The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death.

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RECQ1 is the shortest among the five human RecQ helicases comprising of two RecA like domains, a zinc-binding domain and a RecQ C-terminal domain containing the winged-helix (WH). Mutations or deletions on the tip of a β-hairpin located in the WH domain are known to abolish the unwinding activity. Interestingly, the same mutations on the β-hairpin of annealing incompetent RECQ1 mutant (RECQ1T1) have been reported to restore its annealing activity. In an attempt to unravel the strand annealing mechanism, we have crystallized a fragment of RECQ1 encompassing D2–Zn–WH domains harbouring mutations on the β-hairpin. From our crystal structure data and interface analysis, we have demonstrated that an α-helix located in zinc-binding domain potentially interacts with residues of WH domain, which plays a significant role in strand annealing activity. We have shown that deletion of the α-helix or mutation of specific residues on it restores strand annealing activity of annealing deficient constructs of RECQ1. Our results also demonstrate that mutations on the α-helix induce conformational changes and affects DNA stimulated ATP hydrolysis and unwinding activity of RECQ1. Our study, for the first time, provides insight into the conformational requirements of the WH domain for efficient strand annealing by human RECQ1.

Decorating artificial nanomaterials for selective interaction of targets without the use of expensive antibodies or multistep molecules is of great interest in the applications of drug delivery and nanomedicine. Here, we designed a graphene oxide (GO)-based modified platform (GFM) having considerable photoluminescence (PL), which was further chemically modulated for the selective detection of a particular DNA base. In specific, GO was functionalized (GFM) with 5-aminophenanthroline (5-AP) by the heterogeneous azo coupling reaction. Then, the PL of the decorated GFM has been fully quenched by Cu(II) ions having maximum quenching efficiency. Finally, the quenched PL has been recovered by adenine molecules with high selectivity and negligible interference among various competitive biologically relevant ions and molecules. The quantum yields (Φ) and excited-state lifetime data nicely corroborate with the interaction between adenine and the GFM-Cu(II) material. This noncytotoxic material can estimate adenine as low as 4.6 × 10 −7 M in aqueous solution.