TY - JOUR
T1 - The effects of iron limitation and cell density on prokaryotic metabolism and gene expression: Excerpts from Fusobacterium necrophorum strain 774 (sheep isolate)
AU - Antiabong, John
AU - Ball, Andrew
AU - Brown, Melissa
PY - 2015/5/25
Y1 - 2015/5/25
N2 - Fusobacterium necrophorum is a Gram-negative obligate anaerobe associated with several diseases in humans and animals. Despite its increasing clinical significance, there is little or no data on the relationship between its metabolism and virulence. Previous studies have shown that bacteria grown under iron-limitation express immunogenic antigens similar to those generated in vivo. Thus, this paper describes the relationship between F. necrophorum subsp. necrophorum (Fnn) metabolism and the expression of the encoded putative virulence factors under iron-restricted conditions. At the midlog phase, iron limitation reduced Fnn growth but the cell density was dependent on the size of the inoculum. Preferential utilization of glucose-1-phosphate, d-mannitol and l-phenylalanine; production of 2-hydroxycaproic acid and termination of dimethyl sulphide production were major Fnn response-factors to iron limitation. Ultimately, iron restriction resulted in an increased ability of Fnn to metabolize diverse carbon sources and in the expression of stress-specific virulence factors. Iron starvation in low Fnn cell density was associated with the up-regulation of haemagglutinin (HA) and leukotoxin (lktA) genes (2.49 and 3.72 fold change respectively). However, Fnn encoded Haemolysin (Hly), yebN homologue (febN) and tonB homologue, were down-regulated (0.15, 0.79 and 0.33, fold changes respectively). Interestingly, cell density appeared to play a regulatory role in the final bacteria cell biomass, induction of a metabolic gene expression and the expression pattern virulence factors in Fnn suggesting the role of a cell density-associated regulatory factor. This report suggest that future studies on differential expression of bacterial genes under altered environmental condition(s) should consider testing the effect of cell concentrations as this is often neglected in such studies. In conclusion, iron restriction induces preferential utilization of carbon sources and altered metabolism in Fnn with associated changes in the expression pattern of the virulence factors.
AB - Fusobacterium necrophorum is a Gram-negative obligate anaerobe associated with several diseases in humans and animals. Despite its increasing clinical significance, there is little or no data on the relationship between its metabolism and virulence. Previous studies have shown that bacteria grown under iron-limitation express immunogenic antigens similar to those generated in vivo. Thus, this paper describes the relationship between F. necrophorum subsp. necrophorum (Fnn) metabolism and the expression of the encoded putative virulence factors under iron-restricted conditions. At the midlog phase, iron limitation reduced Fnn growth but the cell density was dependent on the size of the inoculum. Preferential utilization of glucose-1-phosphate, d-mannitol and l-phenylalanine; production of 2-hydroxycaproic acid and termination of dimethyl sulphide production were major Fnn response-factors to iron limitation. Ultimately, iron restriction resulted in an increased ability of Fnn to metabolize diverse carbon sources and in the expression of stress-specific virulence factors. Iron starvation in low Fnn cell density was associated with the up-regulation of haemagglutinin (HA) and leukotoxin (lktA) genes (2.49 and 3.72 fold change respectively). However, Fnn encoded Haemolysin (Hly), yebN homologue (febN) and tonB homologue, were down-regulated (0.15, 0.79 and 0.33, fold changes respectively). Interestingly, cell density appeared to play a regulatory role in the final bacteria cell biomass, induction of a metabolic gene expression and the expression pattern virulence factors in Fnn suggesting the role of a cell density-associated regulatory factor. This report suggest that future studies on differential expression of bacterial genes under altered environmental condition(s) should consider testing the effect of cell concentrations as this is often neglected in such studies. In conclusion, iron restriction induces preferential utilization of carbon sources and altered metabolism in Fnn with associated changes in the expression pattern of the virulence factors.
KW - Differential expression
KW - Fusobacterium necrophorum
KW - Iron limitation
KW - Metabolite profile
KW - Virulence factors
UR - http://www.scopus.com/inward/record.url?scp=84926421489&partnerID=8YFLogxK
U2 - 10.1016/j.gene.2015.03.017
DO - 10.1016/j.gene.2015.03.017
M3 - Article
VL - 563
SP - 94
EP - 102
JO - Gene
JF - Gene
SN - 0378-1119
IS - 1
ER -