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  • 1
    Electronic Resource
    Electronic Resource
    Isolation and characterization of peroxisomal protein import (Pim-) mutants of Hansenula polymorpha (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 8 (1992), S. 961-972 
    Details
    ISSN: 0749-503X
    Keywords: Yeast ; Hansenula polymorpha ; microbodies ; biogenesis ; PER genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the course of our studies on the molecular mechanisms involved in peroxisome biogenesis, we have isolated several mutants of the methylotrophic yeast Hansenula polymorpha impaired in the import of peroximal matrix proteins. These mutants are characterized by the presence of small intact peroxisomes, while the bulk of the peroxisomal matrix protein is not imported and resides in the cytosol (Pim- phenotype). Genetic analysis of back-crossed mutants revealed five different complementation groups, which were designated PERI-PER5. Mapping studies to determine the linkage relationships indicated that the observed Pim- phenotypes were determined by single recessive nuclear mutations.The different mutants had comparable phenotypes: (i) they were impaired to utilize methanol as the sole source of carbon and energy but grew well on various other compounds, including nitrogen sources, the metabolism of which is known to be mediated by peroxisome-borne enzymes in wild-type cells; (ii) all peroxisomal enzymes tested were induced, assembled and activated as in wild-type cells although their activities varied between the different representative mutants; (iii) all peroxisomal proteins, whether constitutive or inducible, were found both in the cytosol and in the small peroxisomes. These results suggest that a general, major import mechanism is affected in all mutants.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320081106
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  • 2
    Electronic Resource
    Electronic Resource
    Restoration of peroxisome formation in two conditional peroxisome-deficient mutants of Hansenula polymorpha during growth of cells on specific organic nitrogen sources (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 11 (1995), S. 1139-1145 
    Details
    ISSN: 0749-503X
    Keywords: yeast ; peroxisome biogenesis ; peroxisome-deficient mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Expression of the peroxisome-deficient (Per-) phenotype by per mutants of Hansenula polymorpha is shown to be dependent on specific environmental conditions. Analysis of our collection of constitutive and conditional per mutants showed that, irrespective of the carbon source used, the mutants invariably lacked functional peroxisomes when ammonium sulphate was used as a nitrogen source. However, in two temperature-sensitive (ts) mutants, per13-6ts and per14-11ts, peroxisomes were present at the restrictive temperature when cells were grown on organic nitrogen sources which are known to induce peroxisomes in wild-type cells, namely D-alanine (for both mutants) or methylamine (for per14-11ts). These organelles displayed normal wild-type properties with respect to morphology, mode of development and protein composition.However, under these conditions not all the peroxisomal matrix proteins synthesized were correctly located inside peroxisomes. Detailed biochemical and (immuno) cytochemical analyses indicated that during growth of cells on methanol in the presence of either D-alanine or methylamine, a minor portion of these proteins (predominantly alcohol oxidase, dihydroxyacetone synthase and catalase) still resided in the cytosol. This residual cytosolic activity may explain the observation that the functional restoration of the two ts mutants is not complete under these conditions, as is reflected by the retarded growth of the cells in batch cultures on methanol.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320111204
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  • 3
    Electronic Resource
    Electronic Resource
    Identification and characterization of cytosolic Hansenula polymorpha proteins belonging to the Hsp70 protein family (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 12 (1996), S. 849-857 
    Details
    ISSN: 0749-503X
    Keywords: heat shock proteins ; molecular chaperones ; stress tolerance ; peroxisome biogenesis ; Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated two members of the Hsp70 protein family from the yeast Hansenula polymorpha using affinity chromatography. Both proteins were located in the cytoplasm. One of these, designated Hsp72, was inducible in nature (e.g. by heat shock). The second protein (designated Hsc74) was constitutively present. Peptides derived from both Hsp72 and Hsc74 showed sequence homology to the cytosolic Saccharomyces cerevisiae Hsp70s, Ssa1p and Ssa2p. The gene encoding Hsp72 (designated HSA1) was cloned, sequenced and used to construct HSA1 disruption and HSA1 overexpression strains. Comparison of the stress tolerances of these strains with those of wild-type H. polymorpha revealed that HSA1 overexpression negatively affected the tolerance of the cells to killing effects of temperature or ethanol, but enhanced the tolerance to copper and cadmium. The tolerance for other chemicals (arsenite, arsenate, H2O2) or to high osmolarity was unaffected by either deletion or overexpression of HSA1. The nucleotide sequence of HSA1 was submitted to the EMBL data library and given the Accession Number Z29379.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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