From Clostridium thermoaceticum to Moorella thermoacetica:
By Viewing the Old, We Learn the New
1
Daniel
Steven L.
and Harold L.
2
Drake
Department of Biological Sciences, Eastern Illinois University, Charleston, Illinois 61920, USA1 and
Department of Ecological Microbiology, University of Bayreuth, D-95440 Bayreuth, Germany2
C6H12O6
Glucose
Methyl Branch
A
CO2
CO2
2 e-
Formate Dehydrogenase
2 ATPSLP
HCOOH
4 [e-]
Glycolysis
Carbonyl Branch
ATP
Formyl-THF Synthetase
Acetyl-CoA
Synthase
ADP + Pi
[CHO]-THF+
2 Pyruvate
H+
Methenyl-THF
Cyclohydrolase
2 CO2
B
4 [e-]
2 Acetyl-CoA
2 Acetylphosphate
8
[e-]
2 e-
Methylene-THF
Dehydrogenase
[CH2]-THF
2 e-
Methylene-THF
Reductase
[CH3]-THF
Acetyl-CoA
Pathway
Methyltransferase
[CH3]-[Co-Protein]
2 ATPSLP
2 CH3COOH
2 e-
[CH]-THF
Harland G. Wood
2 CO2
H2O
[CO]
Acetyl-CoA
Synthase
HSCoA
CH3COOH
Phosphotransacetylase
=
O
Homoacetogenic conversion of glucose
to acetate by C. thermoaceticum
Acetyl-CoA
C
Anabolism
CH3COO-PO32-
ADP
Acetate Kinase
ATP
Lars G. Ljungdahl
Thanks Lars!
CH3C-SCoA
Pi
Clostridium thermoaceticum ATCC 39073 (A) and the two
biochemists (B, C) who were primarily responsible for resolving the
acetyl-CoA or Wood-Ljungdahl pathway in C. thermoaceticum
Assimilation Into
Cellular Carbon
CH3COOH
The acetyl-CoA or Wood-Ljungdahl pathway
as resolved from C. thermoaceticum
A Few of the Gems in Clostridium thermoaceticum’s Treasure Chest
Cellular and metabolic properties of M. thermoacetica
Property
Classification
Habitat
Colony morphology
Cell
morphology
typical size
arrangement
Gram reaction
G + C content (mol %)
Spore
shape
location
D value @ 121ºC
Flagellum
flagellation pattern
motility
Nutritional requirement
Temperature (ºC)
optimum
range
pH
optimum
range
Electron donora
sugars
gases
alcohols
organic acids
Electron acceptorb
C-based
N-based
S-based
Metabolic transformationc
M. thermoacetica
Cytoplasmic
Side
H2
Low G + C, Gram-positive bacteria,
Clostridium, Cluster VI
Bacteria, Firmicutes, Clostridia,
Thermoanaerobacteriales,
Thermoanaerobacteriaceae,
Moorella group, Moorella
2H+
Soils
Circular, smooth, opaque, beige
nNa+
Rod-shaped
0.4 x 2.8 µm
Single, pairs, and chains
+
54
[2H]
[CH2]-THF
X
Membranous
Cytochrome b
nH+
T
S
2 CO2
[e- ]
Na+/H+
Antiporter
Acetyl-CoA
Pathway
nH+
2 e-
OCH3
Nitrate
Block
Site 2
Methyl
By-Pass
Carbonyl
By-Pass
CO
OH
[CH3]-[Co-Protein]
[CO]
Acetyl-CoA Synthase
ATPase
- OH
2 e-
(THF)
Acetate
3 CH3-THF
CH3COOH
Cell Carbon
Scheme illustrating where the acetyl-CoA
pathway is blocked when nitrate is dissimilated
to ammonium by M. thermoacetica
- OH
CH3-THF
3 CO 2
When nitrate is present,
carbon flows towards cell
carbon when nitrate block
is by-passed with methoxyl
groups of aromatic
compounds and CO.
Acetyl-CoA
Carbon flows primarily
towards acetate when
nitrate is not present.
Mechanisms for the formation of a proton gradient
and the chemiosmotic conservation of energy by M.
thermoacetica
3
?
Nitrate
Block
[CH3]-THF Site 1
Membrane
Peritrichous
Nicotinic acid and trace metals
(e.g., Ni, Se, Zn, Mo, W, Co, Fe)
CO2
H2ase
ATP
Spherical
Subterminal, bulged sporangium
83-111 min
CO2
4 e-
ADP + Pi
nH+
Carbonyl
Branch
XH2
E
nH+
Methyl
Branch
Commensal Interaction and Consumption Of O2
55-60
45-65
3
- OCH3
3 THF
THF
6 e-
Glucose, fructose, xylose
H2, CO
Methanol, ethanol, n-propanol,
n-butanol
Formate, oxalate, glyoxylate,
glycolate, pyruvate, lactate
O2
ATP
3 [CO]
CO 2
H2 O
3 Acetyl-CoA
2 Cysteine
Glutamate
5-Aminolevulinic acid
2,4,6-Trinitrotoluene
Hydroxyl-amino-nitrotoluenes
CCl4
CH2Cl2 + CH3Cl
O2 + 4[H]
2 H 2O
H2O2 + XH2
X + 2 H2O
CdCl2 + cysteine
CdS
Inorganic pyrophosphate
inorganic phosphate
X
Fermentative
Microaerophile
Acetate
Obligate
Anaerobe
3 Acetylphosphate
Oxidative
Stress
3 ATP
3 Acetate
Hypothetical routes by which O-methyl groups from methoxylated
aromatic compounds can be utilized by M. thermoacetica
Reductive
Detoxification
eH2 O
Cystine
Moorella
thermoacetica
Oligosaccharides
O2
CO2, carboxyl groups of aromatics
nitrate, nitrite
thiosulfate, dimethylsulfoxide
Thermicanus
aegyptius
HCOOH
3 CH 3-[Co-Protein]
6.8
5.7- 7.7
- OCH3
Metabolic Switch To
Nitrate Dissimilation
e-
H2O2 O2.e-
CO2
NO3-
Acetate
NH4+
e-
H2O H2O2
Mechanisms by which M. thermoacetica
copes with O2 and oxidative stress
All material used with
permission from:
A. M. thermoacetica PT1 (DSM 12993) obtained from Kansas prairie soil.
B. Lanes 2-7 are protein profiles of different strains of M. thermoacetica obtained
from either Kansas soil or Egyptian soil; cells were cultivated on fructose. Lanes 1
and 8 are molecular weight standards. All isolates have nearly identical metabolic
capabilities to M. thermoacetica ATCC 39073 and grow chemolithoautotrophically
at the expense of H2-CO2 or CO-CO2.
Drake, H.L, & S. L. Daniel.
2004.
Physiology of the
thermophilic acetogen
Moorella thermoacetica.
Research in Microbiology
155:869-883.