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Analysis of ParAB dynamics in mycobacteria shows active movement of ParB and differential inheritance of ParA

Iria Uhía1, Miles Priestman1, Graham Joyce1

  • 1MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College London, London, United Kingdom.

Plos One
|June 20, 2018
PubMed

Insights

Bacterial chromosome segregation relies on ParA and ParB proteins. This study reveals ParB actively moves to cell poles, and ParA concentration may influence cell growth post-division in mycobacteria.

Area of Science:

  • Microbiology
  • Cell Biology
  • Molecular Biology

Background:

  • Accurate chromosomal segregation is vital for bacterial survival and reproduction.
  • The precise mechanisms of chromosome partitioning in mycobacteria are not fully understood.
  • ParA and ParB are key proteins involved in bacterial DNA segregation.

Purpose of the Study:

  • To investigate the dynamic interactions between ParA and ParB partitioning proteins in Mycobacterium smegmatis.
  • To elucidate the mechanisms of chromosomal segregation in mycobacteria.
  • To explore the role of ParA and ParB in cell division and growth.

Main Methods:

  • Utilized microfluidics and time-lapse fluorescence microscopy to simultaneously observe ParA and ParB dynamics.
  • Tracked the movement and distribution of ParA and ParB proteins during cell growth and division.
  • Quantified ParA and ParB fluorescence intensity and localization in relation to cell morphology.

Main Results:

  • Observed ParB forming a focused spot that splits and moves actively towards cell poles.
  • Demonstrated that ParB segregation can initiate before cell division is complete, suggesting early chromosome replication.
  • Found ParA distribution correlates with cell size, with larger cells inheriting a concentrated ParA peak, leading to faster growth.

Conclusions:

  • ParB segregation is an active process in Mycobacterium smegmatis, not solely dependent on cell growth.
  • Differential inheritance of ParA may confer a growth advantage to daughter cells.
  • Aberrant levels of ParA and ParB disrupt normal cell growth, highlighting their critical roles.

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