Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Human cytomegalovirus overcomes SAMHD1 restriction in macrophages via pUL97

Abstract

The host restriction factor sterile alpha motif and histidine–aspartate domain-containing protein 1 (SAMHD1) is an important component of the innate immune system. By regulating the intracellular nucleotide pool, SAMHD1 influences cell division and restricts the replication of viruses that depend on high nucleotide concentrations. Human cytomegalovirus (HCMV) is a pathogenic virus with a tropism for non-dividing myeloid cells, in which SAMHD1 is catalytically active. Here we investigate how HCMV achieves efficient propagation in these cells despite the SAMHD1-mediated dNTP depletion. Our analysis reveals that SAMHD1 has the capability to suppress HCMV replication. However, HCMV has evolved potent countermeasures to circumvent this block. HCMV interferes with SAMHD1 steady-state expression and actively induces SAMHD1 phosphorylation using the viral kinase pUL97 and by hijacking cellular kinases. These actions convert SAMHD1 to its inactive phosphorylated form. This mechanism of SAMHD1 inactivation by phosphorylation might also be used by other viruses to overcome intrinsic immunity.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: SAMHD1 restricts HCMV replication in MDMs.
Fig. 2: SAMHD1 steady-state expression is reduced in HCMV-infected MDMs.
Fig. 3: HCMV interferes with SAMHD1 in an IFN-independent manner.
Fig. 4: HCMV-infected MDMs show elevated p-SAMHD1 T592.
Fig. 5: SAMHD1 T592 phosphorylation is induced by HCMV and mediated by CDKs.
Fig. 6: The HCMV-encoded kinase pUL97 phosphorylates SAMHD1.

Similar content being viewed by others

Data availability

All data generated and analysed during this study are included in this published manuscript. Further datasets supporting this study are available from the corresponding author upon request.

References

  1. Landolfo, S., De Andrea, M., Dell’Oste, V. & Gugliesi, F. Intrinsic host restriction factors of human cytomegalovirus replication and mechanisms of viral escape. World J. Virol. 5, 87–96 (2016).

    PubMed  PubMed Central  Google Scholar 

  2. Ahn, J. H. & Hayward, G. S. Disruption of PML-associated nuclear bodies by IE1 correlates with efficient early stages of viral gene expression and DNA replication in human cytomegalovirus infection. Virology 274, 39–55 (2000).

    CAS  PubMed  Google Scholar 

  3. Adler, M., Tavalai, N., Muller, R. & Stamminger, T. Human cytomegalovirus immediate–early gene expression is restricted by the nuclear domain 10 component Sp100. J. Gen. Virol. 92, 1532–1538 (2011).

    CAS  PubMed  Google Scholar 

  4. Wagenknecht, N. et al. Contribution of the major ND10 proteins PML, hDaxx and Sp100 to the regulation of human cytomegalovirus latency and lytic replication in the monocytic cell line THP-1. Viruses 7, 2884–2907 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  5. Gariano, G. R. et al. The intracellular DNA sensor IFI16 gene acts as restriction factor for human cytomegalovirus replication. PLoS Pathog. 8, e1002498 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Biolatti, M. et al. Regulatory interaction between the cellular restriction factor IFI16 and Viral pp65 (pUL83) modulates viral gene expression and IFI16 protein stability. J. Virol. 90, 8238–8250 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Dell’Oste, V. et al. Innate nuclear sensor IFI16 translocates into the cytoplasm during the early stage of in vitro human cytomegalovirus infection and is entrapped in the egressing virions during the late stage. J. Virol. 88, 6970–6982 (2014).

    PubMed  PubMed Central  Google Scholar 

  8. Goldstone, D. C. et al. HIV-1 restriction factor SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase. Nature 480, 379–382 (2011).

    CAS  PubMed  Google Scholar 

  9. Hollenbaugh, J. A. et al. dNTP pool modulation dynamics by SAMHD1 protein in monocyte-derived macrophages. Retrovirology 11, 63 (2014).

    PubMed  PubMed Central  Google Scholar 

  10. Powell, R. D., Holland, P. J., Hollis, T. & Perrino, F. W. Aicardi–Goutieres syndrome gene and HIV-1 restriction factor SAMHD1 is a dGTP-regulated deoxynucleotide triphosphohydrolase. J. Biol. Chem. 286, 43596–43600 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  11. Pauls, E. et al. Cell cycle control and HIV-1 susceptibility are linked by CDK6-dependent CDK2 phosphorylation of SAMHD1 in myeloid and lymphoid cells. J. Immunol. 193, 1988–1997 (2014).

    Google Scholar 

  12. St Gelais, C. et al. Identification of cellular proteins interacting with the retroviral restriction factor SAMHD1. J. Virol. 88, 5834–5844 (2014).

    Google Scholar 

  13. Yan, J. et al. CyclinA2–cyclin-dependent kinase regulates SAMHD1 protein phosphohydrolase domain. J. Biol. Chem. 290, 13279–13292 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  14. Cribier, A., Descours, B., Valadao, A. L., Laguette, N. & Benkirane, M. Phosphorylation of SAMHD1 by cyclin A2/CDK1 regulates its restriction activity toward HIV-1. Cell Rep. 3, 1036–1043 (2013).

    CAS  PubMed  Google Scholar 

  15. Hrecka, K. et al. Vpx relieves inhibition of HIV-1 infection of macrophages mediated by the SAMHD1 protein. Nature 474, 658–661 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. Laguette, N. et al. SAMHD1 is the dendritic- and myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx. Nature 474, 654–657 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Lahouassa, H. et al. SAMHD1 restricts the replication of human immunodeficiency virus type 1 by depleting the intracellular pool of deoxynucleoside triphosphates. Nat. Immunol. 13, 223–228 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  18. White, T. E. et al. The retroviral restriction ability of SAMHD1, but not its deoxynucleotide triphosphohydrolase activity, is regulated by phosphorylation. Cell Host Microbe 13, 441–451 (2013).

    CAS  PubMed  Google Scholar 

  19. Welbourn, S., Dutta, S. M., Semmes, O. J. & Strebel, K. Restriction of virus infection but not catalytic dNTPase activity is regulated by phosphorylation of SAMHD1. J. Virol. 87, 11516–11524 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Welbourn, S. & Strebel, K. Low dNTP levels are necessary but may not be sufficient for lentiviral restriction by SAMHD1. Virology 488, 271–277 (2016).

    CAS  PubMed  Google Scholar 

  21. Ryoo, J. et al. The ribonuclease activity of SAMHD1 is required for HIV-1 restriction. Nat. Med. 20, 936–941 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  22. Gramberg, T. et al. Restriction of diverse retroviruses by SAMHD1. Retrovirology 10, 26 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  23. Herrmann, A., Happel, A. U. & Gramberg, T. SAMHD1 in retroviral restriction and innate immune sensing—should we leash the hound? Curr. HIV Res. 14, 225–234 (2016).

    CAS  PubMed  Google Scholar 

  24. Sze, A. et al. Host restriction factor SAMHD1 limits human T cell leukemia virus type 1 infection of monocytes via STING-mediated apoptosis. Cell Host Microbe 14, 422–434 (2013).

    CAS  PubMed  Google Scholar 

  25. Badia, R. et al. Inhibition of herpes simplex virus type 1 by the CDK6 inhibitor PD-0332991 (palbociclib) through the control of SAMHD1. J. Antimicrob. Chemother. 71, 387–394 (2016).

    CAS  PubMed  Google Scholar 

  26. Chen, Z. et al. Inhibition of hepatitis B virus replication by SAMHD1. Biochem. Biophys. Res. Commun. 450, 1462–1468 (2014).

    CAS  PubMed  Google Scholar 

  27. Hollenbaugh, J. A. et al. Host factor SAMHD1 restricts DNA viruses in non-dividing myeloid cells. PLoS Pathog. 9, e1003481 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Jeong, G. U., Park, I. H., Ahn, K. & Ahn, B. Y. Inhibition of hepatitis B virus replication by a dNTPase-dependent function of the host restriction factor SAMHD1. Virology 495, 71–78 (2016).

    CAS  PubMed  Google Scholar 

  29. Kim, E. T., White, T. E., Brandariz-Nunez, A., Diaz-Griffero, F. & Weitzman, M. D. SAMHD1 restricts herpes simplex virus 1 in macrophages by limiting DNA replication. J. Virol. 87, 12949–12956 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. Sommer, A. F. et al. Restrictive influence of SAMHD1 on hepatitis B virus life cycle. Sci. Rep. 6, 26616 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  31. Sinzger, C., Digel, M. & Jahn, G. Cytomegalovirus cell tropism. Curr. Top. Microbiol. Immunol. 325, 63–83 (2008).

    CAS  PubMed  Google Scholar 

  32. Sinzger, C., Plachter, B., Grefte, A., The, T. H. & Jahn, G. Tissue macrophages are infected by human cytomegalovirus in vivo. J. Infect. Dis. 173, 240–245 (1996).

    CAS  PubMed  Google Scholar 

  33. Ibanez, C. E., Schrier, R., Ghazal, P., Wiley, C. & Nelson, J. A. Human cytomegalovirus productively infects primary differentiated macrophages. J. Virol. 65, 6581–6588 (1991).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. Minton, E. J., Tysoe, C., Sinclair, J. H. & Sissons, J. G. Human cytomegalovirus infection of the monocyte/macrophage lineage in bone marrow. J. Virol. 68, 4017–4021 (1994).

    CAS  PubMed  PubMed Central  Google Scholar 

  35. Sinzger, C. et al. Macrophage cultures are susceptible to lytic productive infection by endothelial-cell-propagated human cytomegalovirus strains and present viral IE1 protein to CD4+ T cells despite late downregulation of MHC class II molecules. J. Gen. Virol. 87, 1853–1862 (2006).

    CAS  PubMed  Google Scholar 

  36. St Gelais, C. & Wu, L. SAMHD1: a new insight into HIV-1 restriction in myeloid cells. Retrovirology 8, 55 (2011).

    Google Scholar 

  37. Berger, G. et al. Functional analysis of the relationship between Vpx and the restriction factor SAMHD1. J. Biol. Chem. 287, 41210–41217 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  38. Hofmann, H. et al. The Vpx lentiviral accessory protein targets SAMHD1 for degradation in the nucleus. J. Virol. 86, 12552–12560 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  39. Wittmann, S. et al. Phosphorylation of murine SAMHD1 regulates its antiretroviral activity. Retrovirology 12, 103 (2015).

    PubMed  PubMed Central  Google Scholar 

  40. Baldauf, H. M. et al. SAMHD1 restricts HIV-1 infection in resting CD4+ T cells. Nat. Med. 18, 1682–1687 (2012).

    CAS  PubMed  Google Scholar 

  41. Le, V. T., Trilling, M., Wilborn, M., Hengel, H. & Zimmermann, A. Human cytomegalovirus interferes with signal transducer and activator of transcription (STAT) 2 protein stability and tyrosine phosphorylation. J. Gen. Virol. 89, 2416–2426 (2008).

    CAS  PubMed  Google Scholar 

  42. Marshall, E. E. & Geballe, A. P. Multifaceted evasion of the interferon response by cytomegalovirus. J. Interferon Cytokine Res. 29, 609–619 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  43. Paulus, C., Krauss, S. & Nevels, M. A human cytomegalovirus antagonist of type I IFN-dependent signal transducer and activator of transcription signaling. Proc. Natl Acad. Sci. USA 103, 3840–3845 (2006).

    CAS  PubMed  Google Scholar 

  44. Riess, M. et al. Interferons induce expression of SAMHD1 in monocytes through down-regulation of miR-181a and miR-30a. J. Biol. Chem. 292, 264–277 (2017).

    CAS  PubMed  Google Scholar 

  45. St Gelais, C. et al. SAMHD1 restricts HIV-1 infection in dendritic cells (DCs) by dNTP depletion, but its expression in DCs and primary CD4+ T-lymphocytes cannot be upregulated by interferons. Retrovirology 9, 105 (2012).

    Google Scholar 

  46. Pauls, E. et al. Palbociclib, a selective inhibitor of cyclin-dependent kinase4/6, blocks HIV-1 reverse transcription through the control of sterile α motif and HD domain-containing protein-1 (SAMHD1) activity. AIDS 28, 2213–2222 (2014).

    CAS  PubMed  Google Scholar 

  47. He, Z. et al. The human cytomegalovirus UL97 protein is a protein kinase that autophosphorylates on serines and threonines. J. Virol. 71, 405–411 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  48. Oberstein, A., Perlman, D. H., Shenk, T. & Terry, L. J. Human cytomegalovirus pUL97 kinase induces global changes in the infected cell phosphoproteome. Proteomics 15, 2006–2022 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Prichard, M. N. Function of human cytomegalovirus UL97 kinase in viral infection and its inhibition by maribavir. Rev. Med. Virol. 19, 215–229 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  50. Prichard, M. N. et al. A recombinant human cytomegalovirus with a large deletion in UL97 has a severe replication deficiency. J. Virol. 73, 5663–5670 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  51. Biron, K. K. et al. Potent and selective inhibition of human cytomegalovirus replication by 1263W94, a benzimidazole l-riboside with a unique mode of action. Antimicrob. Agents Chemother. 46, 2365–2372 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  52. Kaspari, M. et al. Proteasome inhibitor MG132 blocks viral DNA replication and assembly of human cytomegalovirus. FEBS Lett. 582, 666–672 (2008).

    CAS  PubMed  Google Scholar 

  53. Kalejta, R. F. & Shenk, T. Manipulation of the cell cycle by human cytomegalovirus. Front. Biosci. 7, d295–d306 (2002).

    CAS  PubMed  Google Scholar 

  54. Spector, D. H. Human cytomegalovirus riding the cell cycle. Med. Microbiol. Immunol. 204, 409–419 (2015).

    CAS  PubMed  Google Scholar 

  55. Bresnahan, W. A., Boldogh, I., Chi, P., Thompson, E. A. & Albrecht, T. Inhibition of cellular Cdk2 activity blocks human cytomegalovirus replication. Virology 231, 239–247 (1997).

    CAS  PubMed  Google Scholar 

  56. Bresnahan, W. A., Boldogh, I., Thompson, E. A. & Albrecht, T. Human cytomegalovirus inhibits cellular DNA synthesis and arrests productively infected cells in late G1. Virology 224, 150–160 (1996).

    CAS  PubMed  Google Scholar 

  57. Chen, Z., Knutson, E., Kurosky, A. & Albrecht, T. Degradation of p21cip1 in cells productively infected with human cytomegalovirus. J. Virol. 75, 3613–3625 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  58. Jault, F. M. et al. Cytomegalovirus infection induces high levels of cyclins, phosphorylated Rb, and p53, leading to cell cycle arrest. J. Virol. 69, 6697–6704 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  59. Salvant, B. S., Fortunato, E. A. & Spector, D. H. Cell cycle dysregulation by human cytomegalovirus: influence of the cell cycle phase at the time of infection and effects on cyclin transcription. J. Virol. 72, 3729–3741 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  60. Wiebusch, L. & Hagemeier, C. The human cytomegalovirus immediate early 2 protein dissociates cellular DNA synthesis from cyclin-dependent kinase activation. EMBO J. 20, 1086–1098 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  61. Sanchez, V., McElroy, A. K. & Spector, D. H. Mechanisms governing maintenance of Cdk1/cyclin B1 kinase activity in cells infected with human cytomegalovirus. J. Virol. 77, 13214–13224 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  62. Hu, J. et al. Cyclin E2–CDK2 mediates SAMHD1 phosphorylation to abrogate its restriction of HBV replication in hepatoma cells. FEBS Lett. 592, 1893–1904 (2018).

    CAS  PubMed  Google Scholar 

  63. Kalejta, R. F., Bechtel, J. T. & Shenk, T. Human cytomegalovirus pp71 stimulates cell cycle progression by inducing the proteasome-dependent degradation of the retinoblastoma family of tumor suppressors. Mol. Cell. Biol. 23, 1885–1895 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Kalejta, R. F. & Shenk, T. The human cytomegalovirus UL82 gene product (pp71) accelerates progression through the G1 phase of the cell cycle. J. Virol. 77, 3451–3459 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  65. Kalejta, R. F. & Shenk, T. Proteasome-dependent, ubiquitin-independent degradation of the Rb family of tumor suppressors by the human cytomegalovirus pp71 protein. Proc. Natl Acad. Sci. USA 100, 3263–3268 (2003).

    CAS  PubMed  Google Scholar 

  66. Caffarelli, N., Fehr, A. R. & Yu, D. Cyclin A degradation by primate cytomegalovirus protein pUL21a counters its innate restriction of virus replication. PLoS Pathog. 9, e1003825 (2013).

    PubMed  PubMed Central  Google Scholar 

  67. Eifler, M. et al. PUL21a–cyclin A2 interaction is required to protect human cytomegalovirus-infected cells from the deleterious consequences of mitotic entry. PLoS Pathog. 10, e1004514 (2014).

    PubMed  PubMed Central  Google Scholar 

  68. Qian, Z., Leung-Pineda, V., Xuan, B., Piwnica-Worms, H. & Yu, D. Human cytomegalovirus protein pUL117 targets the mini-chromosome maintenance complex and suppresses cellular DNA synthesis. PLoS Pathog. 6, e1000814 (2010).

    PubMed  PubMed Central  Google Scholar 

  69. Micochova, P. et al. A G1-like state allows HIV-1 to bypass SAMHD1 restriction in macrophages. EMBO J. 36, 604–616 (2017).

    Google Scholar 

  70. Marschall, M. et al. Cellular p32 recruits cytomegalovirus kinase pUL97 to redistribute the nuclear lamina. J. Biol. Chem. 280, 33357–33367 (2005).

    CAS  PubMed  Google Scholar 

  71. Steingruber, M. et al. Proteomic interaction patterns between human cyclins, the cyclin-dependent kinase ortholog pUL97 and additional cytomegalovirus proteins. Viruses 8, 219 (2016).

    PubMed Central  Google Scholar 

  72. Tramentozzi, E. et al. The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592. Cell Cycle 17, 1–13 (2018).

    Google Scholar 

  73. Sinzger, C. et al. Modification of human cytomegalovirus tropism through propagation in vitro is associated with changes in the viral genome. J. Gen. Virol. 80, 2867–2877 (1999).

    CAS  PubMed  Google Scholar 

  74. Digel, M., Sampaio, K. L., Jahn, G. & Sinzger, C. Evidence for direct transfer of cytoplasmic material from infected to uninfected cells during cell-associated spread of human cytomegalovirus. J. Clin. Virol. 37, 10–20 (2006).

    CAS  PubMed  Google Scholar 

  75. Tischer, B. K., von Einem, J., Kaufer, B. & Osterrieder, N. Two-step red-mediated recombination for versatile high-efficiency markerless DNA manipulation in Escherichia coli. Biotechniques 40, 191–197 (2006).

    CAS  PubMed  Google Scholar 

  76. Sinzger, C. et al. Cloning and sequencing of a highly productive, endotheliotropic virus strain derived from human cytomegalovirus TB40/E. J. Gen. Virol. 89, 359–368 (2008).

    CAS  PubMed  Google Scholar 

  77. Gramberg, T., Sunseri, N. & Landau, N. R. Evidence for an activation domain at the amino terminus of simian immunodeficiency virus Vpx. J. Virol. 84, 1387–1396 (2010).

    CAS  PubMed  Google Scholar 

  78. Bogdanow, B. et al. Human cytomegalovirus tegument protein pp150 acts as a cyclin A2–CDK-dependent sensor of the host cell cycle and differentiation state. Proc. Natl Acad. Sci. USA 110, 17510–17515 (2013).

    CAS  PubMed  Google Scholar 

Download references

Acknowledgements

The authors thank K. Hamprecht for help, critical reading of the manuscript and fruitful discussions, as well as support in measuring and quantifying HCMV genomes; K. Kollender, I. Krotova and S. Wagner for technical assistance; T. Iftner for support and encouragement; the ImageStream and FACS Core Facility of the UKT for help with imaging flow cytometry and cell sorting; the team of the Transfusion Medicine Tübingen (ZKT, T. Bakchoul) for providing Buffy Coat and C. Sinzger, M. Marschall, B. Vetter, M. Winkler and R. Kalejta for providing HCMV constructs and protein kinase inhibitors as well as helpful comments and suggestions. This work was funded in part by basic research support given from the University Hospital Tübingen, Medical Faculty and a DFG (SCHI1073/7-1) grant within the SPP1923 ‘Innate Sensing and Restriction of Retroviruses’ to M.S. T.G. (GR3355/3-1) and J.M. (MI2143/2-1) are also supported by research grants from the DFG. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Author information

Authors and Affiliations

Authors

Contributions

R.B., J.D., I.G., L.W., T.G. and M.S. designed experiments. R.B. peformed the infection and the IFN-α experiments, FACS measurements and RT–qPCR. Transfection experiments and in vitro kinase assays were done by J.D., I.G. and L.W. R.B., J.D., I.G., L.W., T.G. and M.S. analysed the data. J.M., L.W., T.G. and M.S. contributed reagents and analysis tools. R.B. and M.S. wrote the manuscript. M.S. conceived the overall study and developed the manuscript to its final form. All authors contributed to manuscript editing, read and approved the final manuscript draft.

Corresponding author

Correspondence to Michael Schindler.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–9, Supplementary References and raw immunoblot data.

Reporting Summary

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Businger, R., Deutschmann, J., Gruska, I. et al. Human cytomegalovirus overcomes SAMHD1 restriction in macrophages via pUL97. Nat Microbiol 4, 2260–2272 (2019). https://doi.org/10.1038/s41564-019-0557-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41564-019-0557-8

This article is cited by

Search

Quick links

Nature Briefing Microbiology

Sign up for the Nature Briefing: Microbiology newsletter — what matters in microbiology research, free to your inbox weekly.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing: Microbiology