealed that these enzymes are required both in the donor (after prophage induction) and in the recipient strain (for infection). Moreover, our results indicated that to perform their function SSAPs require the activity of their cognate single strand binding (Ssb) proteins. Mutational studies demonstrated that the Ssb proteins are also required for phage replication, both in the donor and recipient strain. In summary, our results expand the functions attributed to the Sak and Sak4 proteins, and demonstrate that both SSAPs and Ssb proteins are essential for the life cycle of temperate staphylococcal phages.
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Affiliation(s)
- Maan M Neamah
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK.,Department of Microbiology, Faculty of Veterinary Medicine, University of Kufa, Kufa, Iraq
| | - Ignacio Mir-Sanchis
- Departamento de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, 46113 Moncada, Valencia, Spain
| | - María López-Sanz
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 28049 Madrid, Spain
| | - Sonia Acosta
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 28049 Madrid, Spain
| | - Ignacio Baquedano
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 28049 Madrid, Spain
| | - Andreas F Haag
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK
| | - Alberto Marina
- Instituto de Biomedicina de Valencia (IBV-CSIC) and CIBER de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 28049 Madrid, Spain
| | - José R Penadés
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK
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20
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Reiche MA, Warner DF, Mizrahi V. Targeting DNA Replication and Repair for the Development of Novel Therapeutics against Tuberculosis. Front Mol Biosci 2017; 4:75. [PMID: 29184888 PMCID: PMC5694481 DOI: 10.3389/fmolb.2017.00075] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 10/31/2017] [Indexed: 12/11/2022] Open
Abstract
Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), an infectious disease which results in approximately 10 million incident cases and 1.4 million deaths globally each year, making it the leading cause of mortality from infection. An effective frontline combination chemotherapy exists for TB; however, this regimen requires the administration of four drugs in a 2 month long intensive phase followed by a continuation phase of a further 4 months with two of the original drugs, and is only effective for the treatment of drug-sensitive TB. The emergence and global spread of multidrug-resistant (MDR) as well as extensively drug-resistant (XDR) strains of M. tuberculosis, and the complications posed by co-infection with the human immunodeficiency virus (HIV) and other co-morbidities such as diabetes, have prompted urgent efforts to develop shorter regimens comprising new compounds with novel mechanisms of action. This demands that researchers re-visit cellular pathways and functions that are essential to M. tuberculosis survival and replication in the host but which are inadequately represented amongst the targets of current anti-mycobacterial agents. Here, we consider the DNA replication and repair machinery as a source of new targets for anti-TB drug development. Like most bacteria, M. tuberculosis encodes a complex array of proteins which ensure faithful and accurate replication and repair of the chromosomal DNA. Many of these are essential; so, too, are enzymes in the ancillary pathways of nucleotide biosynthesis, salvage, and re-cycling, suggesting the potential to inhibit replication and repair functions at multiple stages. To this end, we provide an update on the state of chemotherapeutic inhibition of DNA synthesis and related pathways in M. tuberculosis. Given the established links between genotoxicity and mutagenesis, we also consider the potential implications of targeting DNA metabolic pathways implicated in the development of drug resistance in M. tuberculosis, an organism which is unusual in relying exclusively on de novo mutations and chromosomal rearrangements for evolution, including the acquisition of drug resistance. In that context, we conclude by discussing the feasibility of targeting mutagenic pathways in an ancillary, “anti-evolution” strategy aimed at protecting existing and future TB drugs.
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Affiliation(s)
- Michael A Reiche
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Digby F Warner
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Valerie Mizrahi
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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