Accessory factors promote AlfA-dependent plasmid segregation by regulating filament nucleation, disassembly, and bundling.

نویسندگان

  • Jessica K Polka
  • Justin M Kollman
  • R Dyche Mullins
چکیده

In bacteria, some plasmids are partitioned to daughter cells by assembly of actin-like proteins (ALPs). The best understood ALP, ParM, has a core set of biochemical properties that contributes to its function, including dynamic instability, spontaneous nucleation, and bidirectional elongation. AlfA, an ALP that pushes plasmids apart in Bacillus, relies on a different set of underlying properties to segregate DNA. AlfA elongates unidirectionally and is not dynamically unstable; its assembly and disassembly are regulated by a cofactor, AlfB. Free AlfB breaks up AlfA bundles and promotes filament turnover. However, when AlfB is bound to the centromeric DNA sequence, parN, it forms a segrosome complex that nucleates and stabilizes AlfA filaments. When reconstituted in vitro, this system creates polarized, motile comet tails that associate by antiparallel filament bundling to form bipolar, DNA-segregating spindles.

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عنوان ژورنال:
  • Proceedings of the National Academy of Sciences of the United States of America

دوره 111 6  شماره 

صفحات  -

تاریخ انتشار 2014