Structural basis for DNA processing and membrane translocation by ComEC in natural transformation
Summary
Natural transformation is one of the major pathways of horizontal gene transfer in bacteria, enabling the acquisition of extracellular DNA and its integration into the host genome. ComEC is a membrane protein responsible for DNA translocation in this process, yet its precise function and structure have remained elusive. Here, we report cryo-electron microscopy structures of ComEC in DNA-free, single-stranded DNA (ssDNA)-bound, and double-stranded DNA (dsDNA)-bound forms, together with bioc
Content
# Structural basis for DNA processing and membrane translocation by ComEC in natural transformation
*Published: 2026 Apr 16*
Natural transformation is one of the major pathways of horizontal gene transfer
in bacteria, enabling the acquisition of extracellular DNA and its integration
into the host genome. ComEC is a membrane protein responsible for DNA
translocation in this process, yet its precise function and structure have
remained elusive. Here, we report cryo-electron microscopy structures of ComEC
in DNA-free, single-stranded DNA (ssDNA)-bound, and double-stranded DNA
(dsDNA)-bound forms, together with biochemical analyses. These structures reveal
that ComEC cleaves one strand of dsDNA at its extracellular domain and guides
the remaining strand into a positively charged pore formed within the membrane
domain. These findings provide a structural basis for the long-hypothesized
roles of ComEC in both DNA processing and translocation across the inner
membrane during natural transformation.
DOI: 10.1126/science.aea3485