Quote:
|
Abstract: DNA has been extensively scrutinized for its feasibility as parts in nanotechnology, but another natural building block, RNA, has been largely ignored.
|
As far as OOL is concerned, RNA (ribonucleic acid) is less stable that DNA (deoxyribonucleic acid). RNA has a reactive hydroxyl group (-OH) on C2’ while DNA has only a hydrogen atom (hence, the 2’ carbon of DNA has been “deoxy’d”, making it
deoxyribonucleic acid). As one example, RNA is not stable in alkaline conditions that DNA is quite “comfortable” in. So even if RNA does turn out to better than DNA in nanotechnology, that doesn’t necessarily – and most likely doesn’t - carry over into OOL.
Quote:
|
Abstract: RNA can be manipulated to form versatile shapes, thus providing an element of adaptability to DNA nanotechnology, which is predominantly based upon a double-helical structure.
|
Yes, cellular DNA is rather a bland character as far as conformation is concerned: it exists as a double helix consisting of two anti-parallel polynucleotide chains that spiral around a common axis. There is very little conformational variation (DNA in cells is typically a right-handed double helix, called the B form. Sometimes other forms – such as A or even Z – can exist in cells, but even then, there really isn’t too much range of shape for cellular DNA. If one adds DNA-binding proteins, then the DNA double helix can be bent and otherwise “distorted”, but that requires proteins in addition to DNA).
Cellular RNA, on the other hand, comes in several shapes. mRNA is basically a single-stranded, linear polyribonucleotide; tRNA adopts an L shape (a “clover leaf” when considering only a two-dimensional view); and rRNA adopts a kind of globular 3-D shape…something like. RNA can forms loops, stem-loops, pseudoknots, and other complex shapes – these can lead to catalytic capabilities. Catalytic RNAs are called ribozymes (but technically, not all ribozyme are catalysts).
So even in cells one can see a fairly wide range of shapes and functions for RNA, including catalytic abilities. Now, since RNA can carry genetic information, and, can also perform catalytic functions, OOL researchers figure it’s the perfect solution to the chicken-or-egg paradox associated with the origin of the interrelated and interdependent associations between DNA, RNA, and proteins in extant cells.
So RNA is definitely a good target for OOL research, whether this article has anything to say on the matter or not.
Quote:
|
Abstract: The DNA-packaging motor of bacterial virus phi29 contains six DNA-packaging pRNAs (pRNA), which together form a hexameric ring via loop/loop interaction. Here we report that this pRNA can be redesigned to form a variety of structures and shapes, including twins, tetramers, rods, triangles, and arrays several microns in size via interaction of programmed helical regions and loops. RNA array formation required a defined nucleotide number for twisting of the interactive helix and a palindromic sequence.
|
Maybe that’s relevant…maybe it’s not. Without these “triangles” and other shapes, RNA has been shown capable of partial replicase activity. I have little to no doubt that RNA molecules can be created that can replicate themselves – the question is, how likely is it that those replicases could arise spontaneously? As an analogy, we know that silicon and other elements can be made into a Pentium 4 CPU, but we don’t expect that such would occur spontaneously.
Quote:
|
Abstract: Such arrays are unusually stable and resistant to a wide range of temperatures, salt concentrations, and pH.
|
Which might be a negative in regards to OOL: depends on exactly what they mean. For example, if the RNA arrays are unusually stable because they are very rigid, then their catalytic capabilities would likely be reduced relative to more flexible molecules
