Wednesday, April 25, 2012

2 Strange But True Facts About Spirochetes

Image: Kilauea Volcano
by Brian Snelson

I have a few strange but true facts about spirochetes to share which you may not know. A few are ones I have shared here before  - but most are not something about which I've already written. What you read here today may surprise you...




  • Many people call Borrelia burgdorferi spirochetes Gram negative bacteria. However, Borrelia burgdorferi are not Gram-negative bacteria even if a Gram negative stain works on them:

    "Borrelia were thought to be Gram negative because of their double membrane structure, but genetic analysis places them - along with other spirochetes - into a separate eubacterial phylum. Ultrastructural molecular and biochemical studies have emphasized the wide taxonomic gap between spirochetes and Gram-negative bacteria."

    - From "The Genus Borrelia" by Melissa Caimano. Prokaryotes (2006) 7:235-293.
  • Unlike Leptospira and Brachyspira, spirochetes in the Borrelia and Treponema genera appear to have acquired Phenylalanyl-tRNA synthetase (PheRS)  genes from Archaea through horizontal gene transfer. [1] Borrelia and Treponema have Archaea genes.
  • Somewhere along the line, an ancient Spirochaeta relative picked up genes from Archaea's order, Thermococcales. Borrelia and Treponema have close affinities with Thermococcus and Pyrococcus (not depicted on tree).[1]
  •  The fascinating thing about this genetic relationship is that these genes come from organisms which are extremely thermophilic organisms. They are extremophiles - which means they can live in extreme environments. Thermophilic extremophiles thrive in hot environments such as volcanic vents and hot springs. That genes from extremophiles would end up in mesophilic organisms which thrive in lower temperatures - such as in mammalian and acarian hosts - seems surprising. The highest temperature Borrelia garinii can still grow in is around 41-42 C. That's not anywhere near the high temperatures in which one finds Archaean Thermococcales (often over 60 C, sometimes as high as 100 C).
  • This all does seem really weird. But the reason why it isn't too far fetched to see genes from extremely thermophilic organisms in moderately warm Borrelia and Treponema is more easily understood once you know more about the wide diversity found within the genus Spirochaeta in general. A number of Spirochaeta species live in extreme environments and not just in humans, animals, or ticks. For example:
    • S. halophila lives in a high salinity pond on the Sinai shore.[2]
    • S. thermophila lives in marine hot springs in New Zealand and Russia.[3]
    • S. americana lives in alkaline, hypersaline Mono Lake in California.[4]
Champagne PoolWai-O-Tapu, near Rotorua, New Zealand by Christian Mehlf├╝hrer

  • When looking at a phylogenetic tree, Spirochaeta is at the base of the tree and Borrelia and Treponema branch off later. Based on this, the best assessment one can make about the gene transfer from Archaea to Spirochaeta is that the most recent common ancestor of Spirochaeta, Borrelia, and Treponema had to have been very similar to thermophilic Spirochaeta.
  • My running joke on this is to imagine a pile of thermophilic Archaea and thermophilic Spirochaeta hanging out around a hot spring together, laughing, joking, and flirting. Before you know it, horizontal gene transfer occurs, and a new form of spirochete is born. (This would make for a good Far Side comic, I just know it.)
  • As if having Borrelia acquire Archaea genes wasn't interesting enough, it's been thought that ProS prolyl-tRNA synthetase (BB402) was acquired from a eurkaryote.

  • Treponema spirochetes have a symbiotic relationship with termites. These spirochetes help termites in breaking down cellulose in wood in the termites' guts. So it isn't just ticks which have a symbiotic relationship with spirochetes - termites have one, too.[1, 5]

  • Borrelia burgdorferi survives on the equivalent of tick antifreeze in the tick's midgut inbetween tick blood feeding cycles. Borrelia burgdorferi prefers glucose when in the tick, but it will feast on glycerol instead. See: http://spirochetesunwound.blogspot.com/2011/10/lyme-disease-spirochete-feasts-on-tick.html
  • Both Borrelia hermsii and Borrelia burgdorferi metabolize chitobiose and N acetyl-glucosamine, a nutrient of these spirochetes and the major constituent of chitin for the exoskeletons of ticks.[6]
  • Borrelia have most of the genes required for the enzymes which make up the mevalonate pathway - a metabolic pathway used by the bacteria for synthesis of isoprenoid precursors. Isoprenoids are very important compounds which are found in over 30,000 products from the three domains of life (Eukaryotes, Prokaryotes, and Archaea). One interesting proposal about how Borrelia has the genes required for these enzymes for this pathway is that they come from the genetic cenancestor - an ancestor which predates the split into the three domains.[7]
     
  • In Act II of Samuel Beckett's play, Waiting For Godot, one character, Estragon, curses at the other, Vladimir, by calling him, "Gonococcus! Spirochete!"
Spirochetes continue to hold surprises and mysteries for us all... both good and bad. Another interesting installment of strange spirochete facts could be posted here - probably not too far in the future.

References:

1) Cheryl P Andam and J Peter Gogarten. Biased gene transfer and its implications for the concept of lineage. Biology Direct 2011, 6:47 doi:10.1186/1745-6150-6-47
2) Greenberg EP, Canale-Parola E: Spirochaeta halophila sp. n., a facultative anaerobe from a high-salinity pond. Arch Microbiol 1976, 110:185-19
3) Aksenova H, Rainey F, Janssen P, Zavarzin G, Morgan H: Spirochaeta thermophila sp. nov., an obligately anaerobic, polysaccharolytic, extremely thermophilic bacterium. Int J Syst Bacteriol 1992, 42:175-177
4) Hoover RB, Pikuta EV, Bej AK, Marsic D, Whitman WB, Tang J, Krader P: Spirochaeta americana sp. nov., a new haloalkaliphilic, obligately anaerobic spirochaete isolated from soda Mono Lake in California. Int J Syst Evol Microbiol 2003, 53:815-821.
5) Droge S, Frohlich J, Radek R, Konig H: Spirochaeta coccoides sp. nov., a novel coccoid spirochete from the hindgut of the termite Neotermes castaneus. Appl Environ Microbiol 2006, 72:392-397.
6) Tilly, K., Elias, A.F., Errett, J., Fischer, E., Iyer, R., Schwartz, I., et al. Genetics and regulation of chitobiose utilization in Borrelia burgdorferi. J Bacteriol 183: 5544–5553.
7) Jonathan Lombard and David Moreira. Origins and Early Evolution of the Mevalonate Pathway of Isoprenoid Biosynthesis in the Three Domains of Life. Mol Biol Evol  2011, 28 (1): 87-99. doi: 10.1093/molbev/msq177 http://mbe.oxfordjournals.org/content/28/1/87.full


2 comments:

  1. Thank you for this wonderful post Camp Other. It gives me hope to know that a human being with an enquiring mind,intelligence,integrity and honesty is helping highlight the known facts, uncertainties and controversies surrounding Lyme disease. The added value is that you cast the net wider and cover immunology, archaea, gene transfer...
    Survival= Adaptation - I'm old enough to remember that was Jacob Bronowski's conclusion about man's successful domination of this planet. But maybe all the time we adapted, other things adapted alongside us - hitch-hikers - opportunists - colonisers. As we colonised, so we were colonised. Maybe this particular plague of tick borne diseases is a response to the general decline in biodiversity, as a result of man's impact on the environment.
    Borrelia isn't the only bacteria that's adapting to change; they all are, but it seems to me that controversy has had a negative effect on progress in clinical research in relation to Lyme disease.
    I attended the 12th ECCMID meeting in London in April (manning the stand for LDA) and hundreds of poster sessions focussed on the issue of persistent bacterial disease generally: Genetic mutation and antibiotic resistance, phenotypic change and antibitoic tolerance, biofilm formation, quorum sensing...
    Do you ever wonder (as I do) how borrelia evolved and survived before there were ticks or animals or people. How does a zoonosis set up shop without a vector or animals??! Surely they must be highly adaptive and opportunistic organisms.....

    ReplyDelete
  2. Hi LymePickle,

    You're welcome. It was fun to put together this post and share some of the weirder things there are to know about spirochetes. The thing is, if one looks at all living things this way, one will find connections they didn't see before for other organisms as well. Evolution is a strange thing, and people try to guess what the nearest relative is of some creature based on appearance, but when you look at their genome it can tell a very different story. Embrace the freaky: Here is a sea slug, Elysia chlorotica, which produces chlorophyll and can live off the sun. Doesn't have to eat a thing in order to survive - just sunbathe. Breatharians, move over.

    So yes, there are interesting genetic combinations out there, and while some may claim they are the result of some mad scientist's conspiracy theory laiden project gone awry, the truth is that nature is often creating more fantastic creatures of its own.

    I have to cast the net wider here when it comes to Spirochetes, I think, and not just out of the coolness factor. I suspect that if we look at their genetics and how they are different, that could lead to new targets for treatment. One target may very well be these genes from Archaea. They might be an Archea's heel, so to speak, and that would be useful.

    So far as it's known, Archaea are not considered to be pathogenic. But maybe that doesn't matter, and if their genes end up in spirochetes, it's what they happen to do in the mix that matters.

    One thing I want to know is where Borrelia gets its outer surface proteins. I was reading a dissertation the other day where it was said that they couldn't find homologous proteins in the database for Borrelia's Osps. And that got me thinking, why is that? And so it got the ball rolling on writing this entry. I still don't have the answer to my question, by the way... But I'm hoping with diligence and talking to those in the field that I will. We'll at least have some more directed speculation, coming from those who are working on phylogenetics and BLAST a lot.

    Even after having suffered from Lyme disease and Babesia and its effects for several years now, I still don't fully understand why there is a controversy. Yes, people have tried to explain it to me - but from a scientific perspective, I would think if something is not completely settled then... well, it's not completely settled. If it's not, then do what you can to help people feel better. Minimize risk as much as you can, but don't let people suffer. Allowing human suffering to continue is unethical.

    You went to the 12th ECCMID? That must have been fascinating. Is the LDA there now? I think we're up to, what, the 22nd or 23rd ECCMID now? I wish I could go.

    I do wonder how Borrelia evolved and survived before there were ticks and mammals. It is an interesting thing to think about, and it was probably an ancient ancestor we're really thinking about and what happened to change its path.

    If you're really interested in this kind of thing, check out this paper - full text available at the link:
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC97324/

    ReplyDelete

You can use <b>bold</b>, <i>italics</i>, and <a href="url">link</a> for links.

The Camp Other Song Of The Month


Why is this posted? Just for fun!

Get this widget

Lyme Disease

Borrelia

Bacteria

Microbiology

Related Posts Plugin for WordPress, Blogger...