P45690 · CSOSB_HALNC

Function

function

One of shell proteins of the carboxysome, a polyhedral inclusion where RuBisCO (ribulose bisphosphate carboxylase, ccbL-ccbS) is sequestered. Assembles into hexamers which make sheets that form the facets of the polyhedral carboxysome (By similarity).
The shell probably limits the diffusion of CO2 into and out of the carboxysome (Probable). There are estimated to be 540 CsoS1B proteins per carboxysome (Ref.4).
Unlike beta-carboxysomes, alpha-carboxysomes (Cb) can form without cargo protein. CsoS2 is essential for Cb formation and is also capable of targeting foreign proteins to the Cb. The Cb shell assembles with the aid of CsoS2; CsoS1A, CsoS1B and CsoS1C form the majority of the shell while CsoS4A and CsoS4B form vertices. CsoS1D forms pseudohexamers that probably control metabolite flux into and out of the shell.

Biotechnology

Expression of 10 genes for alpha-carboxysome (Cb) proteins (cbbL-cbbS-csoS2-csoS3-csoS4A-csoS4B-csoS1C-csoS1A-csoS1B-csoS1D) in E.coli generates compartments that resemble Cb, contain RuBisCO and have its catalytic activity, showing it is possible to make artificial, functional Cb using these 10 genes. Cargo proteins can be targeted to these organelles (PubMed:22184212, PubMed:30305640).
Artificial Cb assembly in E.coli requires csoS2-csoS4A-csoS4B-csoS1C-csoS1A-csoS1B-csoS1D (but not the gene for carbonic anhydrase, csoS3). Targeting proteins to the organelle requires at least one of the CsoS2 C-repeats; 3 repeats gives the best localization. A nanoreactor of the Cb shell proteins has been engineered which generates H2 using a ferredoxin-hydrogenase fusion (AC P07839-Q9FYU1) and a flavodoxin/ferredoxin--NADP reductase (AC A0A0K3QZA5) targeted separately to the Cb; the hydrogenase has first to be matured and activated by HydGXEF (AC Q8EAH9, Q8EAH8, Q8EAH7 and Q8EAH6 respectively). Encapsulation increases H2 production about 20% during anaerobic growth, and over 4-fold more during aerobic growth (PubMed:33116131).

GO annotations

AspectTerm
Cellular Componentcarboxysome
Biological Processcarbon fixation

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Carboxysome shell protein CsoS1B

Gene names

    • Name
      csoS1B
    • Synonyms
      Orf3
    • Ordered locus names
      Hneap_0914

Organism names

Accessions

  • Primary accession
    P45690
  • Secondary accessions
    • D0KZ84

Proteomes

Subcellular Location

Carboxysome
Note: This bacterium makes alpha-type carboxysomes.

Keywords

Phenotypes & Variants

Disruption phenotype

Required for growth in ambient air.

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00002015131-110Carboxysome shell protein CsoS1B

Interaction

Subunit

Homohexamer with a small central pore (By similarity).
Interacts with the N-terminus (residues 1-136) of RuBisCO (CbbL) (PubMed:30305640).

Protein-protein interaction databases

Structure

Family & Domains

Features

Showing features for domain.

TypeIDPosition(s)Description
Domain8-93BMC

Domain

The tight homohexamer forms a small pore which is positively charged.

Sequence similarities

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    110
  • Mass (Da)
    11,301
  • Last updated
    1999-07-15 v3
  • Checksum
    D302DC82CAFB9CFE
MATTHGIALGMIETRGLVPAIEAADAMTKAAEVRLVGRSFVGGGYVTVMVRGETGAVNAAVRAGADACERVGDGLVAAHIIARVHSEVEIILPETPEDSDSAWCIANLNS

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AF038430
EMBL· GenBank· DDBJ
AAC32557.1
EMBL· GenBank· DDBJ
Genomic DNA
CP001801
EMBL· GenBank· DDBJ
ACX95757.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

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