VADIM A. RATNER
ratner@bionet.nsc.ru
Annotation
Macromolecular universal SYstems of SElf-Reproduction (sysers) exemplify the kernel structures of Molecular Genetic Regulatory Systems organization. The types of macromolecular assemblies variously composed are being considered. Moreover, an ability of such an assembly to be the kernel of a system’s stable organization is estimated. The following criteria were evaluated: а) template synthesis of macromolecules; b) catalysis of molecular processes; c) the presence of a syser as a “kernel” of molecular genetic organization; d) upper boundaries restricting the size of coding macromolecules and limiting the “catastrophes” of mutational and other losses; e) requirements for dynamical, structural, and evolutionary stability. It was shown that (i) ribozyme-replicase may be the basis for an RNA-assembly organization for a short time period and under condition that the length of RNA fraction does not exceed that of a gene; (ii) syser RNA-protein may be the basis of organization of an assembly with the overall length up to RNA-virus genome; (iii) syser DNA-RNA-protein may serve as a basis of cellular organization with the huge reserves of evolutionary scenarios.
Coding macromolecules, assemblies of macromolecules, MGRS. Block-modular principle of organization1-3.
Coding macromolecules (DNA, RNA, Proteins): their main molecular properties and functions are determined almost exclusively by the size, content, and order of monomers. The unit of their description is represented by a fraction.
Assemby of macromolecules: a set of fractions, interrelated between each other by the processes of template- and non-template synthesis, enzyme catalysis, mutual recognition and aggregation, degradation, alteration, structural linkage, etc. and subjected into a media, where such processes may take place (i.e., “informational box” according to M. Eigen).
Molecular-genetic regulatory system (MGRS) of a cell: a set of coding macromolecules (fractions of DNA, RNA, proteins, and their complexes), including molecular enzyme complexes that accomplish with them different molecular processes (i.e., serve as executive machines): synthesis, degradation, transport, repair, recombination, modification, regulation, etc.
Dynamic structure of an assembly and MGRS is given by the set of concentrations of the fractions and complexes, together with their construction, which is the scheme of functional interactions between them. At present, these schemes are called gene networks.
Assemblies of macromolecules and, especially, MGRS are organized by block-modular principle. A block (module) is an autonomous by structure, holistic subsystem with a definite functional loading. Each module type has a lower level of complexity that is necessary for supporting its function. Besides, there exists an upper limit of a module type complexity that provides a sufficient variability in functions and combinatorial variability. Additionally, each particular module type has an upper limit of functional loading.