Effect of iron availability on the survival of carbapenem-resistant Acinetobacter baumannii: A proteomic approach

Abstract

Acinetobacter baumannii is a notorious pathogen and is known to cause hospital-acquired nosocomial infections. Presently, carbapenems are most effective antibiotics against A. baumannii, however, emerging carbapenem resistance by A. baumannii further made it difficult to treat the infections. One of the requirements of for successful invasion and colonization of A. baumannii is the essential micronutrient iron inside the human host. However, the bioavailability of iron is sequestered due to the nutritional immunity of host, which acts as an important virulence factor. Present study is an attempt to identify membrane proteins in response to in vitro iron-overload and iron-limiting conditions by using Differential In-Gel Electrophoresis (DIGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Carbapenem-resistant clinical strain of A. baumannii under iron-stress conditions, showed high expression of Fhu E receptor, ferric acinetobactin receptor, ferrienterchelin receptor, ferric siderophore receptor, bacterioferritin and cell division inhibitor suggesting their correlation in iron circumvention inside human host. On contrary, in presence of iron, proteins such as ATP synthase, malate dehydrogenase, acetyl-CoA carboxylase, ribosomal protein, EF-Ts etc are elevated indicating their role in facilitating the metabolism of carbohydrate, amino acid, fatty acid and nucleic acid. Present results indicate the adaptability of carbapenem-resistant A. baumannii to iron availability by differentially expressing some of its membrane proteins. © 2013 Tiwari V, et al.