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The Hansenula polymorpha PEX14 gene encodes a novel peroxisomal membrane protein essential for peroxisome biogenesis
Author(s) -
Komori Masayuki,
Rasmussen Søren W.,
Kiel Jan A.K.W.,
Baerends Richard J.S.,
Cregg James M.,
van der Klei Ida J.,
Veenhuis Marten
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.1.44
Subject(s) - peroxisome , biology , peroxisomal targeting signal , microbody , cytosol , biochemistry , mutant , complementation , protein targeting , biogenesis , membrane protein , gene , enzyme , membrane
We have cloned the Hansenula polymorpha PEX14 gene by functional complementation of the chemically induced pex14‐1 mutant, which lacked normal peroxisomes. The sequence of the PEX14 gene predicts a novel protein product (Pex14p) of 39 kDa which showed no similarity to any known protein and lacked either of the two known peroxisomal targeting signals. Biochemical and electron microscopical analysis indicated that Pex14p is a component of the peroxisomal membrane. The synthesis of Pex14p is induced by peroxisome‐inducing growth conditions. In cells of both pex14‐1 and a PEX14 disruption mutant, peroxisomal membrane remnants were evident; these contained the H.polymorpha peroxisomal membrane protein Pex3p together with a small amount of the major peroxisomal matrix proteins alcohol oxidase, catalase and dihydroxyacetone synthase, the bulk of which resided in the cytosol. Unexpectedly, overproduction of Pex14p in wild‐type H.polymorpha cells resulted in a peroxisome‐deficient phenotype typified by the presence of numerous small vesicles which lacked matrix proteins; these were localized in the cytosol. Apparently, the stoichiometry of Pex14p relative to one or more other components of the peroxisome biogenesis machinery appears to be critical for protein import.