The bacterial pathogen Legionella pneumophila delivers more than 330 effector proteins into host cells through its Dot/Icm type IV secretion system(T4SS)to facilitate its intracellular replication.A number of these ef...The bacterial pathogen Legionella pneumophila delivers more than 330 effector proteins into host cells through its Dot/Icm type IV secretion system(T4SS)to facilitate its intracellular replication.A number of these effectors modulate organelle trafficking pathways to create a membrane‐bound niche called the Legionella‐containing vacuole(LCV).In this study,we found that L.pneumophila induces F‐actin accumulation in the host cell cortex by its Dot/Icm substrate RavJ(Lpg0944).RavJ harbors a C101H138D170 motif associated with human tissue transglutaminases(TGs).We show that RavJ catalyzes a covalent linkage between actin and members of the Motin family of proteins,including Angiomotin(AMOT)and Angiomotin‐like 1(AMOTL1),which are known to regulate cell migration and contribute to the formation of cellular structures such as endothelial cell junctions and tubes.Further study reveals that RavJ‐induced crosslink between actin and AMOT occurs on its Gln354 residue.Crosslink between actin and AMOT significantly reduces the binding between actin and its binding partner cofilin,suggesting that RavJ inhibits actin depolymerization.We also demonstrate that the metaeffector LegL1 directly interacts with RavJ to antagonize its TG activity,leading to reduced crosslinks between actin and Motin proteins.Our results reveal a novel mechanism of modulating the host actin cytoskeleton by L.pneumophila.展开更多
The mitochondrion is an important signaling hub that governs diverse cellular functions,including metabolism,energy production,and immunity.Among the hundreds of effectors translocated into host cells by the Dot/Icm s...The mitochondrion is an important signaling hub that governs diverse cellular functions,including metabolism,energy production,and immunity.Among the hundreds of effectors translocated into host cells by the Dot/Icm system of Legionella pneumophila,several are targeted to mitochondria but the function of most of them remains elusive.Our recent study found that the effector Ceg3 inhibits the activity of ADP/ATP translocases(ANTs)by ADP-ribosylation(ADPR).Here,we show that the effect of Ceg3 is antagonized by Larg1,an effector encoded by lpg0081,a gene that is situated next to ceg3.Larg1 functions to reverse Ceg3-mediated ADPR of ANTs by cleaving the N-glycosidic bond between the ADPR moiety and the modified arginine residues in ANTs,leading to restoration of their activity in ADP/ATP exchange.Structural analysis of Larg1 and its complex with ADPR reveals that this ADPR glycohydrolase harbors a unique macrodomain that catalyzes the removal of ADPR modification on ANTs.Our results also demonstrate that together with Ceg3,Larg1 imposes temporal regulation of the activity of ANTs by reversible ADPR during L.pneumophila infection.展开更多
基金supported by National Institutes of Health grant R01AI127465(Zhao‐Qing Luo).
文摘The bacterial pathogen Legionella pneumophila delivers more than 330 effector proteins into host cells through its Dot/Icm type IV secretion system(T4SS)to facilitate its intracellular replication.A number of these effectors modulate organelle trafficking pathways to create a membrane‐bound niche called the Legionella‐containing vacuole(LCV).In this study,we found that L.pneumophila induces F‐actin accumulation in the host cell cortex by its Dot/Icm substrate RavJ(Lpg0944).RavJ harbors a C101H138D170 motif associated with human tissue transglutaminases(TGs).We show that RavJ catalyzes a covalent linkage between actin and members of the Motin family of proteins,including Angiomotin(AMOT)and Angiomotin‐like 1(AMOTL1),which are known to regulate cell migration and contribute to the formation of cellular structures such as endothelial cell junctions and tubes.Further study reveals that RavJ‐induced crosslink between actin and AMOT occurs on its Gln354 residue.Crosslink between actin and AMOT significantly reduces the binding between actin and its binding partner cofilin,suggesting that RavJ inhibits actin depolymerization.We also demonstrate that the metaeffector LegL1 directly interacts with RavJ to antagonize its TG activity,leading to reduced crosslinks between actin and Motin proteins.Our results reveal a novel mechanism of modulating the host actin cytoskeleton by L.pneumophila.
基金supported by National Institutes of Health grant R01AI127465(Zhao-Qing Luo)the National Nature Science Foundation of China grants 82172287,31770948(Songying Ouyang)and 32171265(Hongxin Guan)+1 种基金the Fujian Provincial Department of Science and Technology(2020Y4007,2021H0004)(Songying Ouyang)the High-level personnel introduction grant of Fujian Normal University(Z0210509)(Songying Ouyang).
文摘The mitochondrion is an important signaling hub that governs diverse cellular functions,including metabolism,energy production,and immunity.Among the hundreds of effectors translocated into host cells by the Dot/Icm system of Legionella pneumophila,several are targeted to mitochondria but the function of most of them remains elusive.Our recent study found that the effector Ceg3 inhibits the activity of ADP/ATP translocases(ANTs)by ADP-ribosylation(ADPR).Here,we show that the effect of Ceg3 is antagonized by Larg1,an effector encoded by lpg0081,a gene that is situated next to ceg3.Larg1 functions to reverse Ceg3-mediated ADPR of ANTs by cleaving the N-glycosidic bond between the ADPR moiety and the modified arginine residues in ANTs,leading to restoration of their activity in ADP/ATP exchange.Structural analysis of Larg1 and its complex with ADPR reveals that this ADPR glycohydrolase harbors a unique macrodomain that catalyzes the removal of ADPR modification on ANTs.Our results also demonstrate that together with Ceg3,Larg1 imposes temporal regulation of the activity of ANTs by reversible ADPR during L.pneumophila infection.
