Characterization of hydrogenosomes and their role in glucose metabolism of Neocallimastix sp. L2.
In the anaerobic fungus Neocallimastix sp. L2 fermentation of glucose proceeds via the Embden-Meyerhof-Parnas pathway. Enzyme activities leading to the formation of succinate, lactate, ethanol, and formate are associated with the cytoplasmic fraction. The enzymes 'malic enzyme,' NAD(P)H:ferredoxin oxidoreductase, pyruvate:ferredoxin oxidoreductase, hydrogenase, acetate:succinate CoA transferase and succinate thiokinase leading to the formation of H2,CO2, acetate, and ATP are localized in microbodies. Thus, these organelles are identified as hydrogenosomes. In addition, the microbodies contain the O2-scavenging enzymes NADH- and NADPH oxidase, while NAD(P)H peroxidase, catalase, or superoxide dismutase could not be detected. In cell-free extracts from zoospores of Neocallimastix sp. L2 the specific activities of hydrogenosomal enzymes as well as the quantities of these proteins are 2- to 6-fold higher than in mycelium extracts. These findings suggest that hydrogenosomes perform an important role--especially in zoospores--as H2-evolving, ATP-generating and O2-scavenging organelles.
Marvin-Sikkema
F D
FD
Department of Microbiology, University of Groningen, The Netherlands.
Pedro Gomes
T M
TM
Grivet
J P
JP
Gottschal
J C
JC
Prins
R A
RA
D000263:Adenylate Kinase / Q000032:analysis; D000818:Animals; D002161:Camelids, New World / Q000382:microbiology*; D002499:Centrifugation, Density Gradient; D008411:Chytridiomycota / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D015256:Coenzyme A-Transferases / Q000032:analysis; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D006593:Hexokinase / Q000032:analysis; D006864:Hydrogenase / Q000032:analysis; D007658:Ketone Oxidoreductases / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008291:Malate Dehydrogenase / Q000032:analysis; D008830:Microbodies / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010088:Oxidoreductases / Q000032:analysis; D010732:Phosphofructokinase-1 / Q000032:analysis; D010751:Phosphopyruvate Hydratase / Q000032:analysis; D050743:Pyruvate Synthase; D013053:Spectrophotometry; D013389:Succinate-CoA Ligases / Q000032:analysis
D010088:Oxidoreductases; D008291:Malate Dehydrogenase; C034544:D-malate dehydrogenase (decarboxylating); D006864:Hydrogenase; C028878:ferredoxin-NAD+ reductase; D007658:Ketone Oxidoreductases; D050743:Pyruvate Synthase; D006593:Hexokinase; D010732:Phosphofructokinase-1; D000263:Adenylate Kinase; D015256:Coenzyme A-Transferases; D010751:Phosphopyruvate Hydratase; D013389:Succinate-CoA Ligases; D005947:Glucose