Dependence of the nature of the Holstein polaron motion in a polynucleotide chain subjected to a constant electric field on the initial polaron state and the parameters of the chain

In this work, we consider the motion of a polaron in a polynucleotide Holstein molecular chain in a constant electric field. It is shown that the character of the polaron motion in the chain depends not only on the chosen parameters of the chain, but also on the initial distribution of the charge along the chain. It is shown that for a small set value of the electric field intensity and for fixed values of the chain parameters, changing only the initial distribution of the charge in the chain, it is possible to observe either a uniform movement of the charge along the chain, or an oscillatory mode of charge movement.

Recognize and Manipulate Pressure to Influence How Components Will Self-Assemble

How can we engineer components to assemble into complex structures in a reliable manner? Experimental methods rely on interactions such as surface properties, magnetic dipoles, charge, and polarizability. Here pressure is shown to have the power to hold a system together, or to take it apart. Specific diagrams give visual clues to the nature of the pressure that is present. The ability to identify the properties of pressure will allow researchers to manipulate pressure’s power to their advantage. DNA base pairing, polynucleotide chain properties, and an enzyme-catalyzed reaction are used as examples of self-assembling structures conforming to laws of pressure.

Posttranscriptional Modifications in 16S and 23S rRNAs of the Archaeal Hyperthermophile Sulfolobus solfataricus

ABSTRACT Posttranscriptional modification is common to many types of RNA, but the majority of information concerning structure and function of modification is derived principally from tRNA. By contrast, less is known about modification in rRNA in spite of accumulating evidence for its direct participation in translation. The structural identities and approximate molar levels of modifications have been established for 16S and 23S rRNAs of the archaeal hyperthermophile Sulfolobus solfactaricus by using combined chromatography-mass spectrometry-based methods. Modification levels are exceptionally high for prokaryotic organisms, with approximately 38 modified sites in 16S rRNA and 50 in 23S rRNA for cells cultured at 75°C, compared with 11 and 23 sites, respectively, in Escherichia coli. We structurally characterized 10 different modified nucleosides in 16S rRNA, 64% (24 residues) of which are methylated at O-2′ of ribose, and 8 modified species in 23S rRNA, 86% (43 residues) of which are ribose methylated, a form of modification shown in earlier studies to enhance stability of the polynucleotide chain. From cultures grown at progressively higher temperatures, 60, 75, and 83°C, a slight trend toward increased ribose methylation levels was observed, with greatest net changes over the 23°C range shown for 2′-O-methyladenosine in 16S rRNA (21% increase) and for 2′-O-methylcytidine (24%) and 2′-O-methylguanosine (22%) in 23S rRNA. These findings are discussed in terms of the potential role of modification in stabilization of rRNA in the thermal environment.