The cytoplasmic portion of the T3SS inner membrane ring components sort into distinct families based on biophysical properties

Publication date: Available online 10 June 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Meenakumari Muthuramalingam, C. Russell Middaugh, William D. PickingAbstractType III secretion systems are used by many Gram-negative bacteria to inject effector proteins into eukaryotic cells to subvert their normal activities. Structurally conserved portions of the type III secretion apparatus include a: basal body located within the bacterial envelope; an exposed needle with tip complex that delivers effectors across the target cell membrane; and cytoplasmic sorting platform that selects cargo and powers secretion. While structurally conserved, the individual proteins that make up this nanomachine are typically not interchangeable though they do tend to fall into families. Here we selected a single domain from the inner membrane ring of the basal body from six different type III secretion systems (called SctD using a proposed unifying nomenclature). The selected domain creates an integral interface between the basal body and the sorting platform. Therefore, it represents a pivotal point between two distinct assemblies. All six protein domains possess a structural motif called a forkhead-associated-like (FHA-like) domain but differ greatly in their sequences and solution behaviors. These differences are used here to define family boundaries for these FHA-like domains. The data parallel, though not precisely, family boundaries defined by other protei...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research