Life cycle of a cyanobacterial carboxysome

Hill, N. C. W.; Tay, Jian Wei; Altus, Sabina; Bortz, David M.; Cameron, Jeffrey C.

doi:10.1126/sciadv.aba1269

Cited by 54 publications

(58 citation statements)

References 29 publications

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“…While α-and β-carboxysome aggregation does not result in a high CO2-requiring phenotype (MacCready et al, 2018; Desmarais et al, 2019), we recently found that β-carboxysome aggregation in S. elongatus does result in slower cell growth, cell elongation, and asymmetric cell division; presumably due to decreased carbon-fixation by RuBisCO in these aggregates (Rillema et al, 2020). Moreover, it was recently found that degradation of inactive carboxysomes occurs at polar regions of a cyanobacterial cell (Hill et al, 2020). How the polar localization of carboxysome aggregates, from a lack of a McdAB system, influences carboxysome function and turnover remains unclear.…”

Section: Mcda and Mcdb Maintain Carboxysome Distributions In H Neapomentioning

confidence: 99%

The McdAB system positions α-carboxysomes in proteobacteria

MacCready

Tran²,

Basalla³

et al. 2020

Preprint

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Carboxysomes are protein-based organelles essential for carbon fixation in cyanobacteria and proteobacteria. Previously, we showed that the cyanobacterial nucleoid is utilized as a surface for the equidistant-spacing of β-carboxysomes across cell lengths by a two-component system (McdAB) in the model cyanobacterium Synechococcus elongatus PCC 7942. More recently, we found that McdAB systems are widespread among β-cyanobacteria, which possess β-carboxysomes, but are absent in α-cyanobacteria, which possess structurally distinct α-carboxysomes. Since cyanobacterial α-carboxysomes are thought to have arisen in proteobacteria and were subsequently horizontally transferred into cyanobacteria, this raised the question whether α-carboxysome containing proteobacteria possess a McdAB system for positioning α-carboxysomes. Here, using the model chemoautotrophic proteobacterium H. neapolitanus, we show that a McdAB system distinct from that of β-cyanobacteria operates to position α-carboxysomes across cell lengths. We further show that this system is widespread among α-carboxysome containing proteobacteria and that cyanobacteria likely inherited an α-carboxysome operon from a proteobacterium lacking the mcdAB locus. These results demonstrate that McdAB is a cross-phylum two-component system necessary for positioning α- and β-carboxysomes. The findings have further implications for understanding the positioning of other bacterial protein-based organelles involved in diverse metabolic processes.

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Section: Mcda and Mcdb Maintain Carboxysome Distributions In H Neapomentioning

confidence: 99%

The McdAB system positions α-carboxysomes in proteobacteria

MacCready

Tran²,

Basalla³

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…Beyond a potential role in dynamics, increased shell flexibility could allow for packing a greater variety of internal enzymes in non-carboxysomal MCPs, or more variable enzyme stoichiometries. The processes that govern MCP assembly and disassembly remain only partially understood, 15,[54][55][56][57] and flexibility could be important for those processes. The flexibility observed in this protein family invites additional questions about microcompartment structure, evolution, and function.…”

Section: Discussionmentioning

confidence: 99%

Symmetry breaking and structural polymorphism in a bacterial microcompartment shell protein for choline utilization

et al. 2020

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Bacterial microcompartments are protein-based organelles that carry out specialized metabolic functions in diverse bacteria. Their outer shells are built from several thousand protein subunits. Some of the architectural principles of bacterial microcompartments have been articulated, with lateral packing of flat hexameric BMC proteins providing the basic foundation for assembly. Nonetheless, a complete understanding has been elusive, partly owing to polymorphic mechanisms of assembly exhibited by most microcompartment types. An earlier study of one homologous BMC shell protein subfamily, EutS/PduU, revealed a profoundly bent, rather than flat, hexameric structure. The possibility of a specialized architectural role was hypothesized, but artifactual effects of crystallization could not be ruled out. Here we report a series of crystal structures of an orthologous protein, CutR, from a glycyl-radical type cholineutilizing microcompartment from the bacterium Streptococcus intermedius. Depending on crystal form, expression construct, and minor mutations, a range of novel quaternary architectures was observed, including two spiral hexagonal assemblies. A new graphical approach helps illuminate the variations in BMC hexameric structure, with results substantiating the idea that the EutS/PduU/CutR subfamily of BMC proteins may endow microcompartment shells with flexible modes of assembly.

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“…CA generates a high CO 2 concentration in the carboxysome. Shell breakage may cause carboxysome loss in cyanobacteria [4]. C4 plants like maize employ a CO 2 concentration mechanism where HCO 3 − is fixed by phospho-enol-pyruvate carboxylase (PEPC) in the mesophyll to produce oxaloacetate, which is reduced to malic acid with NADH + H + as an electron donor.…”

Section: Introductionmentioning

confidence: 99%

“…CA generates a high CO 2 concentration in the carboxysome. Shell breakage may cause carboxysome loss in cyanobacteria [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Thiol Redox Regulation of Plant β-Carbonic Anhydrase

et al. 2020

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β-carbonic anhydrases (βCA) accelerate the equilibrium formation between CO2 and carbonate. Two plant βCA isoforms are targeted to the chloroplast and represent abundant proteins in the range of >1% of chloroplast protein. While their function in gas exchange and photosynthesis is well-characterized in carbon concentrating mechanisms of cyanobacteria and plants with C4-photosynthesis, their function in plants with C3-photosynthesis is less clear. The presence of conserved and surface-exposed cysteinyl residues in the βCA-structure urged to the question whether βCA is subject to redox regulation. Activity measurements revealed reductive activation of βCA1, whereas oxidized βCA1 was inactive. Mutation of cysteinyl residues decreased βCA1 activity, in particular C280S, C167S, C230S, and C257S. High concentrations of dithiothreitol or low amounts of reduced thioredoxins (TRXs) activated oxidized βCA1. TRX-y1 and TRX-y2 most efficiently activated βCA1, followed by TRX-f1 and f2 and NADPH-dependent TRX reductase C (NTRC). High light irradiation did not enhance βCA activity in wildtype Arabidopsis, but surprisingly in βca1 knockout plants, indicating light-dependent regulation. The results assign a role of βCA within the thiol redox regulatory network of the chloroplast.

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Life cycle of a cyanobacterial carboxysome

Cited by 54 publications

References 29 publications

The McdAB system positions α-carboxysomes in proteobacteria

The McdAB system positions α-carboxysomes in proteobacteria

Symmetry breaking and structural polymorphism in a bacterial microcompartment shell protein for choline utilization

Thiol Redox Regulation of Plant β-Carbonic Anhydrase

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