The Transcriptomic and Bioinformatic Characterizations of Iron Acquisition and Heme Utilization in Avibacterium paragallinarum in Response to Iron-Starvation

Abstract

Avibacterium paragallinarum is the pathogen of infectious coryza, which is a highly contagious respiratory disease of chickens that brings a potentially serious threat to poultry husbandry. Iron is an important nutrient for bacteria and can be obtained from surroundings such as siderophores and hemophores. To date, the mechanisms of iron acquisition and heme utilization as well as detailed regulation in A. paragallinarum have been poorly understood. In this study, we investigated the transcriptomic profiles in detail and the changes of transcriptomes induced by iron restriction in A. paragallinarum using RNA-seq. Compared with the iron-sufficiency control group, many more differentially expressed genes (DEGs) and cellular functions as well as signaling pathways were verified in the iron-restriction group. Among these DEGs, the majority of genes showed decreased expression and some were found to be uniquely present in the iron-restriction group. With an in-depth study of bioinformatic analyses, we demonstrated the crucial roles of the Hut protein and DUF domain-containing proteins, which were preferentially activated in bacteria following iron restriction and contributed to the iron acquisition and heme utilization. Consequently, RT-qPCR results further verified the iron-related DEGs and were consistent with the RNA-seq data. In addition, several novel sRNAs were present in A. paragallinarum and had potential regulatory roles in iron homeostasis, especially in the regulation of Fic protein to ensure stable expression. This is the first report of the molecular mechanism of iron acquisition and heme utilization in A. paragallinarum from the perspective of transcriptomic profiles. The study will contribute to a better understanding of the transcriptomic response of A. paragallinarum to iron starvation and also provide novel insight into the development of new antigens for potential vaccines against infectious coryza by focusing on these iron-related genes.

HutZ is required for efficient heme utilization and contributes to the pathogenicity of Avibacterium paragallinarum

“…Fortunately, we have also identified the HutZ protein in Av. paragallinarum based on RNA-seq analysis ( 25 ). Herein, we focused on the role of HutZ on growth and iron homeostasis in Av.…”

“…paragallinarum , our previous research has also identified the preferential expression of HutZ in bacteria under iron-restriction condition based on RNA-seq analysis and qPCR, speculating that heme transport system can play an essential role in iron acquisition and HutZ protein plays an essential role in iron homeostasis of Av. paragallinarum ( 25 ). Nevertheless, the mechanism of interaction between HutZ and Av.…”

A Novel Lateral Flow Assay for Rapid and Sensitive Nucleic Acid Detection of Avibacterium paragallinarum

“…The strain 221 of the Av. paragallinarum serogroup A was cultured as previously described (1). First of all, the colonies of bacterial strains were resuspended in sterile water at 30 µl and then were boiled for 10 min.…”

“…For clinical samples, the swabs from the infraorbital sinuses of the chickens with suspected infectious coryza were collected. They were inoculated in the tryptic soy broth agar plates that were added with 10% chicken serum and 0.0025% NAD as previously described (1). The plates were incubated and suspected colonies of Av.…”

“…Infectious coryza, caused by Gram-negative Avibacterium paragallinarum, is a severe respiratory disease of chickens that engenders huge economic losses for the poultry industry over the past decade (1,2). Based on two kinds of schemes-the Page scheme and the Kume scheme, Av.…”