D'Ippólito Sebastián, Arias Leonardo Agustín, Casalongué Claudia Anahí, Pagnussat Gabriela Carolina, Fiol Diego Fernando
Instituto de Investigaciones Biológicas, IIB-CONICET-Universidad Nacional de Mar del Plata, Funes 3250 Cuarto Nivel, 7600, Mar del Plata, Argentina.
Plant J. 2017 Apr;90(2):261-275. doi: 10.1111/tpj.13486. Epub 2017 Mar 14.
In this work we identified VACUOLELESS GAMETOPHYTES (VLG) as a DC1 domain-containing protein present in the endomembrane system and essential for development of both female and male gametophytes. VLG was originally annotated as a gene coding for a protein of unknown function containing DC1 domains. DC1 domains are cysteine- and histidine-rich zinc finger domains found exclusively in the plant kingdom that have been named on the basis of similarity with the C1 domain present in protein kinase C (PKC). In Arabidopsis, both male and female gametophytes are characterized by the formation of a large vacuole early in development; this is absent in vlg mutant plants. As a consequence, development is arrested in embryo sacs and pollen grains at the first mitotic division. VLG is specifically located in multivesicular bodies or pre-vacuolar compartments, and our results suggest that vesicular fusion is affected in the mutants, disrupting vacuole formation. Supporting this idea, AtPVA12 - a member of the SNARE vesicle-associated protein family and previously related to a sterol-binding protein, was identified as a VLG interactor. A role for VLG is proposed mediating vesicular fusion in plants as part of the sterol trafficking machinery required for vacuole biogenesis in plants.
在本研究中，我们鉴定出无液泡配子体（VLG）是一种存在于内膜系统中的含DC1结构域的蛋白质，对雌、雄配子体的发育至关重要。VLG最初被注释为一个编码含有DC1结构域但功能未知的蛋白质的基因。DC1结构域是富含半胱氨酸和组氨酸的锌指结构域，仅在植物界中发现，其命名基于与蛋白激酶C（PKC）中存在的C1结构域的相似性。在拟南芥中，雌、雄配子体在发育早期均以形成一个大液泡为特征；而在vlg突变体植物中则不存在这种情况。因此，胚囊和花粉粒的发育在第一次有丝分裂时就会停止。VLG特异性定位于多囊泡体或前液泡区室，我们的结果表明突变体中的囊泡融合受到影响，从而破坏了液泡形成。支持这一观点的是，AtPVA12（一种SNARE囊泡相关蛋白家族成员，之前与一种固醇结合蛋白有关）被鉴定为VLG相互作用蛋白。有人提出VLG在植物中作为植物液泡生物发生所需的固醇运输机制的一部分介导囊泡融合。
