A new type of phasin characterized by the presence of a helix-hairpin-helix domain is required for normal polyhydroxybutyrate accumulation and granule organization in Caulobacter crescentus

Bacteria frequently store excess carbon in hydrophobic granules of polyhydroxybutyrate (PHB) that in some growth conditions can occupy most of the cytoplasmic space. Different types of proteins associate to the surface of the granules, mainly enzymes involved in the synthesis and utilization of the...

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Bibliographic Details
Published in:Molecular microbiology 2023-09, Vol.120 (3), p.307-323
Main Authors: Salinas, Ana Laura, Osorio, Aurora, Legorreta-Hissner, Tonatiuh, Lara-Martinez, Reyna, Jimenez-Garcia, Luis Felipe, Camarena, Laura, Poggio, Sebastian
Format: Article
Language:English
Subjects:
Accumulation
Bacteria
Caulobacter crescentus
Chemical synthesis
Enzymes
Granular materials
Growth conditions
Hydrophobicity
Polyhydroxybutyrate
Polyhydroxybutyric acid
Polymers
Proteins
Proteomics
Stationary phase
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Summary:Bacteria frequently store excess carbon in hydrophobic granules of polyhydroxybutyrate (PHB) that in some growth conditions can occupy most of the cytoplasmic space. Different types of proteins associate to the surface of the granules, mainly enzymes involved in the synthesis and utilization of the reserve polymer and a diverse group of proteins known as phasins. Phasins have different functions, among which are regulating the size and number of the granules, modulating the activity of the granule-associated enzymes and helping in the distribution of the granules inside the cell. Caulobacter crescentus is an oligotrophic bacterium that shows several morphological and regulatory traits that allow it to grow in very nutrient-diluted environments. Under these conditions, storage compounds should be particularly relevant for survival. In this work, we show an initial proteomic characterization of the PHB granules and describe a new type of phasin (PhaH) characterized by the presence of an N-terminal hydrophobic helix followed by a helix-hairpin-helix (HhH) domain. The hydrophobic helix is required for maximal PHB accumulation and maintenance during the stationary phase while the HhH domain is involved in determining the size of the PHB granules and their distribution in the cell.
ISSN:0950-382X
1365-2958
DOI:10.1111/mmi.15124