Lhr is a large superfamily 2 helicase present in mycobacteria and a moderate range of other bacterial taxa. A shorter version of Lhr, here referred to as Lhr-Core, is distributed widely in bacteria, where it is often encoded in a gene cluster along with predicted binuclear metallo-phosphoesterase (MPE), ATP-dependent DNA ligase, and metallo-β-lactamase exonuclease enzymes. Here we characterized the Lhr-Core and MPE proteins from We report that Lhr-Core is an ssDNA-dependent ATPase/dATPase ( , 0.37 mm ATP; , 3.3 s), an ATP-dependent 3'-to-5' single-stranded DNA translocase, and an ATP-dependent 3'-to-5' helicase. Lhr-Core unwinds 3'-tailed duplexes in which the loading/tracking strand is DNA and the displaced strand is either DNA or RNA. We found that MPE is a manganese-dependent phosphodiesterase that releases-nitrophenol from bis--nitrophenyl phosphate ( , 212 s) and -nitrophenyl-5'-thymidylate ( , 34 s) but displays no detectable phosphomonoesterase activity against -nitrophenyl phosphate. MPE is also a manganese-dependent DNA endonuclease that sequentially converts a closed-circle plasmid DNA to nicked circle and linear forms prior to degrading the linear DNA to produce progressively smaller fragments. The biochemical activities of MPE and a structure predicted in Phyre2 point to MPE as a new bacterial homolog of Mre11. Genetic linkage of a helicase and DNA nuclease with a ligase and a putative exonuclease (a predicted homolog of the SNM1/Apollo family of nucleases) suggests that these enzymes comprise or participate in a bacterial DNA repair pathway.
Mycobacterial Lhr is a DNA damage-inducible superfamily 2 helicase that uses adenosine triphosphate (ATP) hydrolysis to drive unidirectional 3′-to-5′ translocation along single-stranded DNA (ssDNA) and to unwind RNA:DNA duplexes en route. ATPase, translocase and helicase activities are encompassed within the N-terminal 856-amino acid segment. The crystal structure of Lhr-(1–856) in complex with AMPPNP•Mg2+ and ssDNA defines a new helicase family. The enzyme comprises two N-terminal RecA-like modules, a winged helix (WH) domain and a unique C-terminal domain. The 3′ ssDNA end binds in a crescent-shaped groove at the interface between the first RecA domain and the WH domain and tracks 5′ into a groove between the second RecA and C domains. A kissing interaction between the second RecA and C domains forms an aperture that demarcates a putative junction between the loading strand tail and the duplex, with the first duplex nucleoside bookended by stacking on Trp597. Intercalation of Ile528 between nucleosides of the loading strand creates another bookend. Coupling of ATP hydrolysis to RNA:DNA unwinding is dependent on Trp597 and Ile528, and on Thr145 and Arg279 that contact phosphates of the loading strand. The structural and functional data suggest a ratchet mechanism of translocation and unwinding coupled to ATP-driven domain movements.
A recently identified and widely prevalent prokaryal gene cluster encodes a suite of enzymes with imputed roles in nucleic acid repair. The enzymes are as follows: MPE, a DNA endonuclease; Lhr-Core, a 3-5 DNA helicase; LIG, an ATP-dependent DNA ligase; and Exo, a metallo--lactamase-family nuclease. Bacterial and archaeal MPE proteins belong to the binuclear metallophosphoesterase superfamily that includes the wellstudied DNA repair nucleases Mre11 and SbcD. Here, we report that the Pseudomonas putida MPE protein is a manganese-dependent DNA endonuclease that incises either linear single strands or the single-strand loops of stem-loop DNA structures. MPE has feeble activity on duplex DNA. A crystal structure of MPE at 2.2 Å resolution revealed that the active site includes two octahedrally coordinated manganese ions. Seven signature amino acids of the binuclear metallophosphoesterase superfamily serve as the enzymic metal ligands in MPE: Asp 33 , His 35 , Asp 78 , Asn 112 , His 124 , His 146 , and His 158 . A swath of positive surface potential on either side of the active site pocket suggests a binding site for the single-strand DNA substrate. The structure of MPE differs from Mre11 and SbcD in several key respects: (i) MPE is a monomer, whereas Mre11 and SbcD are homodimers; (ii) MPE lacks the capping domain present in Mre11 and SbcD; and (iii) the topology of the  sandwich that comprises the core of the metallophosphoesterase fold differs in MPE vis-à-vis Mre11 and SbcD. We surmise that MPE exemplifies a novel clade of DNA endonuclease within the binuclear metallophosphoesterase superfamily. cro ARTICLE
This work includes green synthesis of magnesium oxide nanoparticles (MgO NPs) by using Alstoniascholaris, which is indigenous to many countries such as China, Australia, Sri Lanka, Pakistan, and India. Its pharmacological activities include antidiabetic, antioxidant, anticancer, analgesic, antitussive, and anti-diarrheal activities. In this study, the antioxidant and anti-inflammatory activities of bio-inspired magnesium oxide nanoparticles, MgO NPs, were investigated. MgO NPs were prepared by using the leaf extract of Alstonia scholaris, followed by characterization using EDX, XRD, and SEM techniques. The crystallite size of magnesium oxide nanoparticles was 19.57 nm. XRD analysis confirmed the crystallinity and the purity of MgO NPs. Anti-inflammatory activity was carried out to observe inhibition of protein denaturation. Since the IC50 of MgO nanoparticles was lower than the standard, it was found to be more effective. IC50 values were compared, and results reveal that bioinspired MgO NPs undergo more scavenging of free radicals than standard (ascorbic acid) MgO NPs. These MgO nanoparticles are useful in cosmetics such as scrubs, moisturizers, and an active ingredient in microdermabrasion and in formulating effective drugs for maintaining the protein structure of the body, which will reduce inflammation.
Objective: The aim of this study was to assess the perceptions of different healthcare professionals towards HM. Methods: The 16-item questionnaire on the belief of health care professionals in herbal medicine was designed by the interdisciplinary task force. Eligible participants were health care providers who were English-and Arabic-literate. The response rate was 78% of participants (781 of 1000) were respondents. In total, 553 out of 781 (71%) participants indicated that they had previously used herbal medicines. The remaining 228 participants did not believe in herbal medicine due to lack of scientific evidence, ineffectiveness and other reasons. Results: The findings of this study indicate that health care professionals including pharmacists believe they have a responsibility to provide information on HM to their patients. However, the current consensus among the respondents is that current HM-focused knowledge is inadequate for such an application. Conclusion: Health care professionals believe in using HM for their needs and have a responsibility to provide information on HM to their patients.
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