Journal Article

Function and Regulation of the Pyruvate Transporter CstA in Escherichia coli

Jung, Kirsten, Forné, Ignasi, Gasperotti, Ana, Göing, Stephanie, Fajardo-Ruiz, Elena

2020

Overview

Pyruvate is a central metabolite that connects many metabolic pathways in living organisms. To meet the cellular pyruvate requirements, the enterobacterium Escherichia coli has at least three pyruvate uptake systems—the H+/pyruvate symporter BtsT, and two thus far less well-characterized transporters, YhjX and CstA. BtsT and CstA belong to the putative carbon starvation (CstA) family (transporter classification TC# 2.A.114). We have created an E. coli mutant that cannot grow on pyruvate as the sole carbon source and used it to characterize CstA as a pyruvate transporter. Transport studies in intact cells confirmed that CstA is a highly specific pyruvate transporter with moderate affinity and is energized by a proton gradient. When cells of a reporter strain were cultured in complex medium, cstA expression was maximal only in stationary phase. A DNA affinity-capture assay combined with mass spectrometry and an in-vivo reporter assay identified Fis as a repressor of cstA expression, in addition to the known activator cAMP-CRP. The functional characterization and regulation of this second pyruvate uptake system provides valuable information for understanding the complexity of pyruvate sensing and uptake in E. coli.

• Publisher: MDPI AG,MDPI
• Subject: Amino acids / Base Sequence / Binding sites / Biological Transport / Carbon / Chemotaxis / E coli / Escherichia coli - genetics / Escherichia coli - growth & development / Escherichia coli - metabolism / Escherichia coli Proteins - genetics / Escherichia coli Proteins - metabolism / Gene expression / Glucose / Kinases / Metabolism / Metabolites / Mutation - genetics / Peptides / Phenotype / Promoter Regions, Genetic - genetics / Protein Binding / Pyruvic Acid - metabolism / Trans-Activators - genetics / Trans-Activators - metabolism