7 ms·

Enzyme pathway in human gut microbiome that converts A to universal O type blood

150 points by occamschainsaw 7y ago

TeMPOraL 7y ago
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.
canada_dry 7y ago
> "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.
mabbo 7y ago
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.
- est31 7y ago
  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
  - rscho 7y ago
    It would still massively increase emergency storage, though. Just that would be a major management improvement!
  - JamesBarney 7y ago
    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-).
    - pkaye 7y ago
      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.
      - magduf 7y ago
        >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.
        rscho 7y ago
        Can be true if local shortage. Usually not true, as we'll do everything we can to respect the major antigens.
oedmarap 7y ago
Great timing of this article given that tomorrow (Jun 14) is World Blood Donor Day.
300bps 7y ago
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
sthgrau 7y ago
I wonder if this is to allow safe digestion/absorption of blood types that might otherwise cause rejection problems.
- hirenj 7y ago
  It's likely there for either bacterial warfare, or degradation/metabolism of the mucus layer in the gut (or both).
hirenj 7y ago
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.
- apathy 7y ago
  Posts like yours are the reason I come here. Great stuff. And yes glycoPTMs are insane.
anigbrowl 7y ago
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.

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.

canada_dry 7y ago

> "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.

mabbo 7y ago

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.

est31 7y ago
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
- rscho 7y ago
  It would still massively increase emergency storage, though. Just that would be a major management improvement!
- JamesBarney 7y ago
  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-).
  - pkaye 7y ago
    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.
    - magduf 7y ago
      >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.
      - rscho 7y ago
        Can be true if local shortage. Usually not true, as we'll do everything we can to respect the major antigens.

oedmarap 7y ago

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

300bps 7y ago

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

sthgrau 7y ago

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

hirenj 7y ago
It's likely there for either bacterial warfare, or degradation/metabolism of the mucus layer in the gut (or both).

hirenj 7y ago

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.

apathy 7y ago
Posts like yours are the reason I come here. Great stuff. And yes glycoPTMs are insane.

anigbrowl 7y ago

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.