structure in solution
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Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5776
Author(s):  
Qian Huang ◽  
Bo Duan ◽  
Zhi Qu ◽  
Shilong Fan ◽  
Bin Xia

The nucleoid-associated protein GapR found in Caulobacter crescentus is crucial for DNA replication, transcription, and cell division. Associated with overtwisted DNA in front of replication forks and the 3′ end of highly-expressed genes, GapR can stimulate gyrase and topo IV to relax (+) supercoils, thus facilitating the movement of the replication and transcription machines. GapR forms a dimer-of-dimers structure in solution that can exist in either an open or a closed conformation. It initially binds DNA through the open conformation and then undergoes structural rearrangement to form a closed tetramer, with DNA wrapped in the central channel. Here, we show that the DNA binding domain of GapR (residues 1–72, GapRΔC17) exists as a dimer in solution and adopts the same fold as the two dimer units in the full-length tetrameric protein. It binds DNA at the minor groove and reads the spatial distribution of DNA phosphate groups through a lysine/arginine network, with a preference towards AT-rich overtwisted DNA. These findings indicate that the dimer unit of GapR has an intrinsic DNA binding preference. Thus, at the initial binding step, the open tetramer of GapR with two relatively independent dimer units can be more efficiently recruited to overtwisted regions.


Author(s):  
Kazuhisa Miyazawa ◽  
Satoru G. Itoh ◽  
Hiroki Watanabe ◽  
Takayuki Uchihashi ◽  
Saeko Yanaka ◽  
...  

Author(s):  
Tatiana M. Makhova ◽  
◽  
Sergei Yu. Doronin ◽  

The sorption properties of glauconite from Beloozersk deposits (Saratov region) for 4-nitrophenol (4-NF) have been investigated. The effect of glauconite on pH and 4-nitrophenol structure in solution is estimated. It is shown that glauconite increases pH of aqueous environment to 8 and shifts the equilibrium towards the formation of aci-form 4-NF. The conditions of sorption 4-NF by glauconite are established: the sorption time 20 min, the mass of the sorbent (0.50–1.0) g. The isotherm of sorption by 4-NF glauconite has been obtained; its interpretation is given using the Langmuir and Freundlich equations. The main quantitative sorption characteristics of glauconite such as recovery (R = 64%), distribution coefficient (D = 88) and the Langmuir and Freundlich constants for 4-nitrophenol are calculated. These experiments indicate the potential use of the glauconite from Beloozersk deposits (Saratov region) for 4-NP from various waters.


2021 ◽  
Vol 133 (15) ◽  
pp. 8061-8061
Author(s):  
Francisco Rey‐Tarrío ◽  
Rafael Rodríguez ◽  
Emilio Quiñoá ◽  
Ricardo Riguera ◽  
Félix Freire

2021 ◽  
Vol 60 (15) ◽  
pp. 7985-7985
Author(s):  
Francisco Rey‐Tarrío ◽  
Rafael Rodríguez ◽  
Emilio Quiñoá ◽  
Ricardo Riguera ◽  
Félix Freire

2021 ◽  
Author(s):  
Paula Corsini ◽  
Sunjun Wang ◽  
Saima Rehman ◽  
Katherine Fenn ◽  
Amin Sagar ◽  
...  

Abstract Escherichia coli is a Gram-negative bacterium that colonizes the human intestine and virulent strains can cause severe diarrhoeal and extraintestinal diseases. The protein SslE is secreted by a range of pathogenic and some commensal E. coli strains. It can degrade mucins in the intestine, promotes biofilm maturation and in virulent strains, it is a major determinant of infection, although how it carries out these functions is not well understood. Here we examine SslE from the E. coli Waksman and H10407 strains and show that SslE has a highly dynamic structure in solution. We directly observe acidification within mature biofilms, describe a mechanism where SslE forms unique functional fibres under these conditions and determine that these SslE aggregates can bind cellulose, a major exopolysaccharide of many E. coli biofilms. Our data indicates that the spatial organization of SslE polymers and local pH are critical for biofilm maturation and SslE is a key factor that drives persistence of SslE-secreting bacteria during acidic stress.


Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 222
Author(s):  
Mio Matsumura ◽  
Yuki Matsuhashi ◽  
Masato Kawakubo ◽  
Tadashi Hyodo ◽  
Yuki Murata ◽  
...  

The expectation that antimony (Sb) compounds should display phosphorescence emissions based on the “heavy element effect” prompted our interest in the introduction of antimony to a biaryl as the bridging atom in a fused heterole system. Herein, the synthesis, molecular structures, and optical properties of novel benzene-fused heteroacenes containing antimony or arsenic atoms are described. The stiboles and arsole were prepared by the condensation of dibromo(phenyl)stibane or dichloro(phenyl)arsine with dilithium intermediates derived from the corresponding dibromo compounds. Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystal analysis revealed that the linear pentacyclic stibole was highly symmetric in both the solution and crystal states. In contrast, the curved pentacyclic stibole adopted a helical structure in solution, and surprisingly, only M helical molecules were crystallized from the racemate. All synthesized compounds produced very weak or no emissions at room temperature or in the solid state. In contrast, the linear penta- and tetracyclic stiboles exhibited clear phosphorescence emissions in the CHCl3 frozen matrix at 77 K under aerobic conditions.


2021 ◽  
Author(s):  
Anton D Kovalenko ◽  
Alexander A. Pavlov ◽  
Ilya D. Ustinovich ◽  
Alena S. Kalyakina ◽  
Alexander S Goloveshkin ◽  
...  

Abstract: Solution behaviour in DMSO using 1D and 2D NMR spectroscopy was performed for lanthanide complexes Ln(L)(HL) and Ln(HL)2Cl, containing non-macrocyclic 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), and the structure of [Yb(L)]+ cation in...


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