PXD038844

PXD038844 is an original dataset announced via ProteomeXchange.

Title	Denitrification by bradyrhizobia under feast and famine and the role of the bc1 complex in securing electrons for N2O reduction
Description	Rhizobia living as microsymbionts inside nodules have stable access to carbon substrates, but also have to survive as free-living bacteria in soil where they are starved for carbon and energy most of the time. Many rhizobia can denitrify, thus switch to anaerobic respiration under low O2 tension using N-oxides as electron acceptors. The cellular machinery regulating this transition is relatively well-known from studies under optimal laboratory conditions, while little is known about this regulation in starved organisms. It is, for example, not known if the strong preference for N2O- over NO3--reduction in bradyrhizobia is retained under carbon limitation. Here we show that starved cultures of a Bradyrhizobium strain with respiration rates 1-18% of well-fed cultures, reduced all available N2O before touching provided NO3-. These organisms, which carry out complete denitrification, have the periplasmic nitrate reductase NapA but lack the membrane-bound nitrate reductase NarG. Proteomics showed similar levels of NapA and NosZ (N2O reductase), excluding that the lack of NO3- reduction was due to low NapA abundance. Instead, this points to a metabolic-level phenomenon where the bc1 complex, which channels electrons to NosZ via cytochromes, is a much stronger competitor for electrons from the quinol pool than the NapC enzyme, which provides electrons to NapA via NapB. The results contrast the general notion that NosZ activity diminishes under carbon limitation and suggest that bradyrhizobia carrying NosZ can act as strong sinks for N2O under natural conditions, implying that this criterion should be considered in the development of biofertilizers.
HostingRepository	PRIDE
AnnounceDate	2023-11-14
AnnouncementXML	Submission_2023-11-14_08:43:55.622.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Magnus Arntzen
SpeciesList	scientific name: Bradyrhizobium sp. HAMBI 2125; NCBI TaxID: 2164133;
ModificationList	acetylated residue; monohydroxylated residue; iodoacetamide derivatized residue
Instrument	Q Exactive

Revision	Datetime	Status	ChangeLog Entry
0	2022-12-14 21:56:30	ID requested
1	2023-03-11 11:27:56	announced
⏵ 2	2023-11-14 08:43:59	announced	2023-11-14: Updated project metadata.

Gao Y, Ø, verlie Arntzen M, Kjos M, Bakken LR, Frosteg, å, rd Å, O Reduction. Appl Environ Microbiol, 89(2):e0174522(2023) [pubmed]

submitter keyword: denitrification,bradyrhizobia

Åsa Frostegård
contact affiliation	Faculty of Chemistry, Biotechnology and Food Science Norwegian University of Life Sciences Post Office Box 5003 1432, Ås Norway
contact email	asa.frostegard@nmbu.no
lab head
Magnus Arntzen
contact affiliation	Norwegian University of Life Sciences
contact email	magnus.arntzen@nmbu.no
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD038844
     1. Label: PRIDE project
     2. Name: Denitrification by bradyrhizobia under feast and famine and the role of the bc1 complex in securing electrons for N2O reduction