%0 Journal Article %1 Piedrafita2010Simple %A Piedrafita, Gabriel %A Montero, Francisco %A Morán, Federico %A Cárdenas, Mar\'ıa L. %A Cornish-Bowden, Athel %D 2010 %I Public Library of Science %J PLoS Comput Biol %K metabolism robustness %N 8 %P e1000872+ %R 10.1371/journal.pcbi.1000872 %T A Simple Self-Maintaining Metabolic System: Robustness, Autocatalysis, Bistability %U http://dx.doi.org/10.1371/journal.pcbi.1000872 %V 6 %X A living organism must not only organize itself from within; it must also maintain its organization in the face of changes in its environment and degradation of its components. We show here that a simple (M,R)-system consisting of three interlocking catalytic cycles, with every catalyst produced by the system itself, can both establish a non-trivial steady state and maintain this despite continuous loss of the catalysts by irreversible degradation. As long as at least one catalyst is present at a sufficient concentration in the initial state, the others can be produced and maintained. The system shows bistability, because if the amount of catalyst in the initial state is insufficient to reach the non-trivial steady state the system collapses to a trivial steady state in which all fluxes are zero. It is also robust, because if one catalyst is catastrophically lost when the system is in steady state it can recreate the same state. There are three elementary flux modes, but none of them is an enzyme-maintaining mode, the entire network being necessary to maintain the two catalysts. The question of whether a whole organism (as opposed to particular properties of an organism) can be modeled in the computer has been controversial. As a step towards resolving it, we have studied the feasibility of simulating the behavior of a simple theoretical model in which all the catalysts needed for the metabolism of a system are themselves products of the metabolism itself, and in which there is a continuous loss of catalysts in unavoidable degradation reactions. In addition to a trivial ( ” dead”) steady state in which all rates are zero, the model is capable of establishing a stable non-trivial steady state with finite and reproducible fluxes. This can be achieved by ” seeding” it with a sufficient quantity of at least one of the catalysts needed for functioning. It is also robust, because it can recover from a catastrophic disappearance of a catalyst.

@article{Piedrafita2010Simple, abstract = {A living organism must not only organize itself from within; it must also maintain its organization in the face of changes in its environment and degradation of its components. We show here that a simple ({M,R})-system consisting of three interlocking catalytic cycles, with every catalyst produced by the system itself, can both establish a non-trivial steady state and maintain this despite continuous loss of the catalysts by irreversible degradation. As long as at least one catalyst is present at a sufficient concentration in the initial state, the others can be produced and maintained. The system shows bistability, because if the amount of catalyst in the initial state is insufficient to reach the non-trivial steady state the system collapses to a trivial steady state in which all fluxes are zero. It is also robust, because if one catalyst is catastrophically lost when the system is in steady state it can recreate the same state. There are three elementary flux modes, but none of them is an enzyme-maintaining mode, the entire network being necessary to maintain the two catalysts. The question of whether a whole organism (as opposed to particular properties of an organism) can be modeled in the computer has been controversial. As a step towards resolving it, we have studied the feasibility of simulating the behavior of a simple theoretical model in which all the catalysts needed for the metabolism of a system are themselves products of the metabolism itself, and in which there is a continuous loss of catalysts in unavoidable degradation reactions. In addition to a trivial ( ” dead”) steady state in which all rates are zero, the model is capable of establishing a stable non-trivial steady state with finite and reproducible fluxes. This can be achieved by ” seeding” it with a sufficient quantity of at least one of the catalysts needed for functioning. It is also robust, because it can recover from a catastrophic disappearance of a catalyst.}, added-at = {2018-12-02T16:09:07.000+0100}, author = {Piedrafita, Gabriel and Montero, Francisco and Mor\'{a}n, Federico and C\'{a}rdenas, Mar\'{\i}a L. and Cornish-Bowden, Athel}, biburl = {https://www.bibsonomy.org/bibtex/272396ecb9d546924c68bcf360e594822/karthikraman}, citeulike-article-id = {7577548}, citeulike-linkout-0 = {http://dx.doi.org/10.1371/journal.pcbi.1000872}, day = 5, doi = {10.1371/journal.pcbi.1000872}, interhash = {0ddfb6f328a434f513534dbcb0c04766}, intrahash = {72396ecb9d546924c68bcf360e594822}, journal = {PLoS Comput Biol}, keywords = {metabolism robustness}, month = aug, number = 8, pages = {e1000872+}, posted-at = {2010-08-09 09:46:42}, priority = {2}, publisher = {Public Library of Science}, timestamp = {2018-12-02T16:09:07.000+0100}, title = {A Simple {Self-Maintaining} Metabolic System: Robustness, Autocatalysis, Bistability}, url = {http://dx.doi.org/10.1371/journal.pcbi.1000872}, volume = 6, year = 2010 }