The effects of long-term exposure (5 h) of Phycomyces blakesleeanus mycelium
to 5 mM KCN on respiration and phosphate metabolites were tested. Exposure to
cyanide, antimycin A and azide lead to a decrease in the activity of
cyanide-sensitive respiration (CSR), and the ratio of core polyphosphates
(PPc) and inorganic phosphates (Pi), which is a good indicator of the
metabolic state of a cell. After 5 h of incubation, the activity of CSR
returned to control values. For this, the recovery of cytochrome c oxidase
(COX) was required. In addition, the PPc/Pi ratio started to recover shortly
after initiation of COX recovery, but never reached control values. This led
us to conclude that the regulation of polyphosphate (PPn) levels in the cell
is tightly coupled to respiratory chain functioning. In addition, acutely
applied cyanide caused two different responses, observed by 31P NMR
spectroscopy, that were probably mediated through the mechanism of glycolytic
oscillations, triggered by the effect of cyanide on mitochondria.
Effect of long-term cyanide exposure on cyanide-sensitive respiration and phosphate metabolism in the fungus Phycomyces blakesleeanus