Identification of iron-acquisition proteins ofAvibacterium paragallinarum

Abstract

When Avibacterium paragallinarum reference strain 0083 (serovar A) was grown in an iron-restricted culture medium, the expression of the 60, 68 and 93 kDa outer membrane proteins increased as compared with normal media. Sera of chickens experimentally infected with Av. paragallinarum recognized these ironrestriction induced proteins, suggesting their expression in vivo. The three outer membrane proteins were identified as transferrin receptor and iron transport proteins by mass spectroscopy and a search in sequence databases. As these proteins have been reported to be regulated by the Fur protein in many bacteria, we investigated, through molecular methods, the presence of the fur gene in Av. paragallinarum. A candidate fur gene of Av. paragallinarum was amplified by polymerase chain reaction using complementary primers to conserved regions of fur gene sequences from members of the Pasteurellaceae family. The nucleotide sequence of the cloned gene, from ATG to TAA stop codon, was 453 base pairs in length and the deduced amino acid sequence showed 94% identity with Fur sequences of Actinobacillus pleuropneumoniae and Haemophilus ducreyi. The Av. paragallinarum deduced Fur protein (17.8 kDa) amino acid sequence contains the N-terminal helixÁturnÁhelix DNA-binding domain and the two iron-binding sites in the C-terminal end, typical of other described Fur proteins. The study of iron-restriction-induced proteins and the mechanism regulating their expression could lead to an understanding of the responses of Av. paragallinarum to survive in an iron-restricted environment on host mucosal surfaces.

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

“…As previously reported, perhaps reduction of global gene expression and induction of unique genes are also helpful for A. paragallinarum to enter stationary phase by ceasing growth and retaining survivability for a long time (Miksch and Dobrowolski, 1995). Notably, several upregulated genes are demonstrated to be able to facilitate A. paragallinarum to effectively obtain iron for their growth (Abascal et al, 2009). In our study, when bacteria are in an ironrestriction environment, these upregulated gene products that we found can also be helpful for the release of iron from iron-binding proteins and compounds, promoting the acquisition and use of more iron sources by bacteria.…”

“…The siderophore transport system, which is capable of acquiring free inorganic iron, consists of both siderophores and TonB-dependent transferrin receptors (TBDR) on the outer membrane of bacteria (Chu et al, 2010). In A. paragallinarum, Abascal et al (2009) have identified three upexpressed outer membrane proteins acting as transferrin receptor and iron transport proteins in bacteria cultured in iron-restricted medium, which are regulated by the Fur protein (Abascal et al, 2009). They speculate that these proteins are associated with the colonization of bacteria in an iron-limited host environment.…”

Development of a lateral flow test for the rapid detection of Avibacterium paragallinarum in chickens suspected of having infectious coryza

“…TonB-dependent transporters (TBDTs) are membrane proteins that have high affinity for iron, vitamin B 12 , siderophores and carbohydrates, which are important for bacteria. Iron is the main substrate for TBDTs, and it participates in many bacterial metabolic processes [7].…”