Temasek Life Sciences Laboratory, and Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
PLoS One. 2013 Nov 1;8(11):e79128. doi: 10.1371/journal.pone.0079128. eCollection 2013.
Pexophagy, the degradation of peroxisomes via selective autophagy, depends on Atg20/Snx42 function in Saccharomyces cerevisiae. Besides its role in selective autophagy, Atg20/Snx42 is also involved in an autophagy-independent endosomal retrieval trafficking, in cooperation with two other sorting nexins, Snx41 and Snx4. Recently, we reported that the sorting nexin MoSnx41, which showed high sequence similarity to yeast Snx41 and Snx42/Atg20 proteins, regulates the gamma-glutamyl cycle and GSH production and is essential for conidiation and pathogenicity in Magnaporthe oryzae. Pexophagy was also found to be defective in Mosnx41Δ mutant. These findings indicate that MoSnx41 likely serves combined functions of Snx42/Atg20 and Snx41 in M. oryzae.. In this study, we performed complementation analyses and demonstrate that MoSnx41 alone serves the dual function of protein sorting (ScSnx41) and pexophagy (ScSnx42/Atg20). To study the potential biological function of pexophagy in fungal pathogenic life cycle, we created deletion mutants of potential pexophagy-specific genes, and characterized them in terms of pexophagy, conidiation and pathogenesis. We identified Pex14 as an essential protein for pexophagy in M. oryzae. Overall, our results show that pexophagy per se is not essential for asexual development or virulence in M. oryzae.
过氧化物酶体的降解通过选择性自噬来完成,这依赖于酿酒酵母中的 Atg20/Snx42 功能。除了在选择性自噬中的作用外,Atg20/Snx42 还参与了一种非依赖于自噬的内体回收运输过程,与另外两种分选连接蛋白 Snx41 和 Snx4 合作。最近,我们报道了分选连接蛋白 MoSnx41,它与酵母 Snx41 和 Snx42/Atg20 蛋白具有高度的序列相似性,调节γ-谷氨酰循环和 GSH 的产生,并且对稻瘟病菌的分生孢子形成和致病性是必需的。在 Mosnx41Δ突变体中也发现了过氧化物酶体自噬缺陷。这些发现表明,MoSnx41 可能在稻瘟病菌中具有 Snx42/Atg20 和 Snx41 的组合功能。在这项研究中,我们进行了互补分析,并证明 MoSnx41 单独具有分选蛋白(ScSnx41)和过氧化物酶体自噬(ScSnx42/Atg20)的双重功能。为了研究过氧化物酶体自噬在真菌致病生命周期中的潜在生物学功能,我们创建了潜在过氧化物酶体自噬特异性基因的缺失突变体,并对其进行了过氧化物酶体自噬、分生孢子形成和致病性的特征分析。我们确定 Pex14 是稻瘟病菌过氧化物酶体自噬所必需的蛋白。总的来说,我们的结果表明,过氧化物酶体自噬本身对于稻瘟病菌的无性发育或毒力并非必需。