A distinct holoenzyme organization for two-subunit pyruvate carboxylase.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 27708276.
- Also identified by DOI 10.1038/ncomms12713 and PMC identifier 5059739.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Pyruvate carboxylase (PC) has important roles in metabolism and is crucial for virulence for some pathogenic bacteria. PC contains biotin carboxylase (BC), carboxyltransferase (CT) and biotin carboxyl carrier protein (BCCP) components. It is a single-chain enzyme in eukaryotes and most bacteria, and functions as a 500 kD homo-tetramer. In contrast, PC is a two-subunit enzyme in a collection of Gram-negative bacteria, with the α subunit containing the BC and the β subunit the CT and BCCP domains, and it is believed that the holoenzyme has α<sub>4</sub>β<sub>4</sub> stoichiometry. We report here the crystal structures of a two-subunit PC from Methylobacillus flagellatus. Surprisingly, our structures reveal an α<sub>2</sub>β<sub>4</sub> stoichiometry, and the overall architecture of the holoenzyme is strikingly different from that of the homo-tetrameric PCs. Biochemical and mutagenesis studies confirm the stoichiometry and other structural observations. Our functional studies in Pseudomonas aeruginosa show that its two-subunit PC is important for colony morphogenesis.
Medical subject headings
- Bacterial Proteins
- Methylobacillus
- Pyruvate Carboxylase