RESUMEN
Despite the central role of division in bacterial physiology, how division proteins work together as a nanoscale machine to divide the cell remains poorly understood. Cell division by cell wall synthesis proteins is guided by the cytoskeleton protein FtsZ, which assembles at mid-cell as a dense Z-ring formed of treadmilling filaments. However, although FtsZ treadmilling is essential for cell division, the function of FtsZ treadmilling remains unclear. Here, we systematically resolve the function of FtsZ treadmilling across each stage of division in the Gram-positive model organism Bacillus subtilis using a combination of nanofabrication, advanced microscopy, and microfluidics to measure the division-protein dynamics in live cells with ultrahigh sensitivity. We find that FtsZ treadmilling has two essential functions: mediating condensation of diffuse FtsZ filaments into a dense Z-ring, and initiating constriction by guiding septal cell wall synthesis. After constriction initiation, FtsZ treadmilling has a dispensable function in accelerating septal constriction rate. Our results show that FtsZ treadmilling is critical for assembling and initiating the bacterial cell division machine.
Asunto(s)
Bacillus subtilis/metabolismo , Proteínas Bacterianas/metabolismo , Pared Celular/metabolismo , Proteínas del Citoesqueleto/metabolismo , Guanosina Trifosfato/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/crecimiento & desarrollo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , División Celular , Pared Celular/ultraestructura , Proteínas del Citoesqueleto/química , Proteínas del Citoesqueleto/genética , Expresión Génica , Hidrólisis , Técnicas Analíticas Microfluídicas , Modelos Biológicos , Transporte de ProteínasRESUMEN
Filamentous plant pathogens deliver effector proteins to host cells to promote infection. The Phytophthora infestans RXLR-type effector PexRD54 binds potato ATG8 via its ATG8 family-interacting motif (AIM) and perturbs host-selective autophagy. However, the structural basis of this interaction remains unknown. Here, we define the crystal structure of PexRD54, which includes a modular architecture, including five tandem repeat domains, with the AIM sequence presented at the disordered C terminus. To determine the interface between PexRD54 and ATG8, we solved the crystal structure of potato ATG8CL in complex with a peptide comprising the effector's AIM sequence, and we established a model of the full-length PexRD54-ATG8CL complex using small angle x-ray scattering. Structure-informed deletion of the PexRD54 tandem domains reveals retention of ATG8CL binding in vitro and in planta This study offers new insights into structure/function relationships of oomycete RXLR effectors and how these proteins engage with host cell targets to promote disease.
Asunto(s)
Familia de las Proteínas 8 Relacionadas con la Autofagia , Phytophthora infestans , Enfermedades de las Plantas , Proteínas de Plantas , Solanum tuberosum , Familia de las Proteínas 8 Relacionadas con la Autofagia/química , Familia de las Proteínas 8 Relacionadas con la Autofagia/genética , Familia de las Proteínas 8 Relacionadas con la Autofagia/metabolismo , Cristalografía por Rayos X , Phytophthora infestans/química , Phytophthora infestans/genética , Phytophthora infestans/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Dominios Proteicos , Estructura Cuaternaria de Proteína , Solanum tuberosum/química , Solanum tuberosum/genética , Solanum tuberosum/metabolismoRESUMEN
Acute kidney injury (AKI) is an abrupt reduction in kidney function caused by different pathological processes. It is associated with a significant morbidity and mortality in the acute phase and an increased risk of developing End Stage Renal Disease. Despite the progress in the management of the disease, mortality rates in the last five decades remain unchanged at around 50%. Therefore there is an urgent need to find new therapeutic strategies to treat AKI. Lysosomal proteases, particularly Cathepsin D (CtsD), play multiple roles in apoptosis however, their role in AKI is still unknown. Here we describe a novel role for CtsD in AKI. CtsD expression was upregulated in damaged tubular cells in nephrotoxic and ischemia reperfusion (IRI) induced AKI. CtsD inhibition using Pepstatin A led to an improvement in kidney function, a reduction in apoptosis and a decrease in tubular cell damage in kidneys with nephrotoxic or IRI induced AKI. Pepstatin A treatment slowed interstitial fibrosis progression following IRI induced AKI. Renal transplant biopsies with acute tubular necrosis demonstrated high levels of CtsD in damaged tubular cells. These results support a role for CtsD in apoptosis during AKI opening new avenues for the treatment of AKI by targeting lysosomal proteases.
