SctT

SctT is a protein component that appears in the gene clusters encoding type III secretion systems (T3SS) of various Gram-negative bacteria. The protein is named according to the common Sct (secretion and contact-dependent translocation) nomenclature used for injectisome components. SctT homologs have been identified in multiple species and are often encoded within operons together with other sct components such as sctC, sctD, and sctJ.

Localization and structure: Inferred from bioinformatic analyses and some experimental data, SctT is thought to associate with the inner membrane or the cytoplasmic face of the T3SS, contributing to the assembly or stability of the secretion apparatus. The precise topology and architecture of SctT can differ among species.

Function and interactions: SctT is generally considered part of the export or basal body region of the injectisome. It may participate in assembling the secretion channel or in coordinating export with energy-providing components. In some organisms, genetic disruption of sctT reduces secretion or alters complex formation, indicating a role in system integrity. Interaction with neighboring components such as SctD, SctJ, or the ATPase-associated module has been reported in certain studies.

Evolution and significance: SctT is widely conserved among T3SS-bearing bacteria, reflecting the integration of SctT into the conserved architecture of the injectisome. Because T3SS is a virulence determinant in many pathogens, SctT is frequently discussed in studies of secretion system function and as a potential target for therapeutic intervention.