Biology subjects

Abu-Abied, M.

Publications and source records attributed to Abu-Abied, M..

3 recordsLinked to original sources

bioRxiv2022

CWLP and PRP940 form plasma-membrane nanodomain complexes with aquaporins, interact with PP2A and contribute to dehydration tolerance

The C-type hybrid-proline-rich protein (HyPRP) AtCWLP and its homolog AtPRP940 are referred as cell wall (CW)-plasma-membrane (PM) linker proteins, but little is known about their functions. Here we show that N-terminal proline-rich domains of CWLP and PRP940, containing glycosylated hydroxyproline residues, contact the CW, while their C-terminal 8CM domains function as PM-scaffolds. Both proteins are detected in PM nanodomains (PM-ND) and show co-localization and co-immunoprecipitation with aquaporins PIP2;1 and PIP2;7. Inhibition of actin polymerization by latrunculin B promotes CWLP-endosome appearance, while blocking the actomyosin-based transport by a truncated form of myosin XI-K relaxes lateral boundaries of CWLP-PIP2;1 PD-NDs. Mass spectrometry data indicate that CWLP co-purifies with dynamins implicated in fission of endocytic PD-ND invaginations. Lack of co-localization and co-immunoprecipitation with aquaporin-binding flotillin (FLOT2) indicates that CWLP and PRP940 mark a new distinct type of PM-ND. Yeast two-hybrid and co-immunoprecipitation assays demonstrate that CWLP and PRP940 interact with multiple aquaporins and several protein phosphatase PP2A-B regulatory subunits. By preventing irreversible separation of CW and PM, and likely assisting PP2A-mediated dephosphorylation of aquaporins and closure of their water channels, overexpression of CWLP confers tolerance to plasmolysis, dehydration and freezing in Arabidopsis and to water shortage in potato plants. Summary StatementArabidopsis Hybrid-Proline-Rich Proteins CWLP and PRP940 occur in association with dynamins, recruit PP2A protein phosphatases to aquaporin water channels in plasma-membrane (PM) nanodomains and elevate tolerance to cellular dehydration.

plant biology↗

bioRxiv2022

Two independent loss-of-function mutations in anthocyanidin synthase homeologous genes make sweet basil all green

Sweet basil, Ocimum basilicum L., is an important culinary herb grown worldwide. Although basil is green, many landraces, breeding lines and exotic cultivars have purple stems and flowers. This anthocyanins pigmentation is unacceptable in the traditional Italian basil. We used the recently published sweet basil genome to map quantitative trait loci (QTL) for flower and stem color in a bi-parental F2 population. It was found that the pigmentation is governed by a single QTL, harboring an anthocyanidin synthase (ANS) gene. Further analysis revealed that the basil genome harbors two homeologous ANS genes, each carrying a loss-of-function mutation. ObANS1 carries a 1-bp insertion, and ObANS2 carries a missense mutation within the active site. In the purple-flower parent, ANS1 is functional and ANS2 carries a nonsense mutation. The functionality of the active allele was validated by complementation in an Arabidopsis ANS mutant. Moreover, we have restored the functionality of the missense-mutated ANS2 using site-directed activation. We found that the non-functional alleles were expressed to similar levels as the functional allele, suggesting polyploids invest futile effort in expressing non-functional genes, harming their superior redundancy. We show here we can harness basils genomics and genetics to understand the basic mechanism of metabolic traits.

plant biology↗

bioRxiv2019

Vacuolar processing enzyme translocates to the vacuole through the autophagy pathway to induce programmed cell death

The caspase-like vacuolar processing enzyme (VPE) is a key factor in programmed cell death (PCD) associated with plant stress responses. Growth medium lacking a carbon source and dark conditions caused punctate labeling of 35S::VPE1-GFP (StVPE1-GFP) in potato leaves. Carbon starvation of BY-2 cells induced higher VPE activity and PCD symptoms. Growing VPE-RNAi BY-2 cells without sucrose reduced VPE activity and prevented PCD symptoms. During extended exposure to carbon starvation, VPE expression and activity levels peaked, with a gradual increase in BY-2 cell death. Histological analysis of StVPE1-GFP in BY-2 cells showed that carbon starvation induces its translocation from the endoplasmic reticulum to the central vacuole, through tonoplast engulfment. Exposure of BY-2 culture to the autophagy inhibitor concanamycin A caused autophagic bodies accumulation in the cell vacuole. Such accumulation did not occur in the presence of 3-methyladenine, an inhibitor of early-stage autophagy. BY-2 cells constitutively expressing StATG8IL-RFP, an autophagosome marker, showed colocalization with the StVPE1-GFP protein in the cytoplasm and vacuole. RNAi silencing of the core autophagy component ATG4 in BY-2 cells reduced VPE activity and cell death. These results are the first to suggest that VPE translocates to the cell vacuole through the autophagy pathway, leading to PCD.\n\nOne sentence summaryCarbon starvation induced programmed cell death by trafficking vacuolar processing enzyme through the autophagy pathway to the vacuole.

plant biology↗