Heme biosynthesis is coupled to electron transport chains for energy generation

Abstract

Cellular energy generation uses membrane-localized electron transfer chains for ATP synthesis. Formed ATP in turn is consumed for the biosynthesis of cellular building blocks. In contrast, heme cofactor biosynthesis was found driving ATP generation via electron transport after initial ATP consumption. The FMN enzyme protoporphyrinogen IX oxidase (HemG) of Escherichia coli abstracts six electrons from its substrate and transfers them via ubiquinone, cytochrome bo 3 (Cyo) and cytochrome bd (Cyd) oxidase to oxygen. Under anaerobic conditions electrons are transferred via menaquinone, fumarate (Frd) and nitrate reductase (Nar). Cyo, Cyd and Nar contribute to the proton motive force that drives ATP formation. Four electron transport chains from HemG via diverse quinones to Cyo, Cyd, Nar, and Frd were reconstituted in vitro from purified components. Characterization of E. coli mutants deficient in nar, frd, cyo, cyd provided in vivo evidence for a detailed model of heme biosynthesis coupled energy generation.anabolism coupled catabolism | protoporphyrinogen IX oxidase | HemG | tetrapyrrole | respiration

Proteomics Analyses ofBacillus subtilisafter Treatment with Plumbagin, a Plant-Derived Naphthoquinone

“…TCA is the prime pathway to generate the majority of reducing equivalents (i.e., NADH in cell) and generates the proton motive force or membrane potential across the membrane essential for ATP synthesis (Möbius et al, 2010). Our results indicate that plumbagin treatment significantly repressed TCA and the electron transport chain, which indicates the blockage in energy generation.…”

The Chlorite Dismutase (HemQ) from Staphylococcus aureus Has a Redox-sensitive Heme and Is Associated with the Small Colony Variant Phenotype

“…The latter molecule is a primary electron carrier in the respiratory electron transport chain. Heme auxotrophy is believed to exert its influence on colony size (and bacterial doubling time) via the loss of respiration-associated cytochromes and terminal reductases (69). We therefore compared the ⌬hemQ and hemB growth phenotypes in the liquid phase under aerobic and anaerobic (fermentative) conditions, observing significantly slowed growth and attenuated final culture densities for the mutants specifically in the aerobic case (Fig.…”

Mutations in hemG Mediate Resistance to Salicylidene Acylhydrazides, Demonstrating a Novel Link between Protoporphyrinogen Oxidase (HemG) and Chlamydia trachomatis Infectivity

“…Thus, HemG activity is indirectly coupled to respiration. In Escherichia coli it has been suggested that HemG activity also has a direct role in respiration (59,60). At this stage, it is unclear how the specific hemG mutations identified provide resistance to IS-INP0341.…”