
Enzyme pathway in human gut microbiome that converts A to universal O type blood - occamschainsaw
https://naturemicrobiologycommunity.nature.com/users/261113-peter-rahfeld/posts/49635-an-enzymatic-pathway-in-the-human-gut-microbiome-that-converts-a-to-universal-o-type-blood
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canada_dry
> "Blood types are differentiated by the kinds of sugar found on the surface
> of red blood cells. Type O has no sugars. Scientists had realized that some
> (gut) enzymes can remove the sugars from A, B and AB blood cells, turning
> them into Type O"

A superbly concise overview taken from another news article.

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hirenj
The whole ABO system really hints at just how tricky prediction of activity
from amino acid sequence is.

The transferase that puts the A (GalNAc) or B (Galactose) sugar on switches
specificity at the slightest hint of a sequence variation.

Look at the two enzymes found in this paper - one was classified as a CBM
(i.e. only that it bound sugars) and the other in a family that primarily
removes galactose.

As an aside, you have to appreciate this genomic arrangement where the
bacteria are helpful enough to put all the genes needed to do one job (in this
case break down blood antigen) in one place. That way, if you know what one
thing does, you can jump to conclusions about what the others do (e.g. see a
recent paper by Crouch et al).

Final point - if you are wondering where the hell we pick up antibodies to the
different blood type antigens so early, if I remember correctly, it's because
we develop antibodies to bacteria that ALSO have the blood type antigens.

Glycobiology is insanely cool.

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apathy
Posts like yours are the reason I come here. Great stuff. And yes glycoPTMs
are insane.

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TeMPOraL
Full paper: [http://sci-
hub.se/https://doi.org/10.1038/s41564-019-0469-7](http://sci-
hub.se/https://doi.org/10.1038/s41564-019-0469-7).

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mabbo
I'm not very strong on biology, but does this mean, potentially, all blood can
be converted to universal donor blood? That would be truly revolutionary.

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est31
The discovery only touches the ABO group system. While the ABO group system is
the most important one, there are over 36 blood group systems. The Rh blood
group system is important, too: If a Rh(D) negative person gets Rh(D) positive
blood for the first time, it works but they can develop antibodies for it and
if they get such blood a second time, they can get major issues.

In fact, there are more people (and thus potential donors) with type O blood
than there are people with Rh negative blood.

Conversion of type A and B to type O blood is a key step, but it alone doesn't
enable creation of fully universal donor blood (yet).

[1]:
[https://en.wikipedia.org/wiki/Human_blood_group_systems](https://en.wikipedia.org/wiki/Human_blood_group_systems)

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JamesBarney
How much more valuable is O- blood donation than your typical donation?

Curious because some writers suggest it's probably better to work and donate
the proceeds than take the time to donate blood but they didn't go
specifically into my blood type(O-).

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pkaye
O- blood is the universal donor type. Used when blood type is unknown or lack
time to determine like trauma injury. About 7% of the population has this
blood type. If the donor is CMV negative their is even more critical for
immune deficient patients. O- donors can only accept O- blood so it is
important they keep donating to give to other O- patients.

O+ is second best assuming recipient is RH+. O+ is the most common in the
population.

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magduf
>O- donors can only accept O- blood so it is important they keep donating to
give to other O- patients.

Actually, this isn't quite true, according to what I've read. When an O-
person needs blood, they usually give him O+ blood, not O-, because they want
to preserve it (and because they may not know the patient's blood type). The
first time this happens, it's no big deal, but then the Rh- recipient develops
antibodies to the Rh factor. So the next time the O- person gets a
transfusion, they probably die.

I'm an O- person, so I wasn't too thrilled to read this. Luckily I haven't
received any transfusions yet, so I have one free "life"; after that, it's
game-over.

I hope this new research works out.

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pkaye
If they don't know the patients blood type would they check for the Rh
antibodies before using O+ blood?

Some other interesting stuff. I'm on a kidney transplant list. When I was
evaluated, they had me repeat the blood sample draw for blood type twice by
two different people. They want to make sure there is no errors in
classifications. Another thing is those of us with O blood type have to wait
much longer for kidney transplants because we are universal donors for organs
also.

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magduf
>Another thing is those of us with O blood type have to wait much longer for
kidney transplants because we are universal donors for organs also.

It's two things: we're universal donors, but non-universal receivers. We can
give blood to anyone (Rh factor is an extra complication here), but we can
only receive O blood, not any other type, so we're really screwed when we need
something. Us O- people are even worse.

>If they don't know the patients blood type would they check for the Rh
antibodies before using O+ blood?

In a trauma case, they probably don't have time to type your blood at all, so
they just give you O+. There's lots of O+ available, but not much O-. Rh-
people could have a real problem if they've already had an Rh+ transfusion,
but oh well...

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300bps
Red Cross has an amazingly informative site on blood type:

[https://www.redcrossblood.org/donate-blood/blood-
types.html](https://www.redcrossblood.org/donate-blood/blood-types.html)

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oedmarap
Great timing of this article given that tomorrow (Jun 14) is World Blood Donor
Day.

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anigbrowl
Microbiology is wild. I don't think I'd have the patience to work in the field
but it's like an endless number of sequels to Fantastic Voyage.

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sthgrau
I wonder if this is to allow safe digestion/absorption of blood types that
might otherwise cause rejection problems.

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hirenj
It's likely there for either bacterial warfare, or degradation/metabolism of
the mucus layer in the gut (or both).

