高等植物EIN3/EILs转录因子研究进展

Ethylene-insensitive3(EIN3)和EIN3-like(EIL)蛋白是乙烯信号转导途径中重要的核转录因子。目前已经从多种高等植物中分离得到EIN3/EILs,其属于一个小的转录因子家族。这类转录因子在氨基酸序列N端高度保守,包括酸性氨基酸区、脯氨酸富集区、碱性氨基酸簇等涉及DNA结合的重要结构域,它们通过直接结合到初级乙烯反应元件(PERE)上来调节相关基因的表达。EIN3/EILs转录因子家族不同成员在不同物种间时空表达特性、表达调控模式等均有所差异,各成员主要参与调节植物对乙烯的反应,包括影响幼苗的"三重反应"、植株的生长发育等,并作为乙烯与其他信号间交叉点发挥重要作用。就近几年关于高等植物EIN3/EILs转录因子的研究进展进行综述,以期为后续研究提供理论依据。     

Replication Protein A (RPA): The Eukaryotic SSB

Replication protein A (RPA) is a heterotrimeric single-stranded DNA-binding protein that is highly conserved in eukaryotes. RPA plays essential roles in many aspects of nucleic acid metabolism, including DNA replication, nucleotide excision repair, and homologous recombination. In this review, we provide a comprehensive overview of RPA structure and function and highlight the more recent developments in these areas. The last few years have seen major advances in our understanding of the mechanism of RPA binding to DNA, including the structural characterization of the primary DNA-binding domains (DBD) and the identification of two secondary DBDs. Moreover, evidence indicates that RPA utilizes a multistep pathway to bind single-stranded DNA involving a particular molecular polarity of RPA, a mechanism that is apparently used to facilitate origin denaturation. In addition to its mechanistic roles, RPA interacts with many key factors in nucleic acid metabolism, and we discuss the critical nature of many of these interactions to DNA metabolism. RPA is a phosphorylation target for DNA-dependent protein kinase (DNA-PK) and likely the ataxia telangiectasia-mutated gene (ATM) protein kinase, and recent observations are described that suggest that RPA phosphorylation plays a significant modulatory role in the cellular response to DNA damage.