4LOW

Structure and identification of a pterin dehydratase-like protein as a RuBisCO assembly factor in the alpha-carboxysome

Summary for 4LOW

• Entry DOI: 10.2210/pdb4low/pdb
• Descriptor: acRAF, FORMIC ACID, NICKEL (II) ION, ... (4 entities in total)
• Functional Keywords: pcd, pterin-4a-carbinolamine dehydratase-like, unknown function
• Biological source: Thiomonas intermedia
• Total number of polymer chains: 2
• Total formula weight: 19834.98

Authors

Wheatley, N.M.,Gidaniyan, S.D.,Cascio, D.,Yeates, T.O. (deposition date: 2013-07-13, release date: 2013-09-11, Last modification date: 2024-02-28)

Primary citation

Wheatley, N.M.,Sundberg, C.D.,Gidaniyan, S.D.,Cascio, D.,Yeates, T.O.
Structure and Identification of a Pterin Dehydratase-like Protein as a Ribulose-bisphosphate Carboxylase/Oxygenase (RuBisCO) Assembly Factor in the alpha-Carboxysome.
J.Biol.Chem., 289:7973-7981, 2014

PubMed Abstract: Carboxysomes are proteinaceous bacterial microcompartments that increase the efficiency of the rate-limiting step in carbon fixation by sequestering reaction substrates. Typically, α-carboxysomes are genetically encoded as a single operon expressing the structural proteins and the encapsulated enzymes of the microcompartment. In addition, depending on phylogeny, as many as 13 other genes are found to co-occur near or within α-carboxysome operons. One of these genes codes for a protein with distant homology to pterin-4α-carbinolamine dehydratase (PCD) enzymes. It is present in all α-carboxysome containing bacteria and has homologs in algae and higher plants. Canonical PCDs play an important role in amino acid hydroxylation, a reaction not associated with carbon fixation. We determined the crystal structure of an α-carboxysome PCD-like protein from the chemoautotrophic bacterium Thiomonas intermedia K12, at 1.3-Å resolution. The protein retains a three-dimensional fold similar to canonical PCDs, although the prominent active site cleft present in PCD enzymes is disrupted in the α-carboxysome PCD-like protein. Using a cell-based complementation assay, we tested the PCD-like proteins from T. intermedia and two additional bacteria, and found no evidence for PCD enzymatic activity. However, we discovered that heterologous co-expression of the PCD-like protein from Halothiobacillus neapolitanus with RuBisCO and GroELS in Escherichia coli increased the amount of soluble, assembled RuBisCO recovered from cell lysates compared with co-expression of RuBisCO with GroELS alone. We conclude that this conserved PCD-like protein, renamed here α-carboxysome RuBisCO assembly factor (or acRAF), is a novel RuBisCO chaperone integral to α-carboxysome function.

PubMed: 24459150
DOI: 10.1074/jbc.M113.531236

Experimental method

X-RAY DIFFRACTION (1.3 Å)