Isolation and characterization of a new gene, sre, which encodes a GATA-type regulatory protein that controls iron transport in Neurospora crassa

ABSTRACT In this work, the LysR-type protein XapR has been subjected to a mutational analysis. XapR regulates the expression of xanthosine phosphorylase (XapA), a purine nucleoside phosphorylase inEscherichia coli. In the wild type, full expression of XapA requires both a functional XapR protein and the inducer xanthosine. Here we show that deoxyinosine can also function as an inducer in the wild type, although not to the same extent as xanthosine. We have isolated and characterized in detail the mutants that can be induced by other nucleosides as well as xanthosine. Sequencing of the mutants has revealed that two regions in XapR are important for correct interactions between the inducer and XapR. One region is defined by amino acids 104 and 132, and the other region, containing most of the isolated mutations, is found between amino acids 203 and 210. These regions, when modelled into the three-dimensional structure of CysB from Klebsiella aerogenes, are placed close together and are most probably directly involved in binding the inducer xanthosine.

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Isolation and Characterization of a Mitochondrially Synthesized Polypeptide from Neurospora crassa cni-1 Mutant

Hoppe-Seyler´s Zeitschrift für physiologische Chemie ◽

10.1515/bchm2.1975.356.2.1595 ◽

1975 ◽

Vol 356 (2) ◽

pp. 1595-1604 ◽

Cited By ~ 7

Author(s):

Rainer Michel ◽

Anton Liebl ◽

Werner Machleidt ◽

Joachim Otto ◽

Walter Neupert

Keyword(s):

Neurospora Crassa ◽

Isolation And Characterization

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ISOLATION AND CHARACTERIZATION OF CHROMATIN FROM NEUROSPORA CRASSA

The Journal of Cell Biology ◽

10.1083/jcb.43.1.51 ◽

1969 ◽

Vol 43 (1) ◽

pp. 51-58 ◽

Cited By ~ 38

Author(s):

R. S. Dwivedi ◽

S. K. Dutta ◽

D. P. Bloch

Keyword(s):

Amino Acid ◽

Neurospora Crassa ◽

Polyacrylamide Gel Electrophoresis ◽

Average Diameter ◽

Uv Absorption ◽

Eosin Y ◽

Basic Proteins ◽

Isolation And Characterization ◽

Calf Thymus

Different preparations of chromatin isolated from mycelia of Neurospora crassa were analyzed for DNA-associated RNA and proteins. The UV absorption spectra, the ultrastructure of chromatin, and the amino acid composition of the acid-extractable proteins were studied. The protein:DNA ratios range from 1.5 to 2.8; the RNA:DNA ratios range from 0.5 to 1.24. UV absorption shows a macimum at 259 mµ and a minimum at 238–239 mµ. The E280/E260 ranges from 0.59 to 0.70. Electron microscopy reveals a fibrous structure with individual fibers of 120–150 A average diameter. Attempts were made to study the protein by polyacrylamide gel electrophoresis and amino acid analysis. The results indicate that Neurospora chromatin does not contain basic proteins comparable to calf thymus histone. The ratios of basic to acidic amino acids range from 0.93 to 1.19. On electrophoresis, no bands are seen whose positions correspond to those of histones. Staining for basic proteins with fast green or eosin Y at pH 8.2 also shows a negative reaction, suggesting the absence of histones.

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