Elucidation of the metabolic fate of glucose in the filamentous fungus Trichoderma reesei using expressed sequence tag (EST) analysis and cDNA microarrays.
Despite the intense interest in the metabolic regulation and evolution of the ATP-producing pathways, the long standing question of why most multicellular microorganisms metabolize glucose by respiration rather than fermentation remains unanswered. One such microorganism is the cellulolytic fungus Trichoderma reesei (Hypocrea jecorina). Using EST analysis and cDNA microarrays, we find that in T. reesei expression of the genes encoding the enzymes of the tricarboxylic acid cycle and the proteins of the electron transport chain is programmed in a way that favors the oxidation of pyruvate via the tricarboxylic acid cycle rather than its reduction to ethanol by fermentation. Moreover, the results indicate that acetaldehyde may be channeled into acetate rather than ethanol, thus preventing the regeneration of NAD(+), a pivotal product required for anaerobic metabolism. The studies also point out that the regulatory machinery controlled by glucose was most probably the target of evolutionary pressure that directed the flow of metabolites into respiratory metabolism rather than fermentation. This finding has significant implications for the development of metabolically engineered cellulolytic microorganisms for fuel production from cellulose biomass.
Chambergo
Felipe S
FS
Department of Biochemistry, Institute of Chemistry, University of São Paulo, Avenida Prof. Lineu Prestes 748, São Paulo SP 05508-900, Brazil.
Bonaccorsi
Eric D
ED
Ferreira
Ari J S
AJ
Ramos
Augusto S P
AS
Ferreira Júnior
José Ribamar
JR
Abrahão-Neto
José
J
Farah
João P Simon
JP
El-Dorry
Hamza
H
D000085:Acetates / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002952:Citric Acid Cycle; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000378:metabolism; D020224:Expressed Sequence Tags; D015723:Gene Library; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010100:Oxygen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014242:Trichoderma / Q000378:metabolism*
D000085:Acetates; D018076:DNA, Complementary; D012333:RNA, Messenger; D009243:NAD; D000431:Ethanol; D005947:Glucose; D010100:Oxygen