Expressed Soybean Leghemoglobin: Effect on Escherichia coli at Oxidative and Nitrosative Stress

Abstract

Leghemoglobin (Lb) is an oxygen-binding plant hemoglobin of legume nodules, which participates in the symbiotic nitrogen fixation process. Another way to obtain Lb is its expression in bacteria, yeasts, or other organisms. This is promising for both obtaining Lb in the necessary quantity and scrutinizing it in model systems, e.g., its interaction with reactive oxygen (ROS) and nitrogen (RNS) species. The main goal of the work was to study how Lb expression affected the ability of Escherichia coli cells to tolerate oxidative and nitrosative stress. The bacterium E. coli with the embedded gene of soybean leghemoglobin a contains this protein in an active oxygenated state. The interaction of the expressed Lb with oxidative and nitrosative stress inducers (nitrosoglutathione, tert-butyl hydroperoxide, and benzylviologen) was studied by enzymatic methods and spectrophotometry. Lb formed NO complexes with heme-nitrosylLb or nonheme iron-dinitrosyl iron complexes (DNICs). The formation of Lb-bound DNICs was also detected by low-temperature electron paramagnetic resonance spectroscopy. Lb displayed peroxidase activity and catalyzed the reduction of organic peroxides. Despite this, E. coli-synthesized Lb were more sensitive to stress inducers. This might be due to the energy demand required by the Lb synthesis, as an alien protein consumes bacterial resources and thereby decreases adaptive potential of E. coli.

Efficient Secretory Expression for Mammalian Hemoglobins in Pichia pastoris

“…The results showed that all synthesized mammalian hemoglobins displayed the characteristic spectra in the Soret band region, peaking at 410 nm. This spectral similarity is a ributed to heme moiety binding in globin components, which was consistent with the previous research (Figure 9A) [26,62]. It demonstrated that the activities of synthesized HBs were close to the native HBs, suggesting they are suitable for applications in food processing and biocatalytic processes.…”

Production and Analytical Aspects of Natural Pigments to Enhance Alternative Meat Product Color

“…Over 98% of the peptidases bound to the column and the LegH were recovered in the wash fraction, and subsequent ion-exchange chromatography of the wash fraction at pH 8.0 yielded several fractions [ 66 ]. The previous supporting literature indicated a successful extraction of LegH from soy roots [ 67 , 68 , 69 ].…”

Nodulation Experiment by Cross-Inoculation of Nitrogen-Fixing Bacteria Isolated from Root Nodules of Several Leguminous Plants

“…The cross-section of the root nodules collected from the infected G. max indicated the presence of leghemoglobin (hemeprotein). Leghemoglobin is a symbiotic hemoglobin protein that creates the anaerobic conditions inside the nodules which is necessary for the effective symbiotic nitrogen fixation [ 11 , 12 , 45 ].…”

“…The symbiotic microorganisms fix the nitrogen inside the nodules in the form of bacteroids, known as symbiosomes using the catalytic nitrogenase enzymes. They do this in the presence of leghemoglobin (symbiotic hemoglobin), a hemeprotein produced due to the symbiotic association between the bacteroids and legumes [ 11 , 12 ].…”