scholarly journals Structural basis for DNA 5´-end resection by RecJ

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Kaiying Cheng ◽  
Hong Xu ◽  
Xuanyi Chen ◽  
Liangyan Wang ◽  
Bing Tian ◽  
...  
Keyword(s):  
Active Site ◽  
Deinococcus Radiodurans ◽  
Divalent Cations ◽  
Binding Pocket ◽  
Structural Basis ◽  
Phosphate Binding ◽  
Terminal Domain ◽  
Dna Strand ◽  
Recombination Pathway ◽  
End Resection

The resection of DNA strand with a 5´ end at double-strand breaks is an essential step in recombinational DNA repair. RecJ, a member of DHH family proteins, is the only 5´ nuclease involved in the RecF recombination pathway. Here, we report the crystal structures of Deinococcus radiodurans RecJ in complex with deoxythymidine monophosphate (dTMP), ssDNA, the C-terminal region of single-stranded DNA-binding protein (SSB-Ct) and a mechanistic insight into the RecF pathway. A terminal 5´-phosphate-binding pocket above the active site determines the 5´-3´ polarity of the deoxy-exonuclease of RecJ; a helical gateway at the entrance to the active site admits ssDNA only; and the continuous stacking interactions between protein and nine nucleotides ensure the processive end resection. The active site of RecJ in the N-terminal domain contains two divalent cations that coordinate the nucleophilic water. The ssDNA makes a 180° turn at the scissile phosphate. The C-terminal domain of RecJ binds the SSB-Ct, which explains how RecJ and SSB work together to efficiently process broken DNA ends for homologous recombination.

scholarly journals Structural basis for UCN-01 (7-hydroxystaurosporine) specificity and PDK1 (3-phosphoinositide-dependent protein kinase-1) inhibition

2003 ◽  
Vol 375 (2) ◽  
pp. 255-262 ◽  
Author(s):  
David KOMANDER ◽  
Gursant S. KULAR ◽  
Jennifer BAIN ◽  
Matthew ELLIOTT ◽  
Dario R. ALESSI ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Hydroxy Group ◽  
Active Site ◽  
Binding Pocket ◽  
Kinase Domain ◽  
Structural Basis ◽  
Active Site Residues ◽  
Dependent Protein Kinase ◽  
Growth Factor Signalling ◽  
Dependent Protein

PDK1 (3-phosphoinositide-dependent protein kinase-1) is a member of the AGC (cAMP-dependent, cGMP-dependent, protein kinase C) family of protein kinases, and has a key role in insulin and growth-factor signalling through phosphorylation and subsequent activation of a number of other AGC kinase family members, such as protein kinase B. The staurosporine derivative UCN-01 (7-hydroxystaurosporine) has been reported to be a potent inhibitor for PDK1, and is currently undergoing clinical trials for the treatment of cancer. Here, we report the crystal structures of staurosporine and UCN-01 in complex with the kinase domain of PDK1. We show that, although staurosporine and UCN-01 interact with the PDK1 active site in an overall similar manner, the UCN-01 7-hydroxy group, which is not present in staurosporine, generates direct and water-mediated hydrogen bonds with active-site residues. Inhibition data from UCN-01 tested against a panel of 29 different kinases show a different pattern of inhibition compared with staurosporine. We discuss how these differences in inhibition could be attributed to specific interactions with the additional 7-hydroxy group, as well as the size of the 7-hydroxy-group-binding pocket. This information could lead to opportunities for structure-based optimization of PDK1 inhibitors.

scholarly journals High-Resolution Crystal Structure of the Subclass B3 Metallo-β-Lactamase BJP-1: Rational Basis for Substrate Specificity and Interaction with Sulfonamides

2010 ◽  
Vol 54 (10) ◽  
pp. 4343-4351 ◽  
Author(s):  
Jean-Denis Docquier ◽  
Manuela Benvenuti ◽  
Vito Calderone ◽  
Magdalena Stoczko ◽  
Nicola Menciassi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Bradyrhizobium Japonicum ◽  
Active Sites ◽  
Structural Diversity ◽  
Binding Pocket ◽  
Structural Basis ◽  
Side Chain ◽  
Functional Heterogeneity ◽  
Hydrophobic Binding

ABSTRACT Metallo-β-lactamases (MBLs) are important enzymatic factors in resistance to β-lactam antibiotics that show important structural and functional heterogeneity. BJP-1 is a subclass B3 MBL determinant produced by Bradyrhizobium japonicum that exhibits interesting properties. BJP-1, like CAU-1 of Caulobacter vibrioides, overall poorly recognizes β-lactam substrates and shows an unusual substrate profile compared to other MBLs. In order to understand the structural basis of these properties, the crystal structure of BJP-1 was obtained at 1.4-Å resolution. This revealed significant differences in the conformation and locations of the active-site loops, determining a rather narrow active site and the presence of a unique N-terminal helix bearing Phe-31, whose side chain binds in the active site and represents an obstacle for β-lactam substrate binding. In order to probe the potential of sulfonamides (known to inhibit various zinc-dependent enzymes) to bind in the active sites of MBLs, the structure of BJP-1 in complex with 4-nitrobenzenesulfonamide was also obtained (at 1.33-Å resolution), thereby revealing the mode of interaction of these molecules in MBLs. Interestingly, sulfonamide binding resulted in the displacement of the side chain of Phe-31 from its hydrophobic binding pocket, where the benzene ring of the molecule is now found. These data further highlight the structural diversity shown by MBLs but also provide interesting insights in the structure-function relationships of these enzymes. More importantly, we provided the first structural observation of MBL interaction with sulfonamides, which might represent an interesting scaffold for the design of MBL inhibitors.

scholarly journals Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I

2017 ◽  
Vol 114 (23) ◽  
pp. 6010-6015 ◽  
Author(s):  
Yuqian Shi ◽  
Homme W. Hellinga ◽  
Lorena S. Beese
Keyword(s):  
Conformational Changes ◽  
Active Site ◽  
Structural Basis ◽  
Reaction Sequence ◽  
Exonuclease I ◽  
Endonucleolytic Cleavage ◽  
Transition State Stabilization ◽  
Before And After ◽  
Exonuclease 1 ◽  
Dna Strand

Human exonuclease 1 (hExo1) is a member of the RAD2/XPG structure-specific 5′-nuclease superfamily. Its dominant, processive 5′–3′ exonuclease and secondary 5′-flap endonuclease activities participate in various DNA repair, recombination, and replication processes. A single active site processes both recessed ends and 5′-flap substrates. By initiating enzyme reactions in crystals, we have trapped hExo1 reaction intermediates that reveal structures of these substrates before and after their exo- and endonucleolytic cleavage, as well as structures of uncleaved, unthreaded, and partially threaded 5′ flaps. Their distinctive 5′ ends are accommodated by a small, mobile arch in the active site that binds recessed ends at its base and threads 5′ flaps through a narrow aperture within its interior. A sequence of successive, interlocking conformational changes guides the two substrate types into a shared reaction mechanism that catalyzes their cleavage by an elaborated variant of the two-metal, in-line hydrolysis mechanism. Coupling of substrate-dependent arch motions to transition-state stabilization suppresses inappropriate or premature cleavage, enhancing processing fidelity. The striking reduction in flap conformational entropy is catalyzed, in part, by arch motions and transient binding interactions between the flap and unprocessed DNA strand. At the end of the observed reaction sequence, hExo1 resets without relinquishing DNA binding, suggesting a structural basis for its processivity.

3′-Azidothymidine in the active site ofEscherichia colithymidine phosphorylase: the peculiarity of the binding on the basis of X-ray study

2014 ◽  
Vol 70 (4) ◽  
pp. 1155-1165 ◽  
Author(s):  
Vladimir Timofeev ◽  
Yulia Abramchik ◽  
Nadezda Zhukhlistova ◽  
Tatiana Muravieva ◽  
Ilya Fateev ◽  
...  
Keyword(s):  
Active Site ◽  
Thymidine Phosphorylase ◽  
Binding Pocket ◽  
Chemotherapeutic Agents ◽  
Nucleoside Analogues ◽  
Dimensional Structure ◽  
Phosphate Binding ◽  
X Ray ◽  
E Coli ◽  
Replacement Method

The structural study of complexes of thymidine phosphorylase (TP) with nucleoside analogues which inhibit its activity is of special interest because many of these compounds are used as chemotherapeutic agents. Determination of kinetic parameters showed that 3′-azido-3′-deoxythymidine (3′-azidothymidine; AZT), which is widely used for the treatment of human immunodeficiency virus, is a reversible noncompetitive inhibitor ofEscherichia colithymidine phosphorylase (TP). The three-dimensional structure ofE. coliTP complexed with AZT was solved by the molecular-replacement method and was refined at 1.52 Å resolution. Crystals for X-ray study were grown in microgravity by the counter-diffusion technique from a solution of the protein in phosphate buffer with ammonium sulfate as a precipitant. The AZT molecule was located with full occupancy in the electron-density maps in the nucleoside-binding pocket of TP, whereas the phosphate-binding pocket of the enzyme was occupied by phosphate (or sulfate) ion. The structure of the active-site cavity and conformational changes of the enzyme upon AZT binding are described in detail. It is found that the position of AZT differs remarkably from the positions of the pyrimidine bases and nucleoside analogues in other known complexes of pyrimidine phosphorylases, but coincides well with the position of 2′-fluoro-3′-azido-2′,3′-dideoxyuridine (N3FddU) in the recently investigated complex ofE. coliTP with this ligand (Timofeevet al., 2013). The peculiarities of the arrangement of N3FddU and 3′-azidothymidine in the nucleoside binding pocket of TP and correlations between the arrangement and inhibitory properties of these compounds are discussed.

scholarly journals Investigating the role of N-terminal domain in phosphodiesterase 4B-inhibition by molecular dynamics simulation

2020 ◽  
Author(s):  
Vidushi Sharma ◽  
Sharad Wakode
Keyword(s):  
Ligand Binding ◽  
Root Mean Square ◽  
Active Site ◽  
Binding Pocket ◽  
Dynamics Simulation ◽  
Radius Of Gyration ◽  
Mean Square ◽  
Sequence Identity ◽  
Terminal Domain ◽  
Phosphodiesterase 4B

AbstractPhosphodiesterase 4B (PDE4B) is a potential therapeutic target for the inflammatory respiratory diseases such as congestive obstructive pulmonary disease (COPD) and asthma. The sequence identity of ∼88% with its isoform PDE4D is the key barrier in developing selective PDE4B inhibitors which may help to overcome associated side effects. Despite high sequence identity, both isoforms differ in few residues present in N-terminal (UCR2) and C-terminal (CR3) involved in catalytic site formation. Previously, we designed and tested specific PDE4B inhibitors considering N-terminal residues as a part of the catalytic cavity. In continuation, current work thoroughly presents an MD simulation-based analysis of N-terminal residues and their role in ligand binding. The various parameters viz. root mean square deviation (RMSD), radius of gyration (Rg), root mean square fluctuation (RMSF), principal component analysis (PCA), dynamical cross-correlation matrix (DCCM) analysis, secondary structure analysis, and residue interaction mapping were investigated to establish rational. Results showed that UCR2 reduced RMSF values for the metal binding pocket (31.5±11 to 13.12±6 Å2) and the substrate-binding pocket (38.8±32 to 17.3±11 Å2). UCR2 enhanced anti-correlated motion at the active site region that led to the improved ligand-binding affinity of PDE4B from −24.57±3 to −35.54±2 kcal/mol. Further, the atomic-level analysis indicated that T-pi and π-π interactions between inhibitors and residues are vital forces that regulate inhibitor association to PDE4B with high affinity. In conclusion, UCR2, the N-terminal domain, embraces the dynamics of PDE4B active site and stabilizes PDE4B inhibitor interactions. Therefore the N-terminal domain needs to be included by designing next-generation, selective PDE4B-inhibitors as potential anti-inflammatory drugs.

Structural and kinetic differences between human and Aspergillus fumigatusD-glucosamine-6-phosphate N-acetyltransferase

2008 ◽  
Vol 415 (2) ◽  
pp. 217-223 ◽  
Author(s):  
Ramon Hurtado-Guerrero ◽  
Olawale G. Raimi ◽  
Jinrong Min ◽  
Hong Zeng ◽  
Laura Vallius ◽  
...  
Keyword(s):  
Active Site ◽  
Gene Disruption ◽  
Biosynthetic Pathway ◽  
Binding Pocket ◽  
Immunocompromised Patients ◽  
Kinetic Characterization ◽  
Phosphate Binding ◽  
Fungal Enzyme ◽  
Pathway Gene ◽  
Steady State Kinetics

Aspergillus fumigatus is the causative agent of aspergillosis, a frequently invasive colonization of the lungs of immunocompromised patients. GNA1 (D-glucosamine-6-phosphate N-acetyltransferase) catalyses the acetylation of GlcN-6P (glucosamine-6-phosphate) to GlcNAc-6P (N-acetylglucosamine-6-phosphate), a key intermediate in the UDP-GlcNAc biosynthetic pathway. Gene disruption of gna1 in yeast and Candida albicans has provided genetic validation of the enzyme as a potential target. An understanding of potential active site differences between the human and A. fumigatus enzymes is required to enable further work aimed at identifying selective inhibitors for the fungal enzyme. In the present study, we describe crystal structures of both human and A. fumigatus GNA1, as well as their kinetic characterization. The structures show significant differences in the sugar-binding site with, in particular, several non-conservative substitutions near the phosphate-binding pocket. Mutagenesis targeting these differences revealed drastic effects on steady-state kinetics, suggesting that the differences could be exploitable with small-molecule inhibitors.

scholarly journals One enzyme, many reactions: structural basis for the various reactions catalyzed by naphthalene 1,2-dioxygenase

IUCrJ ◽  
2017 ◽  
Vol 4 (5) ◽  
pp. 648-656 ◽  
Author(s):  
Daniel J. Ferraro ◽  
Adam Okerlund ◽  
Eric Brown ◽  
S. Ramaswamy
Keyword(s):  
Active Site ◽  
Binding Pocket ◽  
Nonheme Iron ◽  
Structural Basis ◽  
Mononuclear Iron

Rieske nonheme iron oxygenases (ROs) are a well studied class of enzymes. Naphthalene 1,2-dioxygenase (NDO) is used as a model to study ROs. Previous work has shown how side-on binding of oxygen to the mononuclear iron provides this enzyme with the ability to catalyze stereospecific and regiospecificcis-dihydroxylation reactions. It has been well documented that ROs catalyze a variety of other reactions, including mono-oxygenation, desaturation, O- and N-dealkylation, sulfoxidationetc. NDO itself catalyzes a variety of these reactions. Structures of NDO in complex with a number of different substrates show that the orientation of the substrate in the active site controls not only the regiospecificity and stereospecificity, but also the type of reaction catalyzed. It is proposed that the mononuclear iron-activated dioxygen attacks the atoms of the substrate that are most proximal to it. The promiscuity of delivering two products (apparently by two different reactions) from the same substrate can be explained by the possible binding of the substrate in slightly different orientations aided by the observed flexibility of residues in the binding pocket.

Structural basis for the regulation of chemotaxis by MapZ in the presence of c-di-GMP

2017 ◽  
Vol 73 (8) ◽  
pp. 683-691 ◽  
Author(s):  
Yingxiao Zhu ◽  
Zenglin Yuan ◽  
Lichuan Gu
Keyword(s):  
Binding Site ◽  
Crystal Structures ◽  
Second Messenger ◽  
Binding Pocket ◽  
Single Domain ◽  
Structural Basis ◽  
Cyclic Diguanylate ◽  
Bacterial Physiology ◽  
Terminal Domain ◽  
Mechanism Of Inhibition

The bacterial second messenger cyclic diguanylate monophosphate (c-di-GMP) mediates multiple aspects of bacterial physiology through binding to various effectors. In some cases, these effectors are single-domain proteins which only contain a PilZ domain. It remains largely unknown how single-domain PilZ proteins function and regulate their downstream targets. Recently, a single-domain PilZ protein, MapZ (PA4608), was identified to inhibit the activity of the methyltransferase CheR1. Here, crystal structures of the C-terminal domain of CheR1 containing SAH and of CheR1 in complex with c-di-GMP-bound MapZ are reported. It was observed that the binding site of MapZ in CheR1 partially overlaps with the SAH/SAM-binding pocket. Consequently, binding of MapZ blocks SAH/SAM binding. This provides direct structural evidence on the mechanism of inhibition of CheR1 by MapZ in the presence of c-di-GMP.

scholarly journals Mechanistic and structural basis for inhibition of thymidylate synthase ThyX

Open Biology ◽  
2012 ◽  
Vol 2 (10) ◽  
pp. 120120 ◽  
Author(s):  
Tamara Basta ◽  
Yap Boum ◽  
Julien Briffotaux ◽  
Hubert F. Becker ◽  
Isabelle Lamarre-Jouenne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Tight Binding ◽  
Binding Pocket ◽  
Structural Basis ◽  
Microbial Genomes ◽  
Thymidylate Synthases ◽  
Thymidylate Synthesis

Nature has established two mechanistically and structurally unrelated families of thymidylate synthases that produce de novo thymidylate or dTMP, an essential DNA precursor. Representatives of the alternative flavin-dependent thymidylate synthase family, ThyX, are found in a large number of microbial genomes, but are absent in humans. We have exploited the nucleotide binding pocket of ThyX proteins to identify non-substrate-based tight-binding ThyX inhibitors that inhibited growth of genetically modified Escherichia coli cells dependent on thyX in a manner mimicking a genetic knockout of thymidylate synthase. We also solved the crystal structure of a viral ThyX bound to 2-hydroxy-3-(4-methoxybenzyl)-1,4-naphthoquinone at a resolution of 2.6 Å. This inhibitor was found to bind within the conserved active site of the tetrameric ThyX enzyme, at the interface of two monomers, partially overlapping with the dUMP binding pocket. Our studies provide new chemical tools for investigating the ThyX reaction mechanism and establish a novel mechanistic and structural basis for inhibition of thymidylate synthesis. As essential ThyX proteins are found e.g. in Mycobacterium tuberculosis and Helicobacter pylori , our studies have also potential to pave the way towards the development of new anti-microbial compounds.

scholarly journals Structural basis for the ARF GAP activity and specificity of the C9orf72 complex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ming-Yuan Su ◽  
Simon A. Fromm ◽  
Jonathan Remis ◽  
Daniel B. Toso ◽  
James H. Hurley
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Active Site ◽  
Binding Pocket ◽  
Structural Basis ◽  
Specific Function ◽  
Loss Of Function ◽  
Gtpase Activating Protein ◽  
Protein Activity ◽  
Mtorc1 Pathway ◽  
Lateral Sclerosis

AbstractMutation of C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontal temporal degeneration (FTD), which is attributed to both a gain and loss of function. C9orf72 forms a complex with SMCR8 and WDR41, which was reported to have GTPase activating protein activity toward ARF proteins, RAB8A, and RAB11A. We determined the cryo-EM structure of ARF1-GDP-BeF3- bound to C9orf72:SMCR8:WDR41. The SMCR8longin and C9orf72longin domains form the binding pocket for ARF1. One face of the C9orf72longin domain holds ARF1 in place, while the SMCR8longin positions the catalytic finger Arg147 in the ARF1 active site. Mutations in interfacial residues of ARF1 and C9orf72 reduced or eliminated GAP activity. RAB8A GAP required ~10-fold higher concentrations of the C9orf72 complex than for ARF1. These data support a specific function for the C9orf72 complex as an ARF GAP. The structure also provides a model for the active forms of the longin domain GAPs of FLCN and NPRL2 that regulate the Rag GTPases of the mTORC1 pathway.

Sign in / Sign up

Export Citation Format

Share Document