Rhodospirillum rubrum

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Rhodospirillum rubrum
Botony Exam 1 004.JPG
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Alphaproteobacteria
Order: Rhodospirillales
Family: Rhodospirillaceae
Genus: Rhodospirillum
Species: R. rubrum
Binomial name
Rhodospirillum rubrum
(Esmarch 1887) Molisch 1907[1]

Rhodospirillum rubrum (R. rubrum) is a Gram-negative, pink-coloured Proteobacterium, with a size of 800 to 1000 nanometers.

It is a facultative anaerobe, it can therefore use alcoholic fermentation under low oxygen conditions or use aerobic respiration in aerobic conditions. Under aerobic growth photosynthesis is genetically suppressed and R. rubrum is then colorless. After the exhaustion of oxygen, R. rubrum immediately starts the production of photosynthesis apparatus including membrane proteins, bacteriochlorophylls and carotenoids, i.e. the bacterium becomes photosynthesis active. The repression mechanism for the photosynthesis is poorly understood. The photosynthesis of R. rubrum differs from that of plants as it possesses not chlorophyll a, but bacteriochlorophylls. While bacteriochlorophyll an absorbs light having a maximum wavelength of 800 to 925 nm, chlorophyll absorbs light having a maximum wavelength of 660 to 680 nm. R. rubrum is a spiral-shaped bacterium (spirillum, plural form: spirilla).

R. rubrum is also a nitrogen fixing bacterium, i.e., it can express and regulate nitrogenase, a protein complex that can catalyse the conversion of atmospheric dinitrogen into ammonia. When the bacteria are exposed to ammonia, darkness, and phenazine methosulfate, nitrogen fixation stops.[2] Due to this important property, R. rubrum has been the test subject of many different groups, so as to understand the complex regulatory schemes required for this reaction to occur (,[3][4][5][6] among others). It was in R. rubrum that, for the first time, post-translational regulation of nitrogenase was demonstrated. Nitrogenase is modified by an ADP-ribosylation in the arginine residue 101 (Arg101)[7] in response to the so-called "switch-off" effectors - glutamine or ammonia - and darkness.[8]

R. rubrum has several potential uses in biotechnology:

References[edit]

  1. ^ Parte, A.C. "Rhodospirillum". www.bacterio.net. 
  2. ^ Kanemoto, R. H.; Ludden, P. W. (1984-05-01). "Effect of ammonia, darkness, and phenazine methosulfate on whole-cell nitrogenase activity and Fe protein modification in Rhodospirillum rubrum". Journal of Bacteriology. 158 (2): 713–720. ISSN 0021-9193. PMC 215488Freely accessible. PMID 6427184. 
  3. ^ Teixeira PF, Jonsson A, Frank M, Wang H, Nordlund S (2008). "Interaction of the signal transduction protein GlnJ with the cellular targets AmtB1, GlnE and GlnD in Rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the ADP/ATP ratio". Microbiology. 154 (Pt8): 2336–47. PMID 18667566. doi:10.1099/mic.0.2008/017533-0. 
  4. ^ Selao TT, Nordlund S, Norén A (2008). "Comparative proteomic studies in Rhodospirillum rubrum grown under different nitrogen conditions". J Proteome Res. 7 (8): 3267–75. PMID 18570453. doi:10.1021/pr700771u. 
  5. ^ Wolfe DM, Zhang Y, Roberts GP (2007). "Specificity and Regulation of Interaction between the PII and AmtB1 Proteins in Rhodospirillum rubrum". J Bacteriol. 189 (19): 6861–6869. PMC 2045211Freely accessible. PMID 17644595. doi:10.1128/JB.00759-07. 
  6. ^ Jonsson A, Teixeira PF, Nordlund S (2007). "The activity of adenylyltransferase in Rhodospirillum rubrum is only affected by alpha-ketoglutarate and unmodified PII proteins, but not by glutamine, in vitro". FEBS J. 274 (10): 2449–60. PMID 17419734. doi:10.1111/j.1742-4658.2007.05778.x. 
  7. ^ Pope MR, Murrell SA, Ludden PW (1985). "Covalent modification of the iron protein of nitrogenase from Rhodospirillum rubrum by adenosine diphosphoribosylation of a specific arginine residue". Proc Natl Acad Sci U S A. 82 (10): 3173–7. PMC 397737Freely accessible. PMID 3923473. doi:10.1073/pnas.82.10.3173. 
  8. ^ Neilson AH, Nordlund S (1975). "Regulation of nitrogenase synthesis in intact cells of Rhodospirillum rubrum: inactivation of nitrogen fixation by ammonia, L-glutamine and L-asparagine". J Gen Microbiol. 91 (1): 53–62. PMID 811763. doi:10.1099/00221287-91-1-53. 

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