Multiple repeats of membrane occupation and recognition nexus (MORN) motifs were detected in plant phosphatidylinositl monophosphate kinase (PIPK), a key enzyme in PI-signaling pathway. Structural analysis indicates t...Multiple repeats of membrane occupation and recognition nexus (MORN) motifs were detected in plant phosphatidylinositl monophosphate kinase (PIPK), a key enzyme in PI-signaling pathway. Structural analysis indicates that all the MORN motifs (with varied numbers at ranges of 7-9), which shared high homologies to those of animal ones, were located at N-terminus and sequentially arranged, except those of OsPIPK1 and AtPIPK7, in which the last MORN motif was separated others by an -100 amino-acid "island" region, revealing the presence of two kinds of MORN arrangements in plant PIPKs. Through employing a yeast-based SMET (sequence of membrane-targeting) system, the MORN motifs were shown being able to target the fusion proteins to cell plasma membrane, which were further confirmed by expression of fused MORN-GFP proteins. Further detailed analysis via deletion studies indicated the MORN motifs in OsPIPK 1, together with the 104 amino-acid "island" region are involved in the regulation of differential subcellular localization, i.e. plasma membrane or nucleus, of the fused proteins. Fat Western blot analysis of the recombinant MORN polypeptide, expressed in Escherichia coli, showed that MORN motifs could strongly bind to PA and relatively slightly to PI4P and PI(4,5)P2. These results provide informative hints on mechanisms of subcellular localization, as well as regulation of substrate binding, of plant PIPKs.展开更多
Lipid droplet(LD)in vegetative tissues has recently been implicated in environmental responses in plants,but its regulation and its function in stress tolerance are not well understood.Here,we identified a Membrane Oc...Lipid droplet(LD)in vegetative tissues has recently been implicated in environmental responses in plants,but its regulation and its function in stress tolerance are not well understood.Here,we identified a Membrane Occupation and Recognition Nexus 1(MORN1)gene as a contributor to natural variations of stress tolerance through genome-wide association study in Arabidopsis thaliana.Characterization of its loss-of-function mutant and natural variants revealed that the MORN1 gene is a positive regulator of plant growth,disease resistance,cold tolerance,and heat tolerance.The MORN1 protein is associated with the Golgi and is also partly associated with LD.Protein truncations that disrupt these associations abolished the biological function of the MORN1 protein.Furthermore,the MORN1 gene is a positive regulator of LD abundance,and its role in LD number regulation and stress tolerance is highly linked.Therefore,this study identifies MORN1 as a positive regulator of LD abundance and a contributor to natural variations of stress tolerance.It implicates a potential involvement of Golgi in LD biogenesis and strongly suggests a contribution of LD to diverse processes of plant growth and stress responses.展开更多
文摘Multiple repeats of membrane occupation and recognition nexus (MORN) motifs were detected in plant phosphatidylinositl monophosphate kinase (PIPK), a key enzyme in PI-signaling pathway. Structural analysis indicates that all the MORN motifs (with varied numbers at ranges of 7-9), which shared high homologies to those of animal ones, were located at N-terminus and sequentially arranged, except those of OsPIPK1 and AtPIPK7, in which the last MORN motif was separated others by an -100 amino-acid "island" region, revealing the presence of two kinds of MORN arrangements in plant PIPKs. Through employing a yeast-based SMET (sequence of membrane-targeting) system, the MORN motifs were shown being able to target the fusion proteins to cell plasma membrane, which were further confirmed by expression of fused MORN-GFP proteins. Further detailed analysis via deletion studies indicated the MORN motifs in OsPIPK 1, together with the 104 amino-acid "island" region are involved in the regulation of differential subcellular localization, i.e. plasma membrane or nucleus, of the fused proteins. Fat Western blot analysis of the recombinant MORN polypeptide, expressed in Escherichia coli, showed that MORN motifs could strongly bind to PA and relatively slightly to PI4P and PI(4,5)P2. These results provide informative hints on mechanisms of subcellular localization, as well as regulation of substrate binding, of plant PIPKs.
基金supported by National Science Foundation USA(IOS-1946174)to J.H.Cornell-ZJU seed grant+1 种基金Seed Grant of Cornell Institute of Biotechnologythe Major Science and Technology Research Projects of Guangdong Laboratory for Lingnan Modern Agriculture(NT2021001)。
文摘Lipid droplet(LD)in vegetative tissues has recently been implicated in environmental responses in plants,but its regulation and its function in stress tolerance are not well understood.Here,we identified a Membrane Occupation and Recognition Nexus 1(MORN1)gene as a contributor to natural variations of stress tolerance through genome-wide association study in Arabidopsis thaliana.Characterization of its loss-of-function mutant and natural variants revealed that the MORN1 gene is a positive regulator of plant growth,disease resistance,cold tolerance,and heat tolerance.The MORN1 protein is associated with the Golgi and is also partly associated with LD.Protein truncations that disrupt these associations abolished the biological function of the MORN1 protein.Furthermore,the MORN1 gene is a positive regulator of LD abundance,and its role in LD number regulation and stress tolerance is highly linked.Therefore,this study identifies MORN1 as a positive regulator of LD abundance and a contributor to natural variations of stress tolerance.It implicates a potential involvement of Golgi in LD biogenesis and strongly suggests a contribution of LD to diverse processes of plant growth and stress responses.
