Ultrastructure and pyruvate formate-lyase radical quenching property of the multienzymic AdhE protein of Escherichia coli.
J Biol Chem
; 267(25): 18073-9, 1992 Sep 05.
Article
en En
| MEDLINE
| ID: mdl-1325457
ABSTRACT
The AdhE protein of Escherichia coli is a homopolymer of 96-kDa subunits harboring three Fe(2+)-dependent catalytic functions acetaldehyde-CoA dehydrogenase, alcohol dehydrogenase, and pyruvate formatelyase (PFL) deactivase. By negative staining electron microscopy, we determined a helical assembly of 20-60 subunits into rods of 45-120 nm in length. The subunit packing is widened along the helix axis when Fe2+ and NAD are present. Chymotrypsin dissects the AdhE polypeptide between Phe762 and Ser763, thereby retaining the alcohol dehydrogenase activity on the NH2-terminal core, but destroying all other activities. PFL deactivation, i.e. quenching of the glycyl radical in PFL by the AdhE protein, was examined with respect to cofactor involvements (Fe2+, NAD, and CoA). This process is coupled to NAD reduction and requires the intact CoA sulfhydryl group. Pyruvate and NADH are inhibitors that affect the steady-state level of the radical form of PFL in a reconstituted interconversion cycle. Studies of cell cultures found that PFL deactivation in situ is initiated at redox potentials of greater than or equal to +100 mV. Our results provide insights into the structure/function organization of the AdhE multienzyme and give a rationale for how its PFL radical quenching activity may be suppressed in situ to enable effective glucose fermentation.
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Colección:
01-internacional
Base de datos:
MEDLINE
Contexto en salud:
3_ND
Problema de salud:
3_neglected_diseases
/
3_zoonosis
Asunto principal:
Acetiltransferasas
/
Alcohol Deshidrogenasa
/
Aldehído Oxidorreductasas
/
Escherichia coli
/
Complejos Multienzimáticos
Idioma:
En
Revista:
J Biol Chem
Año:
1992
Tipo del documento:
Article