Convergent evolution in two bacterial replicative helicase loaders.

Jillian Chase, James Berger, David Jeruzalmi

Trends in biochemical sciences 2022 Jul

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Dedicated loader proteins play essential roles in bacterial DNA replication by opening ring-shaped DnaB-family helicases and chaperoning single-stranded (ss)DNA into a central motor chamber as a prelude to DNA unwinding. Although unrelated in sequence, the Escherichia coli DnaC and bacteriophage λ P loaders feature a similar overall architecture: a globular domain linked to an extended lasso/grappling hook element, located at their N and C termini, respectively. Both loaders remodel a closed DnaB ring into nearly identical right-handed open conformations. The sole element shared by the loaders is a single alpha helix, which binds to the same site on the helicase. Physical features of the loaders establish that DnaC and λ P evolved independently to converge, through molecular mimicry, on a common helicase-opening mechanism. Copyright © 2022 Elsevier Ltd. All rights reserved.

Citation

Jillian Chase, James Berger, David Jeruzalmi. Convergent evolution in two bacterial replicative helicase loaders. Trends in biochemical sciences. 2022 Jul;47(7):620-630