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Saeed MS, Siddiqui MA, Rashid N. Effect of Y50H and S187G substitutions on thermostability and exonuclease activity of TK1646 from Thermococcus kodakarensis. Protein Expr Purif 2020; 179:105799. [PMID: 33249274 DOI: 10.1016/j.pep.2020.105799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/17/2020] [Accepted: 11/20/2020] [Indexed: 10/22/2022]
Abstract
TK1646 is a highly thermostable single strand specific 3'-5' exonuclease. Exonucleases play important role in maintaining the genome integrity at elevated temperatures. Therefore, it is important to examine the factors contributing to thermostability of these exonucleases. In this study we report on production, purification and characterization of S187G and Y50H mutants of TK1646, focusing on the factors leading to thermostability of TK1646. Characterization of the recombinant proteins indicated that these substitutions did not drastically affect the catalysis of single stranded DNA. However, both of these substitutions reduced the thermostability of the recombinant proteins. Half-lives of Y50H and S187G mutants were 95 and 155 min, respectively, at 100 °C in comparison to 180 min of the wild type. Bioinformatics analysis indicated an increase in solvent accessibility of the mutated residues and disruption of hydrogens bonds. Molecular modelling and superimposition of the 3D structures of the mutants and the wild type demonstrated that one of the active site residues, Glu145, was shifted away from the metal ion in both the mutants which may be responsible for the decrease in catalytic activity. Compact secondary structure, hydrophobicity and hydrogen bonding might be the major factors contributing to the thermostability of TK1646.
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Affiliation(s)
| | | | - Naeem Rashid
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
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Structure and Mechanism of a Cyclic Trinucleotide-Activated Bacterial Endonuclease Mediating Bacteriophage Immunity. Mol Cell 2020; 77:723-733.e6. [PMID: 31932164 DOI: 10.1016/j.molcel.2019.12.010] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 10/04/2019] [Accepted: 12/12/2019] [Indexed: 12/26/2022]
Abstract
Bacteria possess an array of defenses against foreign invaders, including a broadly distributed bacteriophage defense system termed CBASS (cyclic oligonucleotide-based anti-phage signaling system). In CBASS systems, a cGAS/DncV-like nucleotidyltransferase synthesizes cyclic di- or tri-nucleotide second messengers in response to infection, and these molecules activate diverse effectors to mediate bacteriophage immunity via abortive infection. Here, we show that the CBASS effector NucC is related to restriction enzymes but uniquely assembles into a homotrimer. Binding of NucC trimers to a cyclic tri-adenylate second messenger promotes assembly of a NucC homohexamer competent for non-specific double-strand DNA cleavage. In infected cells, NucC activation leads to complete destruction of the bacterial chromosome, causing cell death prior to completion of phage replication. In addition to CBASS systems, we identify NucC homologs in over 30 type III CRISPR/Cas systems, where they likely function as accessory nucleases activated by cyclic oligoadenylate second messengers synthesized by these systems' effector complexes.
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Saeed MS, Rashid N. Characterization of TK1646, a highly thermostable 3'-5' single strand specific exonuclease from Thermococcus kodakarensis. Int J Biol Macromol 2019; 140:1194-1201. [PMID: 31437504 DOI: 10.1016/j.ijbiomac.2019.08.150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 08/02/2019] [Accepted: 08/17/2019] [Indexed: 10/26/2022]
Abstract
Exonucleases catalyze the hydrolysis of terminal phosphodiester bond in nucleic acid. They play important role in maintaining the integrity of DNA in eukaryotes, prokaryotes and archaea. Limited studies have been done on archaeal exonucleases. Here we report molecular cloning of TK1646, a putative exonuclease from the hyperthermophilic archaeon Thermococcus kodakarensis, and expression of the gene in Escherichia coli. Recombinant TK1646, produced in soluble and active form, was purified to apparent homogeneity. Characterization of the recombinant enzyme indicated that it was single strand specific 3'-5' exonuclease which cleaved the substrate DNA after every two nucleotides. It exhibited highest activity at 85-100 °C and pH 9.0. Unique property of TK1646 was its thermostability as it maintained its activity even at 100 °C with a half-life of 180 min. Recombinant TK1646 followed Michaelis-Menten kinetics and exhibited apparent Km and Vmax values of 33 ± 4 μM and 812 ± 48 nmol/min/mg, respectively. To the best of our knowledge this is the most thermostable single strand specific 3'-5' exonuclease characterized to date.
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Affiliation(s)
| | - Naeem Rashid
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan 54590.
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Miyazono KI, Ishino S, Makita N, Ito T, Ishino Y, Tanokura M. Crystal structure of the novel lesion-specific endonuclease PfuEndoQ from Pyrococcus furiosus. Nucleic Acids Res 2019; 46:4807-4818. [PMID: 29660024 PMCID: PMC5961232 DOI: 10.1093/nar/gky261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/28/2018] [Indexed: 02/03/2023] Open
Abstract
Because base deaminations, which are promoted by high temperature, ionizing radiation, aerobic respiration and nitrosative stress, produce mutations during replication, deaminated bases must be repaired quickly to maintain genome integrity. Recently, we identified a novel lesion-specific endonuclease, PfuEndoQ, from Pyrococcus furiosus, and PfuEndoQ may be involved in the DNA repair pathway in Thermococcales of Archaea. PfuEndoQ recognizes a deaminated base and cleaves the phosphodiester bond 5' of the lesion site. To elucidate the structural basis of the substrate recognition and DNA cleavage mechanisms of PfuEndoQ, we determined the structure of PfuEndoQ using X-ray crystallography. The PfuEndoQ structure and the accompanying biochemical data suggest that PfuEndoQ recognizes a deaminated base using a highly conserved pocket adjacent to a Zn2+-binding site and hydrolyses a phosphodiester bond using two Zn2+ ions. The PfuEndoQ-DNA complex is stabilized by a Zn-binding domain and a C-terminal helical domain, and the complex may recruit downstream proteins in the DNA repair pathway.
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Affiliation(s)
- Ken-Ichi Miyazono
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Naruto Makita
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Tomoko Ito
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Masaru Tanokura
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Feng L, Chang CC, Song D, Jiang C, Song Y, Wang CF, Deng W, Zou YJ, Chen HF, Xiao X, Wang FP, Liu XP. The trimeric Hef-associated nuclease HAN is a 3'→5' exonuclease and is probably involved in DNA repair. Nucleic Acids Res 2019; 46:9027-9043. [PMID: 30102394 PMCID: PMC6158738 DOI: 10.1093/nar/gky707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 08/01/2018] [Indexed: 12/26/2022] Open
Abstract
Nucleases play important roles in nucleic acid metabolism. Some archaea encode a conserved protein known as Hef-associated nuclease (HAN). In addition to its C-terminal DHH nuclease domain, HAN also has three N-terminal domains, including a DnaJ-Zinc-finger, ribosomal protein S1-like, and oligonucleotide/oligosaccharide-binding fold. To further understand HAN’s function, we biochemically characterized the enzymatic properties of HAN from Pyrococcus furiosus (PfuHAN), solved the crystal structure of its DHH nuclease domain, and examined its role in DNA repair. Our results show that PfuHAN is a Mn2+-dependent 3′-exonuclease specific to ssDNA and ssRNA with no activity on blunt and 3′-recessive double-stranded DNA. Domain truncation confirmed that the intrinsic nuclease activity is dependent on the C-terminal DHH nuclease domain. The crystal structure of the DHH nuclease domain adopts a trimeric topology, with each subunit adopting a classical DHH phosphoesterase fold. Yeast two hybrid assay confirmed that the DHH domain interacts with the IDR peptide of Hef nuclease. Knockout of the han gene or its C-terminal DHH nuclease domain in Haloferax volcanii resulted in increased sensitivity to the DNA damage reagent MMS. Our results imply that HAN nuclease might be involved in repairing stalled replication forks in archaea.
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Affiliation(s)
- Lei Feng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Chen-Chen Chang
- Institute of Precision Medicine,The Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine
| | - Dong Song
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Chuang Jiang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Yang Song
- Institute of Precision Medicine,The Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine
| | - Chao-Fan Wang
- Institute of Precision Medicine,The Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine
| | - Wei Deng
- Institute of Precision Medicine,The Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine
| | - Ya-Juan Zou
- Instrumental Analysis Center, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Hai-Feng Chen
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Xiang Xiao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China.,State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Feng-Ping Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China.,State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Xi-Peng Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China.,State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China
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Kim J, Sambalkhundev GO, Kim S, Son J, Han AR, Ko SM, Hwang KY, Lee WC. Processing of A-form ssDNA by cryptic RNase H fold exonuclease PF2046. Arch Biochem Biophys 2016; 606:143-50. [PMID: 27495739 DOI: 10.1016/j.abb.2016.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/29/2016] [Accepted: 08/01/2016] [Indexed: 11/18/2022]
Abstract
RNase H fold protein PF2046 of Pyrococcus furiosus is a 3'-5' ssDNA exonuclease that cleaves after the second nucleotide from the 3' end of ssDNA and prefers poly-dT over poly-dA as a substrate. In our crystal structure of PF2046 complexed with an oligonucleotide of four thymidine nucleotides (dT4), PF2046 accommodates dT4 tightly in a groove and imposes steric hindrance on dT4 mainly by Phe220 such that dT4 assumes the A-form. As poly-dA prefer B-form due to the stereochemical restrictions, the A-form ssDNA binding by PF2046 should disfavor the processing of poly-dA. Phe220 variants display reduced activity toward poly-dA and the A-form appears to be a prerequisite for the processing by PF2046.
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Affiliation(s)
- Junsoo Kim
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea; Institute for Life Sciences and Natural Resources, Korea University, Seoul 136-713, Republic of Korea
| | - Gerelt-Od Sambalkhundev
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea; Institute for Life Sciences and Natural Resources, Korea University, Seoul 136-713, Republic of Korea
| | - Sulhee Kim
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
| | - Jonghyeon Son
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
| | - Ah-Reum Han
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
| | - Sul-Min Ko
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
| | - Kwang Yeon Hwang
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea.
| | - Woo Cheol Lee
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-gu, Seoul 136-713, Republic of Korea; Institute for Life Sciences and Natural Resources, Korea University, Seoul 136-713, Republic of Korea.
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