ESCn

EscN is an ATPase component of the type III secretion system (T3SS) found in several Gram-negative bacteria. It is typically encoded within T3SS gene clusters and is homologous to other system ATPases such as YscN and InvC, indicating a conserved mechanism across diverse pathogens. EscN's primary role is to provide the energy needed for secretion by hydrolyzing ATP.

In the secretion process, EscN acts as the cytoplasmic motor that drives the unfolding and translocation of effector proteins through the injectisome’s secretion channel. By coupling ATP hydrolysis to conformational changes in the secretion apparatus, EscN helps coordinate the passage of substrates from the bacterial cytoplasm to the host cell surface. In many systems it is thought to form a hexameric ring that interfaces with other components of the basal body and cytoplasmic complex.

Genomic studies show EscN is part of the highly conserved T3SS core across various pathogens, with species-specific variations in sequence but a shared functional role. The activity and expression of EscN are tightly regulated by environmental cues and regulatory networks that respond to host contact, nutrient status, and stress conditions, ensuring secretion is deployed when advantageous for infection.

Clinical and research relevance is notable because T3SS function, including EscN activity, contributes to virulence in plant and animal pathogens. As a central driver of energy for effector secretion, EscN is a focal point for studies aiming to develop anti-virulence strategies that disarm pathogens without necessarily killing them.