MIC 329 The Gram-positive World*. *(Well, really a talk about my favorite Gram (+) organism, Bacillus subtilis ). The changing definition of Bacillus : Any rod-shaped bacterium then Gram-positive rods then Aerobic Gram (+) rods then along came 16S sequences…. Sporosarcina.
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*(Well, really a talk about my favorite Gram (+) organism, Bacillus subtilis)
The changing definition of Bacillus:
Any rod-shaped bacterium
Aerobic Gram (+) rods
then along came 16S sequences…...
Bacillus subtilis differentiation cycle
Solar UV vegetative cells
The spore coat layers protect spores from vegetative cells
solar UV wavelengths
Riesenman and Nicholson. AEM 66: 620. 2000.
Spore pigment offers significant protection vegetative cells
against environmentally-relevant UV wavelengths
Wild-type (+) CuSO4
Wild-type (-) CuSO4
DcotA (+) CuSO4
Hullo, et al. J. Bacteriol. 183: 5426. 2001.
Dipicolinic acid (pyridine-2,6-dicarboxylate) vegetative cells
DPA is especially important for spore vegetative cells
resistance to UV-B radiation
Slieman and Nicholson. AEM 67: 1274. 2001.
Bacillus subtilis vegetative cells differentiation cycle
Saran Wrap is different
A. Filter lid
B. 3x dried spore spots
C. Microscope slide
Appl. Environ. Microbiol.
62: 2221-2227. 1996.
B. subtilis DNA damage(s)? spore DNA
exposed to sunlight
accumulates ss breaks,
ds breaks and cyclobutane
dimers in addition to SP.
0.8% neutral agarose
0.8% alkaline agarose
Summary of DNA DNA damage(s)?
Damage in solar
Appl. Environ. Microbiol. 66:199-205. 2000.
J. Bact. 175:1735.1993. Curr. Micro.34:133.1997.
J.Bact. 176: 3983.1994. MGG 255:587.1997.
J.Bact.177: 4402. 1995. J.Bact. 182:555.2000.
1. SplB dimerizes via a [4Fe-4S] center.
2. Specific binding to SP in DNA.
3. SAM split by electron donation from Fe-S center, producing 5’-adenosyl radical.
4. Radical abstracts proton from C-6 of SP, reverses SP back to 2 T’s.
J.Bact. 180:4879. 1998. PNAS 98: 9038. 2001.
J.Bact. 182: 6412. 2000.
In the laboratory: DNA damage(s)?
Spores are highly UV resistant.
SP is the major DNA damage.
CPD, ss, ds breaks negligible at biol. relevant UV doses.
SP lyase > NER during germination.CONCLUSIONS
Patricia Fajardo Mario Pedraza
Lilian Chooback Roberto Rebeil
Heather Glanzberg Paul Riesenman
Jocelyn Law Tony Slieman
Rachel Mastrapa Yubo Sun
Heather Maughan Yaming Xue