Mutants impaired in derepressible alkaline phosphatase activity in Chlamydomonas reinhardtii

Bachir, Fatima; Baise, Etienne; Loppes, Roland

doi:10.1016/0168-9452(96)04447-0

Cited by 8 publications

(8 citation statements)

References 24 publications

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“…As a whole, these results are in agreement with the hypothesis that DM is a minor phosphatase also present in the wild‐type but detectable only when both major phosphatases (DN and DA) are missing. The recent finding that the 58 kDa polypeptide corresponds to a protein displaying phosphatase activity [10] still confirms this hypothesis. In a very recent paper devoted to a “biochemical characterization of the extracellular phosphatases produced by phosphorus‐deprived Chlamydomonas reinhardtii ”, Quisel et al [17] also provide evidence for the occurrence of a minor phosphatase.…”

Section: Resultsmentioning

confidence: 71%

“…It has been shown recently [10] that phoN6 and phoA4 mutations are unlinked. To test whether R18 is linked to one of the genes, the revertant was crossed to phoN6 and phoA4 and the resulting progeny were examined for the occurrence of phosphatase‐negative phoN6 phoA4 recombinants.…”

Section: Resultsmentioning

confidence: 99%

“…Staining of colonies for phosphatase activity was performed at pH 7.0 as previously described [6]. Under these conditions, both DN and DA phosphatases are active [10]. It should be stressed that the staining reaction cannot be carried out at pH higher than 7.0 due to the formation of a heavy precipitate.…”

Section: Methodsmentioning

confidence: 99%

“…Four allelic phoA mutants impaired in DA phosphatase activity have been recently isolated after treatment of a phoN6 (a phoN2 allele) strain with ultraviolet light [10]. All phoN6 phoA mutants displayed a low but measurable phosphatase activity over the whole pH range with maximum activity at pH 9.5 and lacked both the 73 kDa subunit of DN and a 200 kDa polypeptide, a presumed component of the DA phosphatase [10].…”

Section: Introductionmentioning

confidence: 99%

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Identification of a new derepressible phosphatase in Chlamydomonas reinhardtii

Bachir

Loppes

2006

FEMS Microbiology Letters

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In the unicellular green alga Chlamydomonas reinhardtii there are two highly expressed derepressible phosphatases (DN and DA). Mutants altered in DN phosphatase (phoN) or/and DA phosphatase (phoA) activities are available. From the double mutant phoN6 phoA4 showing only some residual phosphatase activity at alkaline pH, a mutant (phoN6 phoA4 R18) displaying higher phosphatase activity at pH 9.5 was isolated. Comparative study of the phosphatase produced by the two strains revealed the enzymes to have very similar properties (Km for α‐naphthylphosphate, thermosensitivity, pH dependence). In addition, a 58 kDa polypeptide present in the wild‐type strain and previously described as a component of a derepressible phosphatase, was shown to be more abundant in phoN6 phoA4 R18. These results provide strong evidence that the residual enzyme in phoN6 phoA4 corresponds to a minor hitherto unknown phosphatase (DM) which is present in minute amounts in all Pi‐starved cells (including wild‐type where it is masked by the other phosphatases) and overproduced in phoN6 phoA4 R18.

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Identification of a new derepressible phosphatase in Chlamydomonas reinhardtii

Bachir

Loppes

2006

FEMS Microbiology Letters

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“…The DN phosphatase structural gene is still unidenti®ed. PhoA mutants speci®cally impaired in DA phosphatase activity have also been isolated and investigated (Bachir et al 1996). The proteins involved in phosphatase metabolism being uncharacterized, molecular probes are not available for cloning the corresponding genes.…”

Section: Introductionmentioning

confidence: 99%

Use of the ARG7 gene as an insertional mutagen to clone PHON 24, a gene required for derepressible neutral phosphatase activity in Chlamydomonas reinhardtii

Adam

Loppes

1998

Mol Gen Genet

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In Chlamydomonas reinhardtii, transforming DNA apparently integrates at random locations in the nuclear genome and generates a high number of mutants by gene inactivation. Twenty-four phoN mutants lacking the derepressible neutral (DN) phosphatase activity were isolated following transformation of the cw15arg7 strain with plasmid pASL harbouring the ARG7 gene encoding argininosuccinate lyase. In all mutants resulting from the transformation with linearised pASL, a functional ARG7 copy was found to be closely linked to a phoN mutation but additional ARG7 copies were present elsewhere in the genome. Of the 13 mutants submitted to allelism analysis, four were allelic or tightly linked to the previously isolated MNNG-induced phoN mutants (phoN2, phoN3, phoN24), the remaining mutants were distributed among seven additional loci. To learn more about the function of the genes involved in DN phosphatase production, we cloned PHON24 by plasmid rescue and screening of a wild-type genomic library. One clone complemented the phoN24 mutation in cotransformation experiments, as did several subcloned fragments. In all phoN24+ transformants, the DN phosphatase activity was 2-3 times lower than in the wild-type strain but about 10 times higher than in the untransformed control. In wild-type, PHON24 transcript accumulation was independent of inorganic phosphate deficiency. The transcripts were present in the MNNG-induced phoN24 mutant but were lacking in the two insertional phoN24 mutants. Insertional mutagenesis has thus permitted the isolation of novel mutants which were missing after induction with a chemical mutagen and the cloning of a gene which is probably involved in the regulation of the DN phosphatase.

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Responses to Deficiencies in Macronutrients

Davies

Grossman

The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas

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Mutants impaired in derepressible alkaline phosphatase activity in Chlamydomonas reinhardtii

Cited by 8 publications

References 24 publications

Identification of a new derepressible phosphatase in Chlamydomonas reinhardtii

Identification of a new derepressible phosphatase in Chlamydomonas reinhardtii

Use of the ARG7 gene as an insertional mutagen to clone PHON 24, a gene required for derepressible neutral phosphatase activity in Chlamydomonas reinhardtii

Responses to Deficiencies in Macronutrients

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