Laboratory of Molecular Biology

About: Laboratory of Molecular Biology is a facility organization based out in Cambridge, Cambridgeshire, United Kingdom. It is known for research contribution in the topics: Gene & RNA. The organization has 19395 authors who have published 24236 publications receiving 2101480 citations.

Gene regulatory network growth by duplication

Abstract: We are beginning to elucidate transcriptional regulatory networks on a large scale1 and to understand some of the structural principles of these networks2,3, but the evolutionary mechanisms that form these networks are still mostly unknown. Here we investigate the role of gene duplication in network evolution. Gene duplication is the driving force for creating new genes in genomes: at least 50% of prokaryotic genes4,5 and over 90% of eukaryotic genes6 are products of gene duplication. The transcriptional interactions in regulatory networks consist of multiple components, and duplication processes that generate new interactions would need to be more complex. We define possible duplication scenarios and show that they formed the regulatory networks of the prokaryote Escherichia coli and the eukaryote Saccharomyces cerevisiae. Gene duplication has had a key role in network evolution: more than one-third of known regulatory interactions were inherited from the ancestral transcription factor or target gene after duplication, and roughly one-half of the interactions were gained during divergence after duplication. In addition, we conclude that evolution has been incremental, rather than making entire regulatory circuits or motifs by duplication with inheritance of interactions.

Directed evolution of polymerase function by compartmentalized self-replication

Abstract: We describe compartmentalized self-replication (CSR), a strategy for the directed evolution of enzymes, especially polymerases. CSR is based on a simple feedback loop consisting of a polymerase that replicates only its own encoding gene. Compartmentalization serves to isolate individual self-replication reactions from each other. In such a system, adaptive gains directly (and proportionally) translate into genetic amplification of the encoding gene. CSR has applications in the evolution of polymerases with novel and useful properties. By using three cycles of CSR, we obtained variants of Taq DNA polymerase with 11-fold higher thermostability than the wild-type enzyme or with a >130-fold increased resistance to the potent inhibitor heparin. Insertion of an extra stage into the CSR cycle before the polymerase reaction allows its application to enzymes other than polymerases. We show that nucleoside diphosphate kinase and Taq polymerase can form such a cooperative CSR cycle based on reciprocal catalysis, whereby nucleoside diphosphate kinase produces the substrates required for the replication of its own gene. We also find that in CSR the polymerase genes themselves evolve toward more efficient replication. Thus, polymerase genes and their encoded polypeptides cooperate to maximize postselection copy number. CSR should prove useful for the directed evolution of enzymes, particularly DNA or RNA polymerases, as well as for the design and study of in vitro self-replicating systems mimicking prebiotic evolution and viral replication.