Even though you look more like the Micrococcus who you were named for in 1956, your 16S ribosomal sequences beg to differ and place you closer to Thermus. So we even gave you your own genus in the 80s: Deinococcus and made you the first card-carrying member of i-can-survive-high-amounts-of-radiation club. But that wasn’t enough for you. You wanted to be called “Conan” after some higher eukaryotic barbarian. We say NO! Go find your own pulp-fiction characters. And so as a protest, I assume, you go look all gram-negative with your cell envelope and your outer membranes (I ask you, do you really need 6 layers?) but you stain gram positive … like gram staining isn’t bloody confusing enough. And what is it with you microbes and your need to be in the spotlight? You get your share of attention showered on you, being a POLYextremophile and all. You even get mentioned in Craig Venter’s TED talk. Before you go around telling the world how Craig Venter “optically mapped” you, let me tell you: he didn’t choose you because you are so good at fixing DNA breaks. He wants to USE you. And he will own your ass soon (if he doesn’t already). But whatever, live in your little desiccated reality.
I get it. Your life was hard. You’ve had to deal with desiccation (allegedly). So you rolled in tetracocci and got thick peptidoglycan skins. But your DNA was still just the fragile DNA (thankfully, the phosphorus backboned kind, unlike some others we know) that we all have and desiccation can cause double stranded breaks in DNA. So you decided to go one step further and figure out how to fix broken DNA. And while evolving to protect your DNA from desiccation, you just happened to render yourself also immune to high levels of radiation. Right. Likely story. I don’t mean to steal your thunder or anything, Sir Deinococcus, but the cyanobacterium Chroococcidiopsis can withstand high levels of ionizing radiation too and they live on the underside of quartz stones. In the Atacama desert. AND can photosynthesize. Who’s extreme now, bitch? (Yes Chroococcidiopsis, I know you exist, I’ll get to you too sometime.)
OK, I’ll admit it. Back then, we thought you were so cool. So, we sequenced you and found some 2 large circular chromosomes, some HGT, some strange genes and more mundane genes. We ran gels of your DNA before and after radiation and found that you could indeed fix broken DNA. We even used the (at the time) hot new microarray technology to figure out what genes you were turning on to fix your DNA and found genes of unknown function: ddrA, ddrB, ddrC, ddrD, pprA. And then we tried to characterize the protein products of these genes. And what we ended up with can be summarized in one meaningless sentence: “It is currently difficult to predict which mechanism(s) will be most important in radioresistance, or even whether all of the contributing mechanisms have been discovered.” I guess what I’m trying to say is we got precious little from that academic relationship. We did figure out that just having multiple copies of the genome does not by itself repair the 1000s of double stranded breaks inflicted on your genome with our high power γ-rays. We deduced this from the fact that normal bacteria often have 4 copies in a cell and they can’t fix shit when faced with 10000 Gray. Oh, but don’t worry, we noticed the Manganese(II) you keep around. Maybe it scavenges the reactive oxygen species (ROS) that would otherwise damage vital proteins or maybe it just leads to the condensation of the genome so that the severed genomic pieces stay close to their actual neighbors. We will let you know when we figure it out. Meanwhile, you go on fixing your double stranded breaks in a (partially) Rec-A depended fashion, like all the other run-of-the-mill, ordinary, banal, average conjugating bacteria everywhere.
Lets face it. You’re so 2001, when your genome came out and everyone thought you were the shit. There was even some debate about if you came from outer-space. Frankly, I don’t really care right now, as long as you just go out (or back) into space (we know you can survive there) and promise never to come back or show your brilliant little ionizing-radiation-resistant ass to me ever again. Conjugate you! (Ha! You aren’t fucking resistant to that! Wait, are you?)
- Billi D, Friedmann EI, Hofer KG, Caiola MG, Ocampo-Friedmann R. Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium Chroococcidiopsis. Appl Environ Microbiol. 2000 Apr;66(4):1489-92.
- Cox MM, Battista JR. Deinococcus radiodurans – the consummate survivor. Nat Rev Microbiol. 2005 Nov;3(11):882-92.
- Daly MJ, Gaidamakova EK, Matrosova VY, Kiang JG, Fukumoto R, Lee DY, Wehr NB, Viteri GA, Berlett BS, Levine RL. Small-molecule antioxidant proteome-shields in Deinococcus radiodurans. PLoS One. 2010 Sep 3;5(9):e12570.
- Daly MJ, Gaidamakova EK, Matrosova VY, Vasilenko A, Zhai M, Venkateswaran A, Hess M, Omelchenko MV, Kostandarithes HM, Makarova KS, Wackett LP, Fredrickson JK, Ghosal D. Accumulation of Mn(II) in Deinococcus radiodurans facilitates gamma-radiation resistance. Science. 2004 Nov 5;306(5698):1025-8. Epub 2004 Sep 30.
- Daly MJ, Ouyang L, Fuchs P, Minton KW. In vivo damage and recA-dependent repair of plasmid and chromosomal DNA in the radiation-resistant bacterium Deinococcus radiodurans. J Bacteriol. 1994 Jun;176(12):3508-17.
- Dartnell LR, Hunter SJ, Lovell KV, Coates AJ, Ward JM. Low-temperature ionizing radiation resistance of Deinococcus radiodurans and Antarctic Dry Valley bacteria. Astrobiology. 2010 Sep;10(7):717-32.
- Dean CJ, Feldschreiber P, Lett JT. Repair of x-ray damage to the deoxyribonucleic acid in Micrococcus radiodurans. Nature. 1966 Jan 1;209(5018):49-52.
- Gross L. Paradox resolved? The strange case of the radiation-resistant bacteria. PLoS Biol. 2007 Apr;5(4):e108. Epub 2007 Mar 20.
- Lacap DC, Warren-Rhodes KA, McKay CP, Pointing SB. Cyanobacteria and chloroflexi-dominated hypolithic colonization of quartz at the hyper-arid core of the Atacama Desert, Chile. Extremophiles. 2010 Nov 11. [Epub ahead of print]
- Levin-Zaidman S, Englander J, Shimoni E, Sharma AK, Minton KW, Minsky A. Ringlike structure of the Deinococcus radiodurans genome: a key to radioresistance? Science. 2003 Jan 10;299(5604):254-6.
- Lin J, Qi R, Aston C, Jing J, Anantharaman TS, Mishra B, White O, Daly MJ, Minton KW, Venter JC, Schwartz DC. Whole-genome shotgun optical mapping of Deinococcus radiodurans. Science. 1999 Sep 3;285(5433):1558-62.
- Makarova KS, Aravind L, Wolf YI, Tatusov RL, Minton KW, Koonin EV, Daly MJ. Genome of the extremely radiation-resistant bacterium Deinococcus radiodurans viewed from the perspective of comparative genomics. Microbiol Mol Biol Rev. 2001 Mar;65(1):44-79.
- Pavlov AK, Kalinin VL, Konstantinov AN, Shelegedin VN, Pavlov AA. Was Earth ever infected by martian biota? Clues from radioresistant bacteria. Astrobiology. 2006 Dec;6(6):911-8.
- Repar J, Cvjetan S, Slade D, Radman M, Zahradka D, Zahradka K. RecA protein assures fidelity of DNA repair and genome stability in Deinococcus radiodurans. DNA Repair (Amst). 2010 Nov 10;9(11):1151-61.
- Tanaka M, Earl AM, Howell HA, Park MJ, Eisen JA, Peterson SN, Battista JR. Analysis of Deinococcus radiodurans’s transcriptional response to ionizing radiation and desiccation reveals novel proteins that contribute to extreme radioresistance. Genetics. 2004 Sep;168(1):21-33.