Effect of cysteine on methionine production by a regulatory mutant of Corynebacterium lilium

The ars-1+ gene of Neurospora crassa encodes the enzyme arylsulfatase. ars-1+ is in a group of highly regulated sulfur-related structural genes that are expressed under conditions of sulfur limitation and are under coordinate control of the cys-3+ and scon+ regulatory genes. The ars-1+ gene was cloned by chromosome walking from the qa gene cluster, using a lambda library. Cotransformation of an N. crassa ars-1 mutant with the isolated lambda clones and the benomyl resistance gene, followed by assay for arylsulfatase activity, was used to screen for the ars-1+ gene. Further confirmation that the cloned segment mapped to the ars-1+ locus was obtained by restriction-fragment-length polymorphism analysis. Northern (RNA) blot analysis showed that the ars-1+ gene was transcribed to give an mRNA of 2.3 kilobases. In wild-type cells, the ars-1+ transcript was abundant under sulfur-derepressing conditions but absent under repressing conditions. Time course analysis showed that the appearance of ars-1+ message in sulfur-derepressed cultures paralleled the appearance of arylsulfatase enzyme activity. In addition, transcription of ars-1+ was detected only under derepressing conditions in a nuclear transcription assay. In a cys-3 regulatory mutant that was unable to synthesize arylsulfatase (or other sulfur-controlled enzymes), there was no ars-1+ transcript under repressing or derepressing conditions. In a temperature-sensitive cys-3 mutant, the ars-1+ transcript was present only at the permissive growth temperature and under sulfur derepression. A negative regulatory mutant, sconc, displayed both constitutive expression of arylsulfatase enzyme activity and content of ars-1+ message.

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Expression of Invasin and Motility Are Coordinately Regulated in Yersinia enterocolitica

Journal of Bacteriology ◽

10.1128/jb.180.4.793-800.1998 ◽

1998 ◽

Vol 180 (4) ◽

pp. 793-800 ◽

Cited By ~ 45

Author(s):

Julie L. Badger ◽

Virginia L. Miller

Keyword(s):

Stationary Phase ◽

Yersinia Enterocolitica ◽

Growth Phase ◽

Temperature Regulation ◽

Molecular Basis ◽

Early Stationary Phase ◽

Regulatory Mutants ◽

E Coli ◽

Regulatory Mutant

ABSTRACT The Yersinia enterocolitica inv gene encodes the primary invasion factor invasin, which has been previously shown to be critical in the initial stages of infection. The expression ofinv is influenced by growth phase and temperature and is maximal during late exponential-early stationary phase at 23°C. In addition, motility of Y. enterocolitica is regulated by temperature. Y. enterocolitica cells are motile when grown at lower temperatures (30°C or below), while bacteria grown at 37°C are nonmotile. This study was initiated to determine the molecular basis for the temperature regulation of inv expression. Two mutants were isolated that both showed a significant decrease in invasin expression but are hypermotile when grown at 23°C. The first mutant (JB1A8v) was a result of a random mTn5Km insertion into the uvrC gene. The uvrC mutant JB1A8v demonstrated a significant decrease in inv and an increase in fleB (encodes flagellin) expression. These results suggest that expression of inv and flagellin genes is coordinated at the level of transcription. The second regulatory mutant, JB16v, was a result of a targeted insertion into a locus similar to sspA which in E. coli encodes a stationary-phase regulator. The E. coli sspA gene was cloned and assayed for complementation in both of the regulatory mutants. It was determined that E. coli sspA restored invasin expression in both the uvrC mutant and thesspA mutant. In addition, the complementing clone decreased flagellin levels in these mutants.

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A Regulatory Mutant of Hansenula polymorpha Exhibiting Methanol Utilization Metabolism and Peroxisome Proliferation in Glucose

Journal of Bacteriology ◽

10.1128/jb.180.11.2958-2967.1998 ◽

1998 ◽

Vol 180 (11) ◽

pp. 2958-2967 ◽

Cited By ~ 15

Author(s):

Giuseppinia Parpinello ◽

Enrico Berardi ◽

Rosanna Strabbioli

Keyword(s):

Hansenula Polymorpha ◽

Recessive Mutation ◽

Minor Role ◽

Peroxisome Proliferation ◽

Regulatory Mutant ◽

Pleiotropic Phenotype ◽

Methanol Utilization ◽

Induction Process ◽

A Minor

ABSTRACT Mutant LGM-128 of Hansenula polymorpha harbors the recessive mutation glr2-1 which confers a complex pleiotropic phenotype, the major feature of which is the metabolically unnecessary induction of methanol utilization metabolism (C1 metabolism) during growth on glucose, whether or not methanol is in the medium. Therefore, in this mutant, peroxisomes are formed and proliferate upon cultivation in glucose-containing media. In these media, LGM-128 shows induction levels of C1metabolism that are similar to those observed in methanol-containing media. This indicates that GLR2 controls the repression-derepression process stimulated by glucose and that the induction process triggered by methanol plays only a minor role in activating C1 metabolism. Cultivating LGM-128 in methanol and then transferring it to glucose media revealed that active degradative processes occur, leading to the disappearance of C1 metabolism. This observation suggests that, although stimulated by glucose, the two processes are controlled by elements which are, at least in part, distinct. Finally, glr2-1 does not affect ethanol repression, suggesting that in H. polymorpha the two repressing circuits are separated.

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