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Selection for replicases in protocells.

Bianconi G, Zhao K, Chen IA, Nowak MA - PLoS Comput. Biol. (2013)

Bottom Line: In a well-mixed medium, natural selection would not favor such replicases because their presence equally benefits sequences with or without replicase activity.Here we show that protocells can select for replicases.We calculate the error threshold that is compatible with selecting for replicases.

View Article: PubMed Central - PubMed

Affiliation: School of Mathematical Sciences, Queen Mary University of London, London, United Kingdom.

ABSTRACT
We consider a world of nucleotide sequences and protocells. The sequences have the property of spontaneous self-replication. Some sequences - so-called replicases - have enzymatic activity in the sense of enhancing the replication rate of all (or almost all) sequences. In a well-mixed medium, natural selection would not favor such replicases because their presence equally benefits sequences with or without replicase activity. Here we show that protocells can select for replicases. We assume that sequences replicate within protocells and that protocells undergo spontaneous division. This leads to particular population structures which can augment the abundance of replicases. We explore various assumptions regarding replicase activity and protocell division. We calculate the error threshold that is compatible with selecting for replicases.

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Reaction kinetics for protocells of different composition for the four replicases considered in this paper.The sequences of type A indicate the replicases. All sequences undergo spontaneous self-replication and are targets of replicase activity. The sequences of type B, in absence of sequences of type A in the protocell, replicate at rate 1. A type A sequence replicates with mutation with probability , and the offspring will be a type B sequence. If the sequences  encode the replicase , it is sufficient that at least one sequence of type A is present in the protocell for enhancing the replication of every sequence in the same protocell to . If the sequences  encode for the replicase , the sequences enhance the rate of replication of all the other sequences to . If the sequences  encode the replicase , and there are A sequences in the protocell, the rate of all the sequences is given by  with . If the sequences  encode the replicase , and there are A sequences in the protocell, the rate of the A sequences is given by  while the rate of replication of the B sequences is  with α>0.
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pcbi-1003051-g002: Reaction kinetics for protocells of different composition for the four replicases considered in this paper.The sequences of type A indicate the replicases. All sequences undergo spontaneous self-replication and are targets of replicase activity. The sequences of type B, in absence of sequences of type A in the protocell, replicate at rate 1. A type A sequence replicates with mutation with probability , and the offspring will be a type B sequence. If the sequences encode the replicase , it is sufficient that at least one sequence of type A is present in the protocell for enhancing the replication of every sequence in the same protocell to . If the sequences encode for the replicase , the sequences enhance the rate of replication of all the other sequences to . If the sequences encode the replicase , and there are A sequences in the protocell, the rate of all the sequences is given by with . If the sequences encode the replicase , and there are A sequences in the protocell, the rate of the A sequences is given by while the rate of replication of the B sequences is with α>0.

Mentions: In Figure 2 we show the reaction kinetics for all four types of replicases.


Selection for replicases in protocells.

Bianconi G, Zhao K, Chen IA, Nowak MA - PLoS Comput. Biol. (2013)

Reaction kinetics for protocells of different composition for the four replicases considered in this paper.The sequences of type A indicate the replicases. All sequences undergo spontaneous self-replication and are targets of replicase activity. The sequences of type B, in absence of sequences of type A in the protocell, replicate at rate 1. A type A sequence replicates with mutation with probability , and the offspring will be a type B sequence. If the sequences  encode the replicase , it is sufficient that at least one sequence of type A is present in the protocell for enhancing the replication of every sequence in the same protocell to . If the sequences  encode for the replicase , the sequences enhance the rate of replication of all the other sequences to . If the sequences  encode the replicase , and there are A sequences in the protocell, the rate of all the sequences is given by  with . If the sequences  encode the replicase , and there are A sequences in the protocell, the rate of the A sequences is given by  while the rate of replication of the B sequences is  with α>0.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3649988&req=5

pcbi-1003051-g002: Reaction kinetics for protocells of different composition for the four replicases considered in this paper.The sequences of type A indicate the replicases. All sequences undergo spontaneous self-replication and are targets of replicase activity. The sequences of type B, in absence of sequences of type A in the protocell, replicate at rate 1. A type A sequence replicates with mutation with probability , and the offspring will be a type B sequence. If the sequences encode the replicase , it is sufficient that at least one sequence of type A is present in the protocell for enhancing the replication of every sequence in the same protocell to . If the sequences encode for the replicase , the sequences enhance the rate of replication of all the other sequences to . If the sequences encode the replicase , and there are A sequences in the protocell, the rate of all the sequences is given by with . If the sequences encode the replicase , and there are A sequences in the protocell, the rate of the A sequences is given by while the rate of replication of the B sequences is with α>0.
Mentions: In Figure 2 we show the reaction kinetics for all four types of replicases.

Bottom Line: In a well-mixed medium, natural selection would not favor such replicases because their presence equally benefits sequences with or without replicase activity.Here we show that protocells can select for replicases.We calculate the error threshold that is compatible with selecting for replicases.

View Article: PubMed Central - PubMed

Affiliation: School of Mathematical Sciences, Queen Mary University of London, London, United Kingdom.

ABSTRACT
We consider a world of nucleotide sequences and protocells. The sequences have the property of spontaneous self-replication. Some sequences - so-called replicases - have enzymatic activity in the sense of enhancing the replication rate of all (or almost all) sequences. In a well-mixed medium, natural selection would not favor such replicases because their presence equally benefits sequences with or without replicase activity. Here we show that protocells can select for replicases. We assume that sequences replicate within protocells and that protocells undergo spontaneous division. This leads to particular population structures which can augment the abundance of replicases. We explore various assumptions regarding replicase activity and protocell division. We calculate the error threshold that is compatible with selecting for replicases.

Show MeSH
Related in: MedlinePlus