TatC2 is Important for Growth of Acinetobacter baylyi Under Stress Conditions

Abstract

Protein export pathways are important for bacterial physiology among pathogens and non-pathogens alike. This includes the Twin-Arginine Translocation (Tat) pathway, which transports fully folded proteins across the bacterial cytoplasmic membrane. Some Tat substrates are virulence factors, while others are important for cellular processes like peptidoglycan remodeling. Some bacteria encode more than one copy of each Tat component, including the Gram-negative soil isolate Acinetobacter baylyi. One of these Tat pathways is essential for growth, while the other is not. We constructed a loss-of-function mutation to disrupt the non-essential tatC2 gene and assessed its contribution to cell growth under different environmental conditions. While the tatC2 mutant grew well under standard laboratory conditions, it displayed a growth defect and an aberrant cellular morphology when subjected to high temperature stress including an aberrant cellular morphology. Furthermore, increased sensitivities to detergent suggested a compromised cell envelope. Lastly, using an in vitro co-culture system, we demonstrate that the non-essential Tat pathway provides a growth advantage. The findings of this study establish the importance of the non-essential Tat pathway for optimal growth of A. baylyi in stressful environmental conditions.