RocS drives chromosome segregation and nucleoid protection in Streptococcus pneumoniae


Chromosome segregation in bacteria is poorly understood outside some prominent model strains1,2,3,4,5 and even less is known about how it is coordinated with other cellular processes. This is the case for the opportunistic human pathogen Streptococcus pneumoniae (the pneumococcus)6, which lacks the Min and the nucleoid occlusion systems7, and possesses only an incomplete chromosome partitioning Par(A)BS system, in which ParA is absent8. The bacterial tyrosine kinase9 CpsD, which is required for capsule production, was previously found to interfere with chromosome segregation10. Here, we identify a protein of unknown function that interacts with CpsD and drives chromosome segregation. RocS (Regulator of Chromosome Segregation) is a membrane-bound protein that interacts with both DNA and the chromosome partitioning protein ParB to properly segregate the origin of replication region to new daughter cells. In addition, we show that RocS interacts with the cell division protein FtsZ and hinders cell division. Altogether, this work reveals that RocS is the cornerstone of a nucleoid protection system ensuring proper chromosome segregation and cell division in coordination with the biogenesis of the protective capsular layer.

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Fig. 1: Effect of rocS deletion on capsule production and nucleoid distribution.
Fig. 2: oriC segregation patterns in WT and ΔrocS cells.
Fig. 3: Localization of GFP-RocS and derivatives and the effect on nucleoid localization.
Fig. 4: Deletion of rocS in phospho-ablative and phospho-mimetic CpsD mutants and a model for the RocS nucleoid protection system.

Data availability

The data that support the findings of this study are available from the corresponding author on request. The ChIP-seq data were deposited at the NCBI Sequence Read Archive (accession number PRJNA511435) and Gene Expression Omnibus (accession number GSE129717).


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Work by the Grangeasse lab is supported by grants from the CNRS, the University of Lyon, the Agence National de la Recherche (ANR-10-BLAN-1303-01 and ANR-15-CE32-0001-01), the Region Auvergne-Rhône-Alpes (financial support for C.M. and P.S.G.), the ‘Fondation pour la Recherche Médicale’ (financial support for N.D. (ING20150532637) and C.M. (FDT20170437272)) and the Bettencourt-Schueller Foundation. Work by the Veening lab is supported by the Swiss National Science Foundation (project grant 31003A_172861), a JPIAMR grant (50-52900-98-202) from the Netherlands Organization for Health Research and Development (ZonMW) and the ERC consolidator grant 771534-PneumoCaTChER. We thank S. Ravaud for help in RocS structural predictions, A. Fenton (University of Sheffield, Sheffield, UK) for providing us with the D39∆cps strain and K. Weaver (University of South Dakota, Vermillion, SD, USA) for providing the pAD1 plasmid. We acknowledge the contribution of the Protein Science of the SFR Biosciences Gerland-Lyon Sud (UMS344/US8).

Author information

C.G. directed the study. C.M. conducted the cell imaging experiments and analyses with A.D., the genetic experiments with J.N., and the protein purification experiments and western blot analysis with J.-P.L., C.F. and S.N.N. C.M. and N.D. implemented the oriC localization system. J.-P.L. performed the microscale thermophoresis experiments. C.M. and J.S. performed the oriC/ter ratio and ChIP-seq experiments. M.-F.N.-G. performed the yeast two-hybrid experiments. P.S.G. performed the phylogeny analyses. All authors designed and analysed the data. C.G. and J.-W.V. wrote the manuscript and all authors edited the manuscript.

Correspondence to Christophe Grangeasse.

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Supplementary information


Nucleoid segregation in wild-type R800 cells.


Absence of chromosome segregation in ∆rocS cells.


Chromosome pinching in ∆rocS cells.


Localization of GFP-RocS.

Supplementary Information

Supplementary Figures 1–23, Supplementary Video legends, and Supplementary Tables 1 and 2.

Reporting Summary

Supplementary Video 1

Nucleoid segregation in wild-type R800 cells.

Supplementary Video 2

Absence of chromosome segregation in ∆rocS cells.

Supplementary Video 3

Chromosome pinching in ∆rocS cells.

Supplementary Video 4

Localization of GFP-RocS.

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Mercy, C., Ducret, A., Slager, J. et al. RocS drives chromosome segregation and nucleoid protection in Streptococcus pneumoniae. Nat Microbiol 4, 1661–1670 (2019).

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