TY - JOUR
T1 - Analysis of the Involvement of the Isoleucine Biosynthesis Pathway in Photoheterotrophic Metabolism of Rhodospirillum rubrum
AU - Bayon-Vicente, Guillaume
AU - Marchand, Elie
AU - Ducrotois, Jeson
AU - Dufrasne, François
AU - Hallez, Regis
AU - Wattiez, Ruddy
AU - Leroy, Baptiste
N1 - Funding Information:
We thank the Biotechnology Unit of Materia Nova (Mons, Belgium) for the kind support and the provision of GC-MS and HPLC equipment.
Funding Information:
This research was funded by the FRIA grant of GB-V (F.R.S-FNRS). This study was sponsored by the “Belgian Fund for Scientific Research (Grand equipment-F.R.S-FNRS).” The bioprofiling platform used for the MRM analyses was supported by the European Regional Development Fund and the Walloon Region, Belgium. EM holds an FRIA fellowship (F.R.S-FRNS) and RH is a Research Associate of the F.R.S-FNRS.
Publisher Copyright:
© Copyright © 2021 Bayon-Vicente, Marchand, Ducrotois, Dufrasne, Hallez, Wattiez and Leroy.
PY - 2021/9/21
Y1 - 2021/9/21
N2 - Purple non-sulfur bacteria (PNSB) are recognized as a highly versatile group of bacteria that assimilate a broad range of carbon sources. Growing heterotrophically, PNSB such as Rhodospirillum rubrum (Rs. rubrum) generate reduced equivalents that are used for biomass production. However, under photoheterotrophic conditions, more reduced electron carriers than required to produce biomass are generated. The excess of reduced equivalents still needs to be oxidized for the metabolism to optimally operate. These metabolic reactions are known as electron sinks. Most PNSB rely on the CO2-fixing Calvin cycle and H2 production to oxidize these reduced equivalents. In addition to these well-described electron sinks, the involvement of some pathways, such as polyhydroxyalkanoate (PHA) biosynthesis, in redox poise is still controversial and requires further studies. Among them, isoleucine biosynthesis has been recently highlighted as one of these potential pathways. Here, we explore the role of isoleucine biosynthesis in Rs. rubrum. Our results demonstrate that the isoleucine content is higher under illuminated conditions and that submitting Rs. rubrum to light stress further increases this phenomenon. Moreover, we explore the production of (p)ppGpp in Rs. rubrum and its potential link with light stress. We further demonstrate that a fully functional isoleucine biosynthesis pathway could be an important feature for the onset of Rs. rubrum growth under photoheterotrophic conditions even in the presence of an exogenous isoleucine source. Altogether, our data suggest that isoleucine biosynthesis could play a key role in redox homeostasis.
AB - Purple non-sulfur bacteria (PNSB) are recognized as a highly versatile group of bacteria that assimilate a broad range of carbon sources. Growing heterotrophically, PNSB such as Rhodospirillum rubrum (Rs. rubrum) generate reduced equivalents that are used for biomass production. However, under photoheterotrophic conditions, more reduced electron carriers than required to produce biomass are generated. The excess of reduced equivalents still needs to be oxidized for the metabolism to optimally operate. These metabolic reactions are known as electron sinks. Most PNSB rely on the CO2-fixing Calvin cycle and H2 production to oxidize these reduced equivalents. In addition to these well-described electron sinks, the involvement of some pathways, such as polyhydroxyalkanoate (PHA) biosynthesis, in redox poise is still controversial and requires further studies. Among them, isoleucine biosynthesis has been recently highlighted as one of these potential pathways. Here, we explore the role of isoleucine biosynthesis in Rs. rubrum. Our results demonstrate that the isoleucine content is higher under illuminated conditions and that submitting Rs. rubrum to light stress further increases this phenomenon. Moreover, we explore the production of (p)ppGpp in Rs. rubrum and its potential link with light stress. We further demonstrate that a fully functional isoleucine biosynthesis pathway could be an important feature for the onset of Rs. rubrum growth under photoheterotrophic conditions even in the presence of an exogenous isoleucine source. Altogether, our data suggest that isoleucine biosynthesis could play a key role in redox homeostasis.
KW - acetic acid
KW - electron sink
KW - isoleucine biosynthesis
KW - light intensity
KW - photoheterotroph
KW - purple bacteria
KW - redox balance
KW - volatile fatty acids (VFA)
UR - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8490811/
UR - http://www.scopus.com/inward/record.url?scp=85115255046&partnerID=8YFLogxK
U2 - 10.3389/fmicb.2021.731976
DO - 10.3389/fmicb.2021.731976
M3 - Article
SN - 1664-302X
VL - 12
JO - Frontiers in Microbiology
JF - Frontiers in Microbiology
M1 - 731976
ER -