The influence of pH on Staphylococcus saprophyticus iron metabolism and the production of siderophores.

Abstract

Staphylococcus saprophyticus is a gram-positive coagulase negative bacteria which shows clinical importance due to its capability of causing urinary tract infections (UTI), as well as its ability to persist in this environment. Little is known about how S. saprophyticus adapts to the pH shift that occurs during infection. Thus, in this study we aim to use a proteomic approach to analyze the metabolic adaptations which occur as a response by S. saprophyticus when exposed to acid (5.5) and alkaline (9.0) pH environments. Proteins related to iron storage are overexpressed in acid pH, whilst iron acquisition proteins are overexpressed in alkaline pH. It likely occurs because iron is soluble at acid pH and insoluble at alkaline pH. To evaluate if S. saprophyticus synthesizes siderophores, CAS assays were performed, and the results confirmed their production. The chemical characterization of siderophores demonstrates that S. saprophyticus produces carboxylates derived from citrate. Of special note is the fact that citrate synthase (CS) is down-regulated during incubation at acid pH, corroborating this result. This data was also confirmed by enzymatic assay. Our results demonstrate that iron metabolism regulation is influenced by different pH levels, and show, for the first time, the production of siderophores by S. saprophyticus. Enzymatic assays suggest that citrate from the tricarboxylic acid cycle (TCA) is used as substrate for siderophore production.

• Authors: Bianca Silva Vieira de Souza, Karla Christina Sousa Silva, Ana Flávia Alves Parente, Clayton Luiz Borges, Juliano Domiraci Paccez, Maristela Pereira, Célia Maria de Almeida Soares, Marcia Giambiagi-deMarval, Mirelle Garcia Silva-Bailão, Juliana Alves Parente-Rocha
• Journal: Microbes and infection (Microbes Infect) Vol. 21 Issue 10 Pg. 456-463 (12 2019) ISSN: 1769-714X [Electronic] France
• PMID: 31075417 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2019 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Chemical References

• Carboxylic Acids
• Siderophores
• Citric Acid
• Iron
• Citrate (si)-Synthase

Topics

• Animals
• Carboxylic Acids (chemistry, metabolism)
• Cell Line
• Citrate (si)-Synthase (metabolism)
• Citric Acid (metabolism)
• Hydrogen-Ion Concentration
• Iron (metabolism)
• Iron Deficiencies
• Macrophages (microbiology)
• Mice
• Microbial Viability
• Operon (genetics)
• Proteomics
• Siderophores (chemistry, genetics, metabolism)
• Staphylococcus saprophyticus (genetics, growth & development, metabolism)