Multiprotein E. coli SSB-ssDNA complex shows both stable binding and rapid dissociation due to interprotein interactions.

ABSTRACT: Escherichia coli SSB (EcSSB) is a model single-stranded DNA (ssDNA) binding protein critical in genome maintenance. EcSSB forms homotetramers that wrap ssDNA in multiple conformations to facilitate DNA replication and repair. Here we measure the binding and wrapping of many EcSSB proteins to a single long ssDNA substrate held at fixed tensions. We show EcSSB binds in a biphasic manner, where initial wrapping events are followed by unwrapping events as ssDNA-bound protein density passes critical saturation and high free protein concentration increases the fraction of EcSSBs in less-wrapped conformations. By destabilizing EcSSB wrapping through increased substrate tension, decreased substrate length, and protein mutation, we also directly observe an unstable bound but unwrapped state in whic

SUBMITTER: Naufer MN 

PROVIDER: S-EPMC7897507 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature