Molecular organisation of the quinic acid utilization (QUT) gene cluster in Aspergillus nidulans

Hawkins, Alastair R.; Lamb, Heather K.; Smith, Monica; Keyte, John W.; Roberts, C. F.

doi:10.1007/bf00337715

Cited by 81 publications

(50 citation statements)

References 33 publications

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“…1. The seven members that were used for calculation included SuhB, bovine inositol monophosphatase (4), CysQ (which is involved in sulfate assimilation in E. coli) (25), Qut-G and Qa-X (which are hypothetical gene products from open reading frames in Aspergillus nidulans and Neurospora crassa, respectively) (8,12), bovine inositol polyphosphate 1-phosphatase (which hydrolyzes the 1-position phosphate of inositol 1,3,4-triphosphate and inositol 1,4-bisphosphate) (41), and Met22 (which is involved in salt tolerance in Saccharomyces cerevisiae) (9). Not only do these proteins share two sequence motifs (26), but the similarity is found throughout the length of the SuhB sequence (except for long insertions in inositol polyphosphate 1-phosphatase, Met22, Qut-G, and Qa-X).…”

Section: Resultsmentioning

confidence: 99%

Inositol monophosphatase activity from the Escherichia coli suhB gene product

et al. 1995

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The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (K m ‫؍‬ 0.071 mM; V max ‫؍‬ 12.3 mol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5 proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.The suhB gene was first identified as the locus for the ssyA3(Cs) mutation that was isolated as an extragenic suppressor for the secY24(Ts) mutant (31). The ssyA3 mutation restored the defect in protein secretion caused by the secY24 mutation (33) and rescued the temperature-sensitive cell growth of secY24 mutant cells. The ssyA3 mutation caused cold-sensitive cell growth by itself and impaired protein synthesis was observed in the ssyA3 mutant at low temperatures (31). The cold-sensitive growth of the ssyA3 mutant was rescued by introduction of the wild-type copy of suhB, indicating that ssyA3 is a mutant allele of suhB (40). The suhB2(Cs) mutation is another allele of suhB and was isolated as an extragenic suppressor of the rpoH15(Ts) mutation. The rpoH15 mutant gene produces an altered 32 protein and causes a defect in the induction of heat shock proteins at higher temperatures (42). The suhB2(Cs) mutation rescued the temperature-sensitive cell growth of the rpoH15 mutant and partially restored heat shock induction in the mutant cell (40). A coldsensitive mutation was also mapped in the suhB locus as an extragenic suppressor for the dnaB121(Ts) mutation that inhibits replication of phage (2). Thus, mutant alleles of suhB have effects on diverse cell activities, including protein export, stress response, and DNA replication.The suhB gene encodes a protein of 268 amino acids (40), and the primary structure of its translated product shows a high level of similarity t...

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Section: Resultsmentioning

confidence: 99%

Inositol monophosphatase activity from the Escherichia coli suhB gene product

et al. 1995

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“…(1-31) [6], the Aspergillus nidulans qutG gene (QutG) [7] and the E.schrrichiu co/i suhB (SuhB) [4] and nmtA [S] genes (AmtA), and to the C-terminal peptide fragment inferred from the 3'end of an ORF upstream from the Rhizobium kguminowrutn pss gene [8] yielded homology scores of 27, 35, 43, 21 and IO s.d. units, respectively.…”

Section: Mai)p------woecmdyav1'lagqagevvrealk--------------nemmentioning

confidence: 99%

“…Homologies between IMP and the products of the Neurospora crassa qa-x [6] and Aspergillus nidulans qutG [7] genes, which are both part of a cluster of genes involved in quinic acid utilization, have been reported previously [l]. A search of the GenBank database (release 67) using the FASTA program [3] uncovered a fifth homology to an open reading frame (ORF) upstream from the pss gene of Rhizobium leguminosarum [8] which is required for exopolysaccharide (EPS) synthesis and nodulation of peas.…”

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confidence: 99%

Diverse proteins homologous to inositol monophosphatase

Neuwald¹,

York²,

Majerus³

1991

FEBS Letters

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Bovine inositol monophosphatase (IMP) and several homologous proteins were found to share two sequence motifs with bovine inositol polyphosphate I-phosphatase (IPP). These motifs may correspond to binding sites within IMP and IPP for inositol phosphates or for lithium, since both substances are bound by these proteins. This suggests that the proteins homologous to IMP, which have diverse biological roles but whose function is not clear, may act by enhancing the synthesis or degradation of phosphorylated compounds.Amino acid sequence; Inositol phosphate; Signaling pathwayWe have found several proteins homologous to the inferred amino acid sequence of bovine inositol monophosphatase (IMP) [l], an enzyme of the inositol phosphate second messenger signaling pathway 121.A search of the PIR protein database (release 28.0) using the FASTA program of Pearson and Lipman [3] yielded homologies between IMP and 2 inferred Escherichia coli proteins: the products of the suhB and amtA genes, mutations which result in enhanced synthesis of the heat shock transcription sigma factor [4], and deficiency in ammonium transport [S], respectively. Homologies between IMP and the products of the Neurospora crassa qa-x [6] and Aspergillus nidulans qutG [7] genes, which are both part of a cluster of genes involved in quinic acid utilization, have been reported previously [l]. A search of the GenBank database (release 67) using the FASTA program [3] uncovered a fifth homology to an open reading frame (ORF) upstream from the pss gene of Rhizobium leguminosarum [8] which is required for exopolysaccharide (EPS) synthesis and nodulation of peas. (Only the 3' end of the sequence is known since the 5' end of this ORF was deleted during cloning of the fragment.)

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“…Quinic acid is an abundant biomass in the natural environment of A. nidulans that can be used as a (noncatabolite repressing) carbon source. 22 When quinic acid was used as carbon source in conjunction with 10 mm ammonium or nitrate, proteases were only detected in mycelium transferred to nitrogen free medium for 4 h. The reason for the apparent difference in protease production between glucose and quinic acid grown mycelium is likely to be due to a slower growth rate with quinic acid leading to a slower depletion of the nitrogen source during the overnight growth phase. This observation implies that the 38% diminution in nuclear NmrA levels seen in nitrate versus ammonium grown mycelium in the confocal microscopy experiments is not due to proteolysis.…”

Section: Production Of the Pnma B And C Protease Activities Is Assocmentioning

confidence: 99%

The transcription repressor NmrA is subject to proteolysis by three Aspergillus nidulans proteases

et al. 2010

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The role of specific cleavage of transcription repressor proteins by proteases and how this may be related to the emerging theme of dinucleotides as cellular signaling molecules is poorly characterized. The transcription repressor NmrA of Aspergillus nidulans discriminates between oxidized and reduced dinucleotides, however, dinucleotide binding has no effect on its interaction with the zinc finger in the transcription activator AreA. Protease activity in A. nidulans was assayed using NmrA as the substrate, and was absent in mycelium grown under nitrogen sufficient conditions but abundant in mycelium starved of nitrogen. One of the proteases was purified and identified as the protein Q5BAR4 encoded by the gene AN2366.2. Fluorescence confocal microscopy showed that the nuclear levels of NmrA were reduced approximately 38% when mycelium was grown on nitrate compared to ammonium and absent when starved of nitrogen. Proteolysis of NmrA occurred in an ordered manner by preferential digestion within a C-terminal surface exposed loop and subsequent digestion at other sites. NmrA digested at the C-terminal site was unable to bind to the AreA zinc finger. These data reveal a potential new layer of control of nitrogen metabolite repression by the ordered proteolytic cleavage of NmrA. NmrA digested at the C-terminal site retained the ability to bind NAD 1 and showed a resistance to further digestion that was enhanced by the presence of NAD 1 . This is the first time that an effect of dinucleotide binding to NmrA has been demonstrated.

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Molecular organisation of the quinic acid utilization (QUT) gene cluster in Aspergillus nidulans

Cited by 81 publications

References 33 publications

Inositol monophosphatase activity from the Escherichia coli suhB gene product

Inositol monophosphatase activity from the Escherichia coli suhB gene product

Diverse proteins homologous to inositol monophosphatase

The transcription repressor NmrA is subject to proteolysis by three Aspergillus nidulans proteases

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