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Huh! Biochemistry major here... So I guess that the bacteria just rarely uses Sulphur-Sulphur (thiol) bonds in it's proteins, since Arsenic has a high affinit

Huh! Biochemistry major here... So I guess that the bacteria just rarely uses Sulphur-Sulphur (thiol) bonds in it's proteins, since Arsenic has a high affinity for it (and that's what causes arsenic toxicity in everything else). http://en.wikipedia.org/wiki/Arsenic#Biochemical_basis_of_arsenic_toxicity http://en.wikipedia.org/wiki/Arsenic#Biochemical_basis_of_ar... "suggesting the possibility of a biochemistry very different from the one we know" Seems like a bit of an exaggeration, but news will be news. Thiols are important for the structure & enzymatic activity, but this bacteria is proof that there are ways around it. Besides that difference, I'm guessing they're the same.

jaysonelliot 16y ago
You don't think that the discovery of the first organism to use a different element than phosphorous is a big deal? Cynicism is cool and all that, but this sure sounds like big news to me.
- sandipc 16y ago
  it's a really big deal... provided the arsenic is actually incorporated into nucleic acids, and the bacteria aren't just surviving on background levels of phosphate. it will be interesting to read the original paper when it comes out in Science later today, and not just accounts of the paper from other sources
- deleted 16y ago
  [deleted]
- dnautics 16y ago
  *you don't think the discovery of the first organism to use a different element than sulfur was a big deal? Oh wait, we all do it. http://en.wikipedia.org/wiki/Selenocysteine http://en.wikipedia.org/wiki/Selenocysteine
- dotBen 16y ago
  it would be a much bigger deal if that element was a replacement for carbon :P
paraschopra 16y ago
I'm sure DNA physical structure (angles, bends, etc.) with Arsenic instead of Phosphorous won't be exactly same. Arsenic has same tetrahedral structure as Phosphorous but the atom is sure bigger in size and at DNA scales, size would play a large role in determining shape of molecule. I'm sure you realize that physical interactions play a great role in a cell.
- dnautics 16y ago
  you would think, but there's also: http://en.wikipedia.org/wiki/XDNA http://en.wikipedia.org/wiki/XDNA It's true that the subtle loss of a hydroxyl group leads to all sorts of differences between RNA and DNA (RNA likes to be single-stranded more than DNA does) but there's TNAs (unfortunate acronyms) and PNAs (not to be confused with PNAS) and other things that basically work and look like DNA with fairly un-subtle changes. Furthermore, Arsenic really isn't THAT much bigger than Phosphorus (vdw radius 1.85 vs 1.80; covalent radius 1.19 vs 1.06).
crocowhile 16y ago
Yes, beside the fact that they found a way to change the structure of their DNA, RNA, and a few hundreds enzymes involved in energy metabolism they are the same... This is so huge that my money go into a mistake: I bet these bacteria just found a way to either get rid of arsenic or to neutralize its allosteric toxicity by maskerading or something. The paper is not out yet so I cannot give my opinon on the experimental data but from what I read there is no evidence that DNA actually contains arsenic and until that arrives I believe it's a red herring.
- mechanical_fish 16y ago
  It does seem overwhelmingly likely to be a mistake. But an exciting one! Biochemistry sports fans like myself will watch with interest. EDIT: Hey, my upvote voted you down by mistake! Somebody upvote the parent, please.
- roadnottaken 16y ago
  "from what I read there is no evidence that DNA actually contains arsenic" FTFA: "When the researchers added radio-labelled arsenate to the solution to track its distribution, they found that arsenic was present in the bacterium's proteins, lipids and metabolites such as ATP and glucose, as well as in the nucleic acids that made up its DNA and RNA. The amounts of arsenate detected were similar to those expected of phosphate in normal cell biochemistry, suggesting that the compound was being used in the same way by the cell. The team used two different mass-spectrometry techniques to confirm that the bacterium's DNA contained arsenic... Analysis with laser-like X-rays from a synchrotron particle accelerator indicated that this arsenic took the form of arsenate, and made bonds with carbon and oxygen in much the same way as phosphate." It sounds like there IS some evidence...
  - crocowhile 16y ago
    The author themselves are tyring to explain to you that "Our data are strongly suggestive of arsenic replacing phosphorus". Where suggestive =!= evidence. Plus, read the paragraph "A world of possibilities" to see why so(FTFA). There is no evidence. There are results that are compatible with that and other scenarios. Science is not so easy as you wish it was.

jaysonelliot 16y ago

You don't think that the discovery of the first organism to use a different element than phosphorous is a big deal? Cynicism is cool and all that, but this sure sounds like big news to me.

sandipc 16y ago
it's a really big deal... provided the arsenic is actually incorporated into nucleic acids, and the bacteria aren't just surviving on background levels of phosphate. it will be interesting to read the original paper when it comes out in Science later today, and not just accounts of the paper from other sources
deleted 16y ago
[deleted]
dnautics 16y ago
*you don't think the discovery of the first organism to use a different element than sulfur was a big deal? Oh wait, we all do it. http://en.wikipedia.org/wiki/Selenocysteine http://en.wikipedia.org/wiki/Selenocysteine
dotBen 16y ago
it would be a much bigger deal if that element was a replacement for carbon :P

paraschopra 16y ago

I'm sure DNA physical structure (angles, bends, etc.) with Arsenic instead of Phosphorous won't be exactly same. Arsenic has same tetrahedral structure as Phosphorous but the atom is sure bigger in size and at DNA scales, size would play a large role in determining shape of molecule. I'm sure you realize that physical interactions play a great role in a cell.

dnautics 16y ago
you would think, but there's also: http://en.wikipedia.org/wiki/XDNA http://en.wikipedia.org/wiki/XDNA It's true that the subtle loss of a hydroxyl group leads to all sorts of differences between RNA and DNA (RNA likes to be single-stranded more than DNA does) but there's TNAs (unfortunate acronyms) and PNAs (not to be confused with PNAS) and other things that basically work and look like DNA with fairly un-subtle changes. Furthermore, Arsenic really isn't THAT much bigger than Phosphorus (vdw radius 1.85 vs 1.80; covalent radius 1.19 vs 1.06).

crocowhile 16y ago

Yes, beside the fact that they found a way to change the structure of their DNA, RNA, and a few hundreds enzymes involved in energy metabolism they are the same... This is so huge that my money go into a mistake: I bet these bacteria just found a way to either get rid of arsenic or to neutralize its allosteric toxicity by maskerading or something. The paper is not out yet so I cannot give my opinon on the experimental data but from what I read there is no evidence that DNA actually contains arsenic and until that arrives I believe it's a red herring.

mechanical_fish 16y ago
It does seem overwhelmingly likely to be a mistake. But an exciting one! Biochemistry sports fans like myself will watch with interest. EDIT: Hey, my upvote voted you down by mistake! Somebody upvote the parent, please.
roadnottaken 16y ago
"from what I read there is no evidence that DNA actually contains arsenic" FTFA: "When the researchers added radio-labelled arsenate to the solution to track its distribution, they found that arsenic was present in the bacterium's proteins, lipids and metabolites such as ATP and glucose, as well as in the nucleic acids that made up its DNA and RNA. The amounts of arsenate detected were similar to those expected of phosphate in normal cell biochemistry, suggesting that the compound was being used in the same way by the cell. The team used two different mass-spectrometry techniques to confirm that the bacterium's DNA contained arsenic... Analysis with laser-like X-rays from a synchrotron particle accelerator indicated that this arsenic took the form of arsenate, and made bonds with carbon and oxygen in much the same way as phosphate." It sounds like there IS some evidence...
- crocowhile 16y ago
  The author themselves are tyring to explain to you that "Our data are strongly suggestive of arsenic replacing phosphorus". Where suggestive =!= evidence. Plus, read the paragraph "A world of possibilities" to see why so(FTFA). There is no evidence. There are results that are compatible with that and other scenarios. Science is not so easy as you wish it was.