"a (S)-scoulerine 9-O-methyltransferase is an enzyme that catalyzes the chemical reaction
S-adenosyl-L-methionine + (S)-scoulerine <->
****S-adenosyl-L-homocysteine*** +
(S)-tetrahydrocolumbamine"
If berberine inhibits (S)-scoulerine 9-O-methyltransferase, then this can't happen:
S-adenosyl-L-methionine + (S)-scoulerine <->
****S-adenosyl-L-homocysteine*** +
(S)-tetrahydrocolumbamine.
Ultimately this may inhibit quorum sensing also.
"The autoinducer-2 (AI-2) group of ***signalling molecules*** are produced by both Gram positive and Gram negative bacteria as the by-product of a metabolic transformation carried out by the LuxS enzyme.
They are the only non species-specific ***quorum sensing compounds*** presently known in bacteria.
The luxS gene coding for the AI-2 (autoinducer-2) synthase enzyme was found in many important pathogens.
DPD is produced only in the domain Bacteria as a by-product of the activated methyl cycle.
The pathway leading to DPD involves a two-step detoxification of S-adenosylhomocysteine (SAH), namely by a MTA/SAH nucleosidase (also called ***Pfs*** enzyme) and a
S-ribosylhomocysteinase. The latter enzyme is also known as LuxS enzyme or AI-2 synthase.
***The products of the reaction carried out by the LuxS enzyme are homocysteine and DPD, which spontaneously forms the AI-2 group of compounds. ***
It was noted that the LuxS gene was not consistent in its location among chromosomes, but in one species (Borrelia burgdorferi), LuxS was found to be at the terminal position of a three gene sequence. Based on this, it was thought that LuxS might work in coordination with the two genes preceding it. These genes, metK and pfs, are known to be activated in the production of Sadenosylmethionine (SAM).
SAM is used to methylate other molecules and subsequently forms S-adenosylhomocysteine (SAH).
SAH prevents the use of SAM as a methylating agent, which is critical for several bacterial functions.
The pfs gene then converts SAH to SRH, which is then further metabolized into DPD and homocysteine, as mentioned 4 above. The homocysteine can then be methylated to form methionine, which can be used to form SAM. SAM then undergoes a decarboxylation reaction to form methylthioadenosine (MTA), which reacts further with pfs to form methylthioribose (MTR). Schauder and Bassler figured that based on their genomic reasoning,
LuxS could be part of the SAM to DPD series or part of the SAM to MTR reactions since metK and pfs were used in those pathways."
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