Bacterial nitrous oxide respiration: electron transport chains and copper transfer reactions

2019 ◽  
pp. 137-175 ◽  
Author(s):  
Sascha Hein ◽  
Jörg Simon
Keyword(s):  
Nitrous Oxide ◽  
Electron Transport ◽  
Transfer Reactions ◽  
Electron Transport Chains ◽  
Nitrous Oxide Respiration ◽  
Copper Transfer

Keilin's Cytochromes: How Bacteria Use Them, Vary Them and Make Them

2001 ◽  
Vol 29 (6) ◽  
pp. 629-640 ◽  
Author(s):  
S. J. Ferguson
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Electron Transport ◽  
Polypeptide Chain ◽  
Transfer Reactions ◽  
Porphyrin Ring ◽  
Thiol Groups ◽  
Cell Respiration ◽  
Post Translational Modification ◽  
Nitrogen Gas

Many proteins with one or more haem groups bound per polypeptide chain are called cytochromes. They function in electron transfer reactions and some are involved directly in the catalysis of chemical reactions, most prominently the reduction of oxygen to water in the terminal step of cell respiration. When unmodified haem is present the cytochromes are referred to as b-type, but if the haem is covalently attached to thiol groups of a Cys-Xaa-Xaa-Cys-His motif then the cytochrome is a c-type. Neither the purpose of this post-translational modification, nor the mechanisms of the machineries that are necessary for formation of the thioether bonds between protein and haem, are fully understood. In bacteria the c-type cytochromes function in the periplasm where they are involved in a range of electron transport activities, including the reactions of denitrification, in which nitrate is reduced sequentially via nitrite, nitric oxide and nitrous oxide to nitrogen gas. Other types of cytochromes have haem molecules with modifications to their porphyrin ring. These include the a-, d-, d1- and o-types. Although Keilin first described the a-, b- and c- types of cytochrome more than 60 years ago, we still do not have clear explanations as to why one type of haem moiety does not suffice for the requirements of mitochondrial, thylakoid and bacterial electron transport.

The Perennial Riddle of Life’s Origin

2021 ◽  
pp. 82-96
Author(s):  
Franklin M. Harold
Keyword(s):  
Natural Selection ◽  
Electron Transport ◽  
Atp Synthase ◽  
Hydrothermal Vents ◽  
Rna World ◽  
Good Reason ◽  
Dynamic Network ◽  
Electron Transport Chains ◽  
The Origin Of Life

The origin of life is the most consequential problem in biology, possibly in all of science, and it remains unsolved. This chapter summarizes what has been learned and highlights questions that remain open, including How, Where, When, and especially Why. LUCA, some four billion years ago, already featured the basic capacities of contemporary cells. These must have evolved still earlier, at a nebulous proto-cellular stage. There is good reason to believe that enzymes, DNA, ribosomes, electron-transport chains, and the rotary ATP synthase all predate LUCA and were shaped by the standard process of variation and natural selection, but we know next to nothing about how cells ever got started. I favor the proposal that it began with a purely chemical dynamic network capable of reproducing itself, that may have originated by chance. Natural selection would have favored the incorporation of any ancillary factors that promoted its kinetic stability, especially ones that improved reproduction or gave access to energy. All the specifics are in dispute, including the role of a prebiotic broth of organic chemicals, the nature and origin of enclosure, the RNA world, and a venue in submarine hydrothermal vents. My sense is that critical pieces of the puzzle remain to be discovered.

High Oleic Sunflower: Studies on Composition and Desaturation of Acyl Groups in Different Lipids and Organs

1990 ◽  
Vol 45 (3-4) ◽  
pp. 166-172 ◽  
Author(s):  
Petra Sperling ◽  
Ute Hammer ◽  
Wolfgang Friedt ◽  
Ernst Heinz
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Electron Transport ◽  
Fatty Acid Profiles ◽  
High Oleic ◽  
Oleate Desaturase ◽  
Electron Transport Chains ◽  
Selection Of

Abstract A selection of lipids from achenes, cotyledons after germination, roots and leaves of normal and high oleic varieties of sunflower were analyzed with regard to their fatty acid profiles. The lipids included triacylglycerol and phosphatidylcholine as ER-made components and mono-and digalactosyl diacylglycerol as plastid-localized glycolipids. A comparison of fatty acid pat­ terns showed that the block in oleate desaturation of the high oleic variety is confined to the ER of fat accumulating embryos, but that upon germination the oleate desaturation in the cotyledonary ER is rapidly derepressed. These data are supported by enzymatic experiments. In microsomes from maturing fruits of the high oleic variety oleoyl-phosphatidylcholine desaturase could not be detected, whereas o leoyl-CoA : lyso-phosphatidylcholine acyltransferase and components of the microsomal electron transport chains were not affected. A correlation in the expression of desaturation blocks in seed and root fatty acids as observed in mutants of other species was not observed which, therefore, cannot be generalized. Our data are discussed in terms of the existence of two ER-specific oleate desaturase activities.

scholarly journals Lactobacillus plantarum WCFS1 Electron Transport Chains

2009 ◽  
Vol 75 (11) ◽  
pp. 3580-3585 ◽  
Author(s):  
R. J. W. Brooijmans ◽  
W. M. de Vos ◽  
J. Hugenholtz
Keyword(s):  
Electron Transport ◽  
Lactobacillus Plantarum ◽  
Consumption Rate ◽  
Growth Media ◽  
Terminal Electron Acceptor ◽  
Glucose Levels ◽  
Transport Chain ◽  
Electron Transport Chains ◽  
Cofactor Biosynthesis ◽  
Isogenic Mutants

ABSTRACT Lactobacillus plantarum WCFS1 requires both heme and menaquinone to induce respiration-like behavior under aerobic conditions. The addition of these compounds enhanced both biomass production, without progressive acidification, and the oxygen consumption rate. When both heme and menaquinone were present, L. plantarum WCFS1 was also able to reduce nitrate. The ability to reduce nitrate was severely inhibited by the glucose levels that are typically found in L. plantarum growth media (1 to 2% [vol/vol] glucose). In contrast, comparable mannitol levels did not inhibit the reduction of nitrate. L. plantarum reduced nitrate with concomitant formation of nitrite and ammonia. Genes that encode a bd-type cytochrome (cydABCD) and a nitrate reductase (narGHJI) were identified in the genome of L. plantarum. The narGHJI operon is part of a cluster of genes that includes the molybdopterin cofactor biosynthesis genes and narK. Besides a menaquinone source, isogenic mutants revealed that cydA and ndh1 are required for the aerobic-respiration-like response and narG for nitrate reduction. The ndh1 mutant was still able to reduce nitrate. The existence of a nonredundant branched electron transport chain in L. plantarum WCFS1 that is capable of using oxygen or nitrate as a terminal electron acceptor is proposed.

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