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

ABSTRACT: Correct chromosomal segregation, coordinated with cell division, is crucial for bacterial survival, but despite extensive studies, the mechanisms underlying this remain incompletely understood in mycobacteria. We report a detailed investigation of the dynamic interactions between ParA and ParB partitioning proteins in Mycobacterium smegmatis using microfluidics and time-lapse fluorescence microscopy to observe both proteins simultaneously. During growth and division, ParB presents as a focused fluorescent spot that subsequently splits in two. One focus moves towards a higher concentration of ParA at the new pole, while the other moves towards the old pole. We show ParB movement is in part an active process that does not rely on passive movement associated with cell growth. In some cells, another round of ParB segregation starts before cell division is complete, consistent with initiation of a second round of chromosome replication. ParA fluorescence distribution correlates with cell size, and in sister cells, the larger cell inherits a local peak of concentrated ParA, while the smaller sister inherits more homogeneously distributed protein. Cells which inherit more ParA grow faster than their sister cell, raising the question of whether inheritance of a local concentration of ParA provides a growth advantage. Alterations in levels of ParA and ParB were also found to disturb cell growth.

SUBMITTER: Uhia I

PROVIDER: S-EPMC6007833 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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

Uhía Iria I Priestman Miles M Joyce Graham G Krishnan Nitya N Shahrezaei Vahid V Robertson Brian D BD

PloS one 20180619 6

Correct chromosomal segregation, coordinated with cell division, is crucial for bacterial survival, but despite extensive studies, the mechanisms underlying this remain incompletely understood in mycobacteria. We report a detailed investigation of the dynamic interactions between ParA and ParB partitioning proteins in Mycobacterium smegmatis using microfluidics and time-lapse fluorescence microscopy to observe both proteins simultaneously. During growth and division, ParB presents as a focused f ...[more]

PMID: 29920558

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Project description:Representatives of two families of bacterial Par proteins, ParA and ParB, are encoded by the majority of bacterial chromosomes in the close vicinity of oriC. ParA(Soj) and ParB(Spo0J) proteins of Pseudomonas aeruginosa are both important for optimal growth, nucleoids segregation, cell division and different types of motility. Comparative transcriptome analysis of parAnull, parBnull mutants versus parental PAO1161 strain of P. aeruginosa demonstrated global changes in genes expression pattern in logarithmic phase of planktonic cultures grown on rich medium. The set of genes that were similarly regulated in both mutant strains as compared to the wild-type strain as well as two sets of genes uniquely affected in the particular mutant were defined suggesting that ParA and ParB may act in common and independently. In general, many genes involved in cell division, DNA and RNA processing and metabolic processes were down-regulated in mutant cells, in contrast genes which products play a role in adaptation, protection, motility, cell-to-cell signaling as well as signal transduction increased their expression in par mutant cells. Besides their role in chromosome segregation, ParA and ParB seem to have the potential to regulate genes transcription. The altered expression of a large number of genes encoding known or predicted transcriptional regulators and genes coding for products involved in c-di-GMP signalling, suggests that the part of observed global changes in genes expression pattern in parAnull and parBnull mutants might be the effect of indirect regulation mediated by regulatory genes under ParA and ParB control. The extended regulatory network provides the mechanism to modulate genes expression in response to the stage of the chromosome segregation process and cell cycle. Pseudomonas aeruginosa PAO1161 (leu, r-, RifR), derivative of PAO1, as a control (reference) strain, Pseudomonas aeruginosa PAO1161 parA1-40::smh (parAnull) and Pseudomonas aeruginosa PAO1161 parB1-18::TcR (parBnull) disruption mutant strains were used in the experiments. Three independent biological replicates of total RNA were isolated for each strain from logarithmic (Log) phase of planktonic culture grown on rich medium (L broth) at 37oC. In total, nine samples of RNA were prepared.

Dataset Information

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

Publications

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

Similar Datasets

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