Internucleosomal DNA fragmentation in wild emmer wheat is catalyzed by S1-type endonucleases translocated to the nucleus upon induction of cell death

S1-Type Endonuclease 2 in Dedifferentiating Arabidopsis Protoplasts: Translocation to the Nucleus in Senescing Protoplasts Is Associated with De-Glycosylation

“…Interestingly, ENDO2 displayed a peculiar localization in protoplasts, that is, cytoplasmic in healthy cells, often showed distinct localization within nucleoli; in senescing protoplast cells ENDO2-GFP showed association with fragmented nuclei. This mode of localization is similar to that reported for wheat endonuclease TaS1L in Arabidopsis protoplasts [13]. Also, transient expression of BFN1/ENDO1 in tobacco protoplast cells showed cytoplasmic, ER-associated localization in normal tobacco protoplasts but localization around nuclei in senescing protoplasts [19].…”

“…Endonucleases are known to be modified by N-glycosylation, which is often required for their activity. ENDO2 contains two N-glycosylation sites required for activity [30], which appear to be conserved among plant endonucleases [13]. We used Concanavalin A (ConA)-agarose to pull down glycoproteins from protein extracts derived from protoplasts 24 h after isolation, which were eluted with mannose followed by in-gel nuclease assay.…”

“…Results showed (Fig 4B) that in healthy protoplasts ENDO2-GFP is essentially localized in the cytoplasm surrounding chloroplasts in a speckle-like or thread-like distribution, co-localized with the ER marker CNX-RFP. This localization pattern reminiscent that of wheat S1-type endonuclease TaS1L-GFP in Arabidopsis protoplasts [13] as well as of BFN1/ENDO1 in tobacco protoplasts [19]. To investigate localization of ENDO2-GFP in the nucleus, we co-transformed protoplasts with ENDO2-GFP and AtMBD5-RFP, a nuclear-localized protein [31].…”

“…Plant endonucleases are divided into two classes based on their requirement for divalent cations for activity, namely, Zn 2+ -dependent endonucleases and Ca 2+ -dependent endonucleases [10] (Sugiyama et al, 2000). They are commonly bifunctional enzymes that can efficiently degrade single stranded DNAs (ssDNAs) and RNAs but they are almost not active toward double stranded DNA (dsDNA, [11–13]. S1/P1-type endonucleases were isolated from a variety of plant species [10] and based on their amino acid sequence they were classified as orthologs of the well known fungal S1 and P1 nucleases from Aspergillus oryzae and Penicillium citrinum , respectively [14].…”

The Dead Can Nurture: Novel Insights into the Function of Dead Organs Enclosing Embryos

“…The proteome data also revealed S1 type endonucleases, which are released from DOEEs upon hydration [16,20,21]. Endonucleases, in general, are involved in multiple cellular processes including DNA synthesis and DNA repair [31] and in PCD [32,33,34]. The capacity of endonucleases to target unpaired regions within superhelical DNA to introduce nicks and double strand DNA breaks may implicate them as defense factors against plasmid-containing soil pathogens such as the Clavibacter michiganensis subsp.…”