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Hoang Y, Azaldegui CA, Dow RE, Ghalmi M, Biteen JS, Vecchiarelli AG. An experimental framework to assess biomolecular condensates in bacteria. Nat Commun 2024; 15:3222. [PMID: 38622124 PMCID: PMC11018776 DOI: 10.1038/s41467-024-47330-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 03/28/2024] [Indexed: 04/17/2024] Open
Abstract
High-resolution imaging of biomolecular condensates in living cells is essential for correlating their properties to those observed through in vitro assays. However, such experiments are limited in bacteria due to resolution limitations. Here we present an experimental framework that probes the formation, reversibility, and dynamics of condensate-forming proteins in Escherichia coli as a means to determine the nature of biomolecular condensates in bacteria. We demonstrate that condensates form after passing a threshold concentration, maintain a soluble fraction, dissolve upon shifts in temperature and concentration, and exhibit dynamics consistent with internal rearrangement and exchange between condensed and soluble fractions. We also discover that an established marker for insoluble protein aggregates, IbpA, has different colocalization patterns with bacterial condensates and aggregates, demonstrating its potential applicability as a reporter to differentiate the two in vivo. Overall, this framework provides a generalizable, accessible, and rigorous set of experiments to probe the nature of biomolecular condensates on the sub-micron scale in bacterial cells.
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Affiliation(s)
- Y Hoang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - Rachel E Dow
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Maria Ghalmi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Julie S Biteen
- Doctoral Program in Chemical Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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Basalla JL, Mak CA, Byrne JA, Ghalmi M, Hoang Y, Vecchiarelli AG. Dissecting the phase separation and oligomerization activities of the carboxysome positioning protein McdB. eLife 2023; 12:e81362. [PMID: 37668016 PMCID: PMC10554743 DOI: 10.7554/elife.81362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 09/01/2023] [Indexed: 09/06/2023] Open
Abstract
Across bacteria, protein-based organelles called bacterial microcompartments (BMCs) encapsulate key enzymes to regulate their activities. The model BMC is the carboxysome that encapsulates enzymes for CO2 fixation to increase efficiency and is found in many autotrophic bacteria, such as cyanobacteria. Despite their importance in the global carbon cycle, little is known about how carboxysomes are spatially regulated. We recently identified the two-factor system required for the maintenance of carboxysome distribution (McdAB). McdA drives the equal spacing of carboxysomes via interactions with McdB, which associates with carboxysomes. McdA is a ParA/MinD ATPase, a protein family well studied in positioning diverse cellular structures in bacteria. However, the adaptor proteins like McdB that connect these ATPases to their cargos are extremely diverse. In fact, McdB represents a completely unstudied class of proteins. Despite the diversity, many adaptor proteins undergo phase separation, but functional roles remain unclear. Here, we define the domain architecture of McdB from the model cyanobacterium Synechococcus elongatus PCC 7942, and dissect its mode of biomolecular condensate formation. We identify an N-terminal intrinsically disordered region (IDR) that modulates condensate solubility, a central coiled-coil dimerizing domain that drives condensate formation, and a C-terminal domain that trimerizes McdB dimers and provides increased valency for condensate formation. We then identify critical basic residues in the IDR, which we mutate to glutamines to solubilize condensates. Finally, we find that a condensate-defective mutant of McdB has altered association with carboxysomes and influences carboxysome enzyme content. The results have broad implications for understanding spatial organization of BMCs and the molecular grammar of protein condensates.
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Affiliation(s)
- Joseph L Basalla
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann ArborAnn ArborUnited States
| | - Claudia A Mak
- Department of Biological Chemistry, University of Michigan-Ann ArborAnn ArborUnited States
| | - Jordan A Byrne
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann ArborAnn ArborUnited States
| | - Maria Ghalmi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann ArborAnn ArborUnited States
| | - Y Hoang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann ArborAnn ArborUnited States
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann ArborAnn ArborUnited States
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Pulianmackal LT, Limcaoco JMI, Ravi K, Yang S, Zhang J, Tran MK, Ghalmi M, O'Meara MJ, Vecchiarelli AG. Multiple ParA/MinD ATPases coordinate the positioning of disparate cargos in a bacterial cell. Nat Commun 2023; 14:3255. [PMID: 37277398 DOI: 10.1038/s41467-023-39019-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/22/2023] [Indexed: 06/07/2023] Open
Abstract
In eukaryotes, linear motor proteins govern intracellular transport and organization. In bacteria, where linear motors involved in spatial regulation are absent, the ParA/MinD family of ATPases organize an array of genetic- and protein-based cellular cargos. The positioning of these cargos has been independently investigated to varying degrees in several bacterial species. However, it remains unclear how multiple ParA/MinD ATPases can coordinate the positioning of diverse cargos in the same cell. Here, we find that over a third of sequenced bacterial genomes encode multiple ParA/MinD ATPases. We identify an organism (Halothiobacillus neapolitanus) with seven ParA/MinD ATPases, demonstrate that five of these are each dedicated to the spatial regulation of a single cellular cargo, and define potential specificity determinants for each system. Furthermore, we show how these positioning reactions can influence each other, stressing the importance of understanding how organelle trafficking, chromosome segregation, and cell division are coordinated in bacterial cells. Together, our data show how multiple ParA/MinD ATPases coexist and function to position a diverse set of fundamental cargos in the same bacterial cell.
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Affiliation(s)
- Lisa T Pulianmackal
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jose Miguel I Limcaoco
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Keerthikka Ravi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Sinyu Yang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jeffrey Zhang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mimi K Tran
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Maria Ghalmi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Matthew J O'Meara
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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Vecchiarelli A, Hoang Y, Azaldegui C, Ghalmi M, Biteen J. An experimental framework to assess biomolecular condensates in bacteria. Res Sq 2023:rs.3.rs-2725220. [PMID: 37066349 PMCID: PMC10104261 DOI: 10.21203/rs.3.rs-2725220/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
High-resolution imaging of biomolecular condensates in living cells is essential for correlating their properties to those observed through in vitro assays. However, such experiments are limited in bacteria due to resolution limitations. Here we present an experimental framework that probes the formation, reversibility, and dynamics of condensate-forming proteins in Escherichia coli as a means to determine the nature of biomolecular condensates in bacteria. We demonstrate that condensates form after passing a threshold concentration, maintain a soluble fraction, dissolve upon shifts in temperature and concentration, and exhibit dynamics consistent with internal rearrangement and exchange between condensed and soluble fractions. We also discovered that an established marker for insoluble protein aggregates, IbpA, has different colocalization patterns with bacterial condensates and aggregates, demonstrating its applicability as a reporter to differentiate the two in vivo. Overall, this framework provides a generalizable, accessible, and rigorous set of experiments to probe the nature of biomolecular condensates on the sub-micron scale in bacterial cells.
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Hoang Y, Azaldegui CA, Ghalmi M, Biteen JS, Vecchiarelli AG. An experimental framework to assess biomolecular condensates in bacteria. bioRxiv 2023:2023.03.22.533878. [PMID: 36993636 PMCID: PMC10055370 DOI: 10.1101/2023.03.22.533878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
High-resolution imaging of biomolecular condensates in living cells is essential for correlating their properties to those observed through in vitro assays. However, such experiments are limited in bacteria due to resolution limitations. Here we present an experimental framework that probes the formation, reversibility, and dynamics of condensate-forming proteins in Escherichia coli as a means to determine the nature of biomolecular condensates in bacteria. We demonstrate that condensates form after passing a threshold concentration, maintain a soluble fraction, dissolve upon shifts in temperature and concentration, and exhibit dynamics consistent with internal rearrangement and exchange between condensed and soluble fractions. We also discovered that an established marker for insoluble protein aggregates, IbpA, has different colocalization patterns with bacterial condensates and aggregates, demonstrating its applicability as a reporter to differentiate the two in vivo. Overall, this framework provides a generalizable, accessible, and rigorous set of experiments to probe the nature of biomolecular condensates on the sub-micron scale in bacterial cells.
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Affiliation(s)
- Y Hoang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
- Equal contribution
| | - Christopher A. Azaldegui
- Doctoral Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109 USA
- Equal contribution
| | - Maria Ghalmi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Julie S. Biteen
- Doctoral Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109 USA
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109 USA
| | - Anthony G. Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 USA
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Ghalmi M. Integrating protection and human rights into relief and development: the case of Burundi. Refugee Survey Quarterly 1999. [DOI: 10.1093/rsq/18.1.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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