Dysferlin Domain-containing Proteins, Pex30p and Pex31p, Localized to Two Compartments, Control the Number and Size of Oleate-induced Peroxisomes in Pichia pastoris

Mingda Yan,* Dorian A. Rachubinski, ${dagger}$ Saurabh Joshi,* Richard A. Rachubinski, ${dagger}$ and Suresh Subramani*

^*Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322; Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada

Monitoring Editor: Janet Shaw

Yarrowia lipolytica Pex23p andS. cerevisiae Pex30p, Pex31p and Pex32p comprise a family ofdysferlin domain-containing peroxins. We show that the deletionof their Pichia pastoris homologues, PEX30 and PEX31, does notaffect the function or division of methanol-induced peroxisomesbut results in fewer and enlarged, functional, oleate-inducedperoxisomes. Synthesis of Pex30p is constitutive, while thatof Pex31p is oleate-induced but at a much lower level relativeto Pex30p. Pex30p interacts with Pex31p and is required forits stability. At steady-state, both Pex30p and Pex31p exhibita dual localization to the endoplasmic reticulum (ER) and peroxisomes.However, Pex30p is localized mostly to the ER, while Pex31pis predominantly on peroxisomes. Consistent with ER-to-peroxisometrafficking of these proteins, Pex30p accumulates on peroxisomesupon overexpression of Pex31p. Additionally, Pex31p colocalizeswith Pex30p at the ER in pex19 ${Delta}$ cells and can be chased fromthe ER to peroxisomes in a Pex19p-dependent manner. The dysferlindomains of Pex30p and Pex31p, which are dispensable for theirinteraction, stability and subcellular localization, are essentialfor normal peroxisome number and size. The growth environment-specificrole of these peroxins, their dual localization and the functionof their dysferlin domains provide novel insights into peroxisomemorphogenesis.

Address correspondence to: Suresh Subramani (ssubramani{at}ucsd.edu)