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F‐actin‐like filaments formed by plasmid segregation protein ParM
Author(s) -
van den Ent Fusinita,
MøllerJensen Jakob,
Amos Linda A.,
Gerdes Kenn,
Löwe Jan
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf672
Subject(s) - mreb , biology , cytoskeleton , actin , plasmid , microbiology and biotechnology , intermediate filament , protein filament , dna , biophysics , biochemistry , cell
It was the general belief that DNA partitioning in prokaryotes is independent of a cytoskeletal structure, which in eukaryotic cells is indispensable for DNA segregation. Recently, however, immunofluorescence microscopy revealed highly dynamic, filamentous structures along the longitudinal axis of Escherichia coli formed by ParM, a plasmid‐encoded protein required for accurate segregation of low‐copy‐number plasmid R1. We show here that ParM polymerizes into double helical protofilaments with a longitudinal repeat similar to filamentous actin (F‐actin) and MreB filaments that maintain the cell shape of non‐spherical bacteria. The crystal structure of ParM with and without ADP demonstrates that it is a member of the actin family of proteins and shows a domain movement of 25° upon nucleotide binding. Furthermore, the crystal structure of ParM reveals major differences in the protofilament interface compared with F‐actin, despite the similar arrangement of the subunits within the filaments. Thus, there is now evidence for cytoskeletal structures, formed by actin‐like filaments that are involved in plasmid partitioning in E.coli .