Biochemical characterization of the chlB mutant of E. coli

Conference · Mon Mar 11 04:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5373115

Johnson, J L; Indermauer, L W; Rajagopalan, K V ^[1]

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1. Duke Univ., Durham, NC (United States)

The chlorate resistant mutants of E. coli exhibit a pleiotropic loss of the activities of several molybdoenzymes suggestive of defective molybdenum cofactor synthesis. Indeed, mutants at the chlA and chlE loci have been shown to be deficient in molybdenum cofactor. ChlB mutants, on the other hand, contain high levels of molybdenum cofactor as measured by conversion to the Form A derivative and by reconstitution of the nitrate reductase in the high molecular weight fraction of extracts of the Neurospora crassa nit-1 mutant. The recent discovery that the molybdenum cofactors of E. coli nitrate reductase and formate dehydrogenase contain molybdopterin guanine dinucleotide (MGD) rather than the simpler molybdopterin (MPT) raised the possibility that the chlB locus could be essential for the biosynthesis of MGD from MPT. To test this, conditions were devised for conversion of MGD to a fluorescent, stable derivative, Form A-GMP, and the absorption, fluorescence and chromatographic properties of Form A-GMP were established. Both Form A, arising from MPT, and Form A-GMP arising from MGD, were quantitated in extracts of wild type and chlB cells. Wild type cells were found to contain both Form A and Form A-GMP. In contrast, chlB cells contained elevated levels of Form A but no Form A-GMP. These results suggest that the chlB gene product is essential for the conversion of MPT to MGD.

• OSTI ID: 5373115
• Report Number(s): CONF-9104107--
• Conference Information: Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States) Journal Volume: 5:4
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL PATHWAYS
CHEMICAL COMPOSITION
CHROMATOGRAPHY
ELEMENTS
ENZYMES
ESCHERICHIA COLI
FLUORESCENCE
GENES
LUMINESCENCE
METABOLISM
METALLOPROTEINS
METALS
MICROORGANISMS
MOLYBDENUM
MUTANTS
NUCLEOTIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROTEINS
SEPARATION PROCESSES
TRANSITION ELEMENTS