A direct proofreader–clamp interaction stabilizes the Pol III replicase in the polymerization mode

Processive DNA synthesis by the αεθ core of the Escherichia coli Pol III replicase requires it to be bound to the β₂ clamp via a site in the α polymerase subunit. How the ε proofreading exonuclease subunit influences DNA synthesis by α was not previously understood. In this work, bulk assays of DNA replication were used to uncover a non‐proofreading activity of ε. Combination of mutagenesis with biophysical studies and single‐molecule leading‐strand replication assays traced this activity to a novel β‐binding site in ε that, in conjunction with the site in α, maintains a closed state of the αεθ–β₂ replicase in the polymerization mode of DNA synthesis. The ε–β interaction, selected during evolution to be weak and thus suited for transient disruption to enable access of alternate polymerases and other clamp binding proteins, therefore makes an important contribution to the network of protein–protein interactions that finely tune stability of the replicase on the DNA template in its various conformational states.     

Publication date and author spelling for the hidden angelshark Squatina occulta

Two dates of publication have been associated with the hidden angelshark Squatina occulta. Additionally, the name of the second author of this species has been cited with different spellings in different publications. Both inconsistencies are addressed in this study. It is suggested that the hidden angelshark be consistently cited as Squatina occulta Vooren & da Silva 1991.