Cellular Mechanics and Biophysics by Claudia Tanja Mierke

Author:Claudia Tanja Mierke
Language: eng
Format: epub
ISBN: 9783030585327
Publisher: Springer International Publishing

11.10.2 Genetic Code of Mitochondria

The primary reason that resulted in the mathematical framework of the euplotid nuclear code was to identify informational failure recognition/correction mechanisms. In fact, the main ingredients of error recognition/correction codes have been identified. For example, there are links among dichotomous classes, orthogonal arrays and finite groups. Additionally, the redundancy/degeneracy is connected to separate symmetry groups. Can at least the hypothetical mechanisms of failure recognition and correction be solved? The task is a rather complicated one, however, when these mechanisms are generally grounded in genetic codes, each with its own degeneration, it is obvious to concentrate on the simplest life system that has a genetic code: the mitochondrion. The genetic code of the mitochondrion represents the simplest and most symmetrical of all code versions and was suggested as a model for the early code (Jukes 1983; Ohama et al. 2008), the precursor of the universal genetic code of LUCA.

The mitochondrial genetic code of vertebrates varies in only four codons from the standard nuclear genetic code. The degeneration pattern of the mitochondrial code is far simpler and more symmetrical. In this context, the amino acids suffer from either degeneration 2 or 4. Noteworthy, it is feasible to demonstrate that there is also a unique non-power representation scheme for the mitochondrial code that precisely defines its degeneration pattern. The setting is governed by the six non-power weights (8, 8, 4, 2, 1, 0). In Table 11.6, the non-power denominations for the two genetic codes are given. In specific, the simplification of the degeneration pattern of the mitochondrial code is linked to the existence of a 0-weight, which in other words means that there are no elements with degeneration 1. As the weight 0 is not included in the additive degradation of a number, it has the consequence of double labeling. This means that the presentation is split into two identical parts. That fact has far-reaching implications in the characterization of the linked degeneration and guided toward a biological hypothesis on the origin of degeneration in the coding of proteins (Gonzalez et al. 2012).

In a similar way to the mathematical hypothesis, the biological hypothesis is founded on symmetry characteristics. Symmetry provides the key feature for linking the mathematical modeling with the chemical and biological characteristics of the genetic code. In short, the major finding suggests that the degeneration pattern of the vertebrate mitochondrial genetic code can be accurately characterized by primordial tRNA adapters operating on a specific batch of four-base codons, which are referred to as tesserae. These adapters offer both inverse and self-complementary symmetries. These symmetries involve the invariance of the Hamiltonian interaction in relation to those spatial transformations. An interesting hypothesis that needs to be explored is that conserved quantities associated with these symmetries may have evolutionarily influenced the shape of today’s codes. The tessera set is provided in Table 11.1.

The results of this research on the mitochondrial genetic code have significant consequences for the investigation of the genetic code of the mitochondria: firstly the molecular evolution and

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