Analysis of heme-binding proteins from Listeria monocytogenes using differential scanning calorimetry

Abstract

Listeria monocytogenes is a gram-positive bacterium that can cause severe infection in immunocompromised individuals. It is reliant on the acquisition of iron from its host to continuously spread throughout the body. Here we describe the thermal denaturation points of heme binding proteins Hbp1 and Hbp2, two iron scavenging proteins, using Differential Scanning Calorimetry. DSC is a useful technique used to characterize the thermal denaturation point of protein folding and unfolding events. As a result, the enthalpy and entropy of the protein unfolding event can be calculated. Conventional DSC results showed a reproducible denaturation point of 59.6 +/- 0.3 °C for Hbp1 and a denaturation point of 65.6 +/- 0.2 °C for Hbp2. Further investigation was completed to determine the role of bound ligands, such as heme, on overall protein stability. These thermodynamic values for protein denaturation can be applied to pharmaceutical studies to understand the role of these proteins as virulence factors for disease and their potential use as therapeutic targets.