Alex Loy Profile picture
Aug 31, 2020 25 tweets 23 min read
Hey geomicrobiology and microbiome tweeps!

Do you know that the sulfosugar #sulfoquinovose (SQ) is a ubiquitous microbial nutrient in the environment and in a vegetarian diet?

No?

Here comes some SQ propaganda…a thread

#sulfurcycle #carboncycle #H2S #microbiome #diet Image
First, for #sulfoquinovose newbies, I very much recommend the wonderful review by Ethan Goddard-Borger @ethangbaus & Spencer Williams @sjwill99

Sulfoquinovose in the biosphere: occurrence, metabolism and functions portlandpress.com/biochemj/artic…
#sulfoquinovose is a sulfonated glucose and most often found as polar head group of sulfoquinovosyl diacylglycerol (SQDG), a ubiquitous sulfolipid in the photosynthetic membranes of all green land plants, algae, dinoflagellates, and cyanobacteria Image
SQDG is one of the most abundant organic sulfur compounds in the biosphere (production rate of 100,000,000,000 tons per year!) and can represent up to a third of the total lipids in leafy green vegetables #spinach #lettuce #greenonion Image
SQDG #sulfoquinovose are abundant sources of carbon and sulfur in the global nutrient cycles and substrates for the gut microbiota of animals/humans that like their greens

Think of popeye's diet #spinach 🥬as the ultimate #sulfoquinovose boost for your gut microbiota 😉 Image
So how is all the #sulfoquinovose in the environment and our guts degraded?

Thanks to the work of team @DSchleheck

Three bacterial pathways for #sulfoquinovose degradation (sulfoglycolytic pathways) are currently known Image
1. pathway: E.coli and some other Enterobacteriaceae have the sulfo-EMP (Embden-Meyerhof-Parnas) pathway for #sulfoquinovose breakdown and growth

Note that the sulfo-EMP pathway is an additional, analogous pathway to the classical EMP pathway
nature.com/articles/natur…
2. pathway: Pseudomonas putida and some other Proteobacteria have the sulfo-ED pathway for #sulfoquinovose breakdown and growth
pnas.org/content/112/31…
3. pathway: The newly discovered SFT pathway is present in some aerobic and anaerobic Firmicutes and named after its characteristic sulfofructose transaldolase (SFT)
cell.com/iscience/fullt…
All three #sulfoquinovose pathways encode a #sulfoquinovosidase (an alpha-glucosidase in the glycoside hydrolase family 31 - GH31) that cleaves SQ from SQ-glycosides such as SQDG
nature.com/articles/nchem… Image
Aerobic and anaerobic glycolytic #sulfoquinovose (C6) degradation produces a classical C3-compound for growth – either pyruvate or dihydroxyacetone phosphate (DHAP) – and a C3-sulfonate that is excreted – either sulfolactate or dihydroxypropanesulfonate (DHPS) Image
The #sulfoquinovose degradation products #sulfolactate and #DHPS can be utilized by other microorganisms as carbon and/or sulfur sources and energy sources via intracellular production of #sulfite (S oxidation state +4) = electron donor or acceptor
frontiersin.org/articles/10.33…
Sulfonates #DHPS are nutrients and energy sources for sulfur oxidizers in the pelagic ocean

Check out work by the teams of Mary Ann Moran & @BryndanDurham for more info!

nature.com/articles/s4156…
nature.com/articles/s4157… Image
Green-diet-derived #sulfoquinovose is an exclusive growth substrate and thus a potential prebiotic of some abundant bacterial commensals in the human gut

Yet, complete degradation of SQ by cross-feeding of #DHPS produces #H2S

Our new preprint researchsquare.com/article/rs-496…
Eubacterium rectale and Bilophila wadsworthia cooperatively catabolize #sulfoquinovose to acetate and #H2S as main products in human fecal microcosms and in co-culture

Interspecies transfer of #DHPS links a green diet with #H2S production in the gut

#spinach #Popeye Image
Eubacterium rectale ferments #sulfoquinovose to DHPS via the SFT pathway

which is exclusive to E. rectale and few other intestinal Firmicutes species such as Feacalibacterium prausnitzii Image
Across the fecal metatranscriptomes of many individuals
#sulfoquinovose degradation was expressed prevalently and abundantly (top 33% of all microbial pathways) Image
and mostly by Eubacterium rectale and Feacalibacterium prausnitzii Image
Bilophila utilizes #DHPS as electron acceptor via a new oxygen-sensitive glycyl-radical enzyme that releases sulfite from DHPS for anaerobic respiration to #H2S via the DsrABC pathway

The DHPS sulfite-lyase cleaves #DHPS into hydroxyacetone and #sulfite

researchsquare.com/article/rs-496… Image
In parallel, the DHPS sulfite-lyase was also discovered by the team of Yan Zhang, with additional biochemical and structural data

Excitingly, they also describe a DHPS-dehydratase in bacteria that ferment DHPS without #H2S production

pnas.org/content/117/27…
In Bilophila and other bacteria, the DHPS sulfite-lyase is paralogous to isethionate sulfite-lyase, a key enzyme in anaerobic taurine degradation that was also discovered by the teams of @DSchleheck pnas.org/content/116/8/…
and Yan Zhang nature.com/articles/s4146… Image
#metatranscriptome analysis of DsrABC-sulfite reduction and DHPS/isethionate sulfite-lyase activities suggested Bilophila and other Desulfovibrionaceae use mostly #taurine but also #DHPS for #H2S production in the human gut Image
Thanks for reading!

Keep in mind that #sulfoquinovose metabolism is a core physiological attribute of the human gut that is likely modifiable by diet - think of #Popeye #spinach 😉- and contributes to host health

researchsquare.com/article/rs-496…

#H2S #acetate #microbiome #prebiotic Image
ADDENDUM:

#H2S is a Janus-faced molecule

with detrimental

#toxic sciencedirect.com/science/articl…

#mucusbreaker pnas.org/content/112/32…

and beneficial effects

journals.physiology.org/doi/full/10.11…

on the intestinal environment Image
The complex host-endogenous
sciencedirect.com/science/articl…

and microbial processes
link.springer.com/article/10.100…

that regulate intestinal #H2S homeostasis and how they are influenced by #diet or health state are yet insufficiently defined

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