tauABC

tauABC is a bacterial ATP-binding cassette (ABC) transporter system that mediates the uptake of taurine (2-aminoethanesulfonate) from the extracellular environment. The system is typically encoded by three adjacent genes: tauA, encoding a periplasmic taurine-binding protein; tauB, encoding the ATPase that provides energy for transport; and tauC, encoding the integral membrane permease that forms the translocation channel.

Functionally, TauA binds taurine in the periplasm and delivers it to the TauBC membrane complex. The TauB ATPase hydrolyzes ATP to drive conformational changes in TauC, enabling translocation of taurine into the cytoplasm. This substrate-specific uptake allows taurine to serve as a sulfur source for bacteria, particularly under conditions where other sulfur compounds are limited.

Genetically, tauABC is commonly organized as an operon and is regulated in response to sulfur availability and other environmental cues. Expression may be induced under sulfate-limited conditions or in the presence of taurine, and regulatory networks can vary among species. In some bacteria, tauABC is situated near other genes involved in taurine metabolism, creating a coordinated system for taurine utilization.

Structure and evolution considerations describe a classic two-component architecture: a periplasmic binding protein (TauA), a transmembrane permease (TauC), and a cytosolic ATPase (TauB). The components show characteristic ABC transporter domains and are adapted to efficiently import taurine into the cell.

TauABC plays a role in nitrogen and sulfur metabolism in certain bacteria and contributes to ecological flexibility in nutrient-poor environments. Related topics include ABC transporters and taurine metabolism pathways.