Hansenula polymorpha Pex37 is a peroxisomal membrane protein required for organelle fission and segregation

Abstract

Here, we describe a novel peroxin, Pex37, in the yeast Hansenula polymorpha. H. polymorpha Pex37 is a peroxisomal membrane protein, which belongs to a protein family that includes, among others, the Neurospora crassa Woronin body protein Wsc, the human peroxisomal membrane protein PXMP2, the Saccharomyces cerevisiae mitochondrial inner membrane protein Sym1, and its mammalian homologue MPV17. We show that deletion of H. polymorpha PEX37 does not appear to have a significant effect on peroxisome biogenesis or proliferation in cells grown at peroxisome‐inducing growth conditions (methanol). However, the absence of Pex37 results in a reduction in peroxisome numbers and a defect in peroxisome segregation in cells grown at peroxisome‐repressing conditions (glucose). Conversely, overproduction of Pex37 in glucose‐grown cells results in an increase in peroxisome numbers in conjunction with a decrease in their size. The increase in numbers in PEX37‐overexpressing cells depends on the dynamin‐related protein Dnm1. Together our data suggest that Pex37 is involved in peroxisome fission in glucose‐grown cells. Introduction of human PXMP2 in H. polymorpha pex37 cells partially restored the peroxisomal phenotype, indicating that PXMP2 represents a functional homologue of Pex37. H.polymorpha pex37 cells did not show aberrant growth on any of the tested carbon and nitrogen sources that are metabolized by peroxisomal enzymes, suggesting that Pex37 may not fulfill an essential function in transport of these substrates or compounds required for their metabolism across the peroxisomal membrane.

CRISPR-Based Transcriptional Activation Tool for Silent Genes in Filamentous Fungi

“…Confocal imaging was performed on a Carl Zeiss LSM800 confocal microscope using 20x objective and ZEN 2009 software (Carl Zeiss, Oberkochen, Germany). The DsRed signal was visualized by excitation with a 543 nm helium neon laser (Lasos Lasertechnik, Jena, Germany), and emission was detected using a 565 to 615 nm band-pass emission filter 61 .…”

The novel peroxin Pex37: the Pxmp2 family joins the peroxisomal fission machinery

“…Despite species‐specific variations in the molecular composition of the fission machinery, the central mechanistic factors can be assigned to two groups: the Pex11 family and the dynamin‐related protein (DRP) family. In a recent study, Singh et al describe the involvement of a member of the Pxmp2‐related protein family in peroxisome fission: the novel peroxin Pex37.…”

“…Direct evidence for the existence of a clearly condition‐selective fission machinery component in addition to the Pex11 family and DRP family was presented in a recent study by Singh et al . in the methylotrophic yeast Hansenula polymorpha . In this organism, Dnm1 is the only DLP required for the scission step both under peroxisome‐inducing conditions (methanol medium) and under peroxisome‐repressing conditions (glucose medium) .…”

“…The novel peroxin Pex37 (Hp32g403) affects peroxisome abundance only in glucose‐grown but not in methanol‐grown cells . The fission and segregation phenotype of pex37 Δ cells differs from the other mutant strains in that the single peroxisome is either present in the mother cell or in the daughter cell.…”

“…Another interesting aspect of Pex37 is that it has been identified as a H. polymorpha homolog of the human Pxmp2, which is one of the founding members of the Pxmp2‐related protein family . These proteins share a common consensus sequence and four hydrophobic motifs that might represent transmembrane domains.…”