[SCAN] Identification of the siroheme biosynthesis pathway in Staphylococcus aureus
Marco Videira
| When |
07 Oct, 2020
from
12:00 pm to 01:00 pm |
|---|---|
| Contact Name | Rita Abranches |
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Title: Identification of the siroheme biosynthesis pathway in Staphylococcus aureus
Speaker: Marco Videira
Host: Filipe Folgosa
Abstrat: Siroheme is a modified tetrapyrrole and one of the components that allow the reduction of nitrite and sulfite by nitrite and sulfite reductases, respectively. It is known that Staphylococcus aureus encodes a nitrite reductase, but so far, nothing was shown regarding the synthesis of the siroheme prosthetic group. Here, we show that Staphylococcus aureus produces sirohaem through a pathway formed by three independent enzymes. The first gene annotated as cysG encodes a uroporphyrinogen III methytransferase, a second gene annotated as cysG encodes a precorrin-2 dehydrogenase and a last gene that was annotated as nirR and previously thought to be a transcriptional regulator, encodes a protein with sirohydrochlorin ferrochelatase activity. Within bacteria, sirohaem synthesis may occur via one, two or three enzymes, and we propose to name the correspondent pathways as Types 1, 2 and 3, respectively. A phylogenetic analysis revealed that Type 1 is the most used pathway in Gammaproteobacteria and Streptomycetales, Type 2 predominates in Fibrobacteres and Vibrionales, and Type 3 predominates in Firmicutes of the Bacillales order. Altogether, we concluded that the current distribution of siroheme pathways within bacteria, which changes at the genus or species level and within taxa, seems to be the result of evolutionary multiple fusion/fission events.
