Oxidation of cytochrome 605 is the rate limiting step when Ferrimicrobium acidiphilum respires aerobically on soluble iron.

Oxidation of cytochrome 605 is the rate limiting step when Ferrimicrobium acidiphilum respires aerobically on soluble iron. Appl Environ Microbiol. 2020 Sep 11;: Authors: Blake RC, Guidry JJ, Anthony MD, Ban B, Smith KA, Walton NN, Painter RG Abstract Proteins that oxidize extracellular substrates in Gram-positive bacteria are poorly understood. Ferrimicrobium acidiphilum is an actinobacterium that respires aerobically on extracellular ferrous ions at pH 1.5. In situ absorbance measurements were conducted on turbid suspensions of intact Fm. acidiphilum using an integrating cavity absorption meter designed for that purpose. Initial velocity kinetic studies monitored the appearance of product ferric ions in the presence of catalytic quantities of cells. Cell-catalyzed iron oxidation obeyed the Michaelis-Menten equation with values for KM and Vmax of 71 μM and 0.29 fmol/min/cell, respectively. Limited-turnover kinetic studies were conducted with higher concentrations of cells to detect and monitor changes in the absorbance properties of cellular redox proteins when the cells were exposed to limited quantities of soluble reduced iron. A single a-type cytochrome with reduced absorbance peaks at 448 and 605 nm was the only redox-active chromophore that was visible as the cells respired aerobically on iron. The reduced cytochrome 605 exhibited mathematical and correlational properties that were consistent with the hypothesis that oxidation...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research