Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México 04510, Mexico.
Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México 04510, Mexico.
Biochim Biophys Acta Mol Cell Res. 2018 Apr;1865(4):572-586. doi: 10.1016/j.bbamcr.2018.01.003. Epub 2018 Jan 4.
Peroxisomes are versatile organelles essential for diverse developmental processes. One such process is the meiotic development of Podospora anserina. In this fungus, absence of the docking peroxin PEX13, the RING-finger complex peroxins, or the PTS2 co-receptor PEX20 blocks sexual development before meiocyte formation. However, this defect is not seen in the absence of the receptors PEX5 and PEX7, or of the docking peroxins PEX14 and PEX14/17. Here we describe the function of the remaining uncharacterized P. anserina peroxins predictably involved in peroxisome matrix protein import. We show that PEX8, as well as the peroxins potentially mediating receptor monoubiquitination (PEX4 and PEX22) and membrane dislocation (PEX1, PEX6 and PEX26) are indeed implicated in peroxisome matrix protein import in this fungus. However, we observed that elimination of PEX4 and PEX22 affects to different extent the import of distinct PEX5 cargoes, suggesting differential ubiquitination-complex requirements for the import of distinct proteins. In addition, we found that elimination of PEX1, PEX6 or PEX26 results in loss of peroxisomes, suggesting that these peroxins restrain peroxisome removal in specific physiological conditions. Finally, we demonstrate that all analyzed peroxins are required for meiocyte formation, and that PEX20 function in this process depends on its potential monoubiquitination target cysteine. Our results suggest that meiotic induction relies on a peroxisome import pathway, which is not dependent on PEX5 or PEX7 but that is driven by an additional cycling receptor. These findings uncover a collection of peroxins implicated in modulating peroxisome activity to facilitate a critical developmental cell fate decision.
过氧化物酶体是多功能细胞器，对多种发育过程至关重要。其中一个过程是 Podospora anserina 的减数分裂发育。在这种真菌中，缺失对接过氧化酶 PEX13、RING 指复合物过氧化物酶或 PTS2 共受体 PEX20 会在减数分裂前阻止性细胞形成。然而，在缺乏受体 PEX5 和 PEX7 或对接过氧化酶 PEX14 和 PEX14/17 的情况下，不会出现这种缺陷。在这里，我们描述了可预测地参与过氧化物酶体基质蛋白输入的剩余未表征的 P. anserina 过氧化物酶的功能。我们表明，PEX8 以及可能介导受体单泛素化的过氧化物酶（PEX4 和 PEX22）和膜易位（PEX1、PEX6 和 PEX26）确实参与了该真菌过氧化物酶体基质蛋白的输入。然而，我们观察到消除 PEX4 和 PEX22 会不同程度地影响不同 PEX5 货物的输入，表明不同蛋白质的输入需要不同的泛素化复合物。此外，我们发现消除 PEX1、PEX6 或 PEX26 会导致过氧化物体丢失，这表明这些过氧化物酶在特定生理条件下抑制过氧化物体的去除。最后，我们证明所有分析的过氧化物酶都需要减数分裂形成，并且 PEX20 在这个过程中的功能依赖于其潜在的单泛素化靶标半胱氨酸。我们的结果表明，减数分裂诱导依赖于一种过氧化物酶体输入途径，该途径不依赖于 PEX5 或 PEX7，但由额外的循环受体驱动。这些发现揭示了一组过氧化物酶，它们参与调节过氧化物体活性以促进关键的发育细胞命运决定。
