Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>

Polyhydroxybutyrate (PHB) is a carbon and energy reserve polymer in various prokaryotic species. We determined that, when grown with mannitol as the sole carbon source, <i>Bradyrhizobium diazoefficiens</i> produces a homopolymer composed only of 3-hydroxybutyrate units (PHB). Conditions...

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Autores principales: Quelas, Juan Ignacio, Mesa, S., Mongiardini, Elías Javier, Jendrossek, D., Lodeiro, Aníbal Roberto
Formato: Articulo
Lenguaje:Inglés
Publicado: 2016
Materias:
Ciencias Exactas
Bradyrhizobium diazoefficiens
Polyhydroxybutyrate
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/86639
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-86639
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Exactas
Bradyrhizobium diazoefficiens
Polyhydroxybutyrate
spellingShingle Ciencias Exactas
Bradyrhizobium diazoefficiens
Polyhydroxybutyrate
Quelas, Juan Ignacio
Mesa, S.
Mongiardini, Elías Javier
Jendrossek, D.
Lodeiro, Aníbal Roberto
Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
topic_facet Ciencias Exactas
Bradyrhizobium diazoefficiens
Polyhydroxybutyrate
description Polyhydroxybutyrate (PHB) is a carbon and energy reserve polymer in various prokaryotic species. We determined that, when grown with mannitol as the sole carbon source, <i>Bradyrhizobium diazoefficiens</i> produces a homopolymer composed only of 3-hydroxybutyrate units (PHB). Conditions of oxygen limitation (such as microoxia, oxic stationary phase, and bacteroids inside legume nodules) were permissive for the synthesis of PHB, which was observed as cytoplasmic granules. To study the regulation of PHB synthesis, we generated mutations in the regulator gene <i>phaR</i> and the phasin genes <i>phaP1</i> and <i>phaP4</i>. Under permissive conditions, mutation of <i>phaR</i> impaired PHB accumulation, and a <i>phaP1</i> <i>phaP4</i> double mutant produced more PHB than the wild type, which was accumulated in a single, large cytoplasmic granule. Moreover, PhaR negatively regulated the expression of <i>phaP1</i> and <i>phaP4</i> as well as the expression of <i>phaA1</i> and <i>phaA2</i> (encoding a 3-ketoacyl coenzyme A [CoA] thiolases), <i>phaC1</i> and <i>phaC2</i> (encoding PHB synthases), and fixK<SUB>2</SUB> (encoding a cyclic AMP receptor protein [CRP]/fumarate and nitrate reductase regulator [FNR]-type transcription factor of genes for microoxic lifestyle). In addition to the depressed PHB cycling, <i>phaR</i> mutants accumulated more extracellular polysaccharides and promoted higher plant shoot dry weight and competitiveness for nodulation than the wild type, in contrast to the <i>phaC1</i> mutant strain, which is defective in PHB synthesis. These results suggest that <i>phaR</i> not only regulates PHB granule formation by controlling the expression of phasins and biosynthetic enzymes but also acts as a global regulator of excess carbon allocation and symbiosis by controlling fixK<SUB>2</SUB>.
format Articulo
Articulo
author Quelas, Juan Ignacio
Mesa, S.
Mongiardini, Elías Javier
Jendrossek, D.
Lodeiro, Aníbal Roberto
author_facet Quelas, Juan Ignacio
Mesa, S.
Mongiardini, Elías Javier
Jendrossek, D.
Lodeiro, Aníbal Roberto
author_sort Quelas, Juan Ignacio
title Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
title_short Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
title_full Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
title_fullStr Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
title_full_unstemmed Regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>Bradyrhizobium diazoefficiens</i>
title_sort regulation of polyhydroxybutyrate synthesis in the soil bacterium <i>bradyrhizobium diazoefficiens</i>
publishDate 2016
url http://sedici.unlp.edu.ar/handle/10915/86639
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