Sandbox Reserved 1625: Difference between revisions
From Proteopedia
Jump to navigationJump to search
No edit summary |
No edit summary |
||
| Line 3: | Line 3: | ||
<StructureSection load='6rx4' size='350' frame='true' side='right' caption='Cartoon representation of E. coli cytochrome bd-1 oxidase designed from [https://www.rcsb.org/structure/6RX4 PDB: 6RX4]. Blue= CydA; green= CydB; yellow= CydX; pink= CydS; gray = hemes and UQ-8.' scene='83/832931/Full/3'> | <StructureSection load='6rx4' size='350' frame='true' side='right' caption='Cartoon representation of E. coli cytochrome bd-1 oxidase designed from [https://www.rcsb.org/structure/6RX4 PDB: 6RX4]. Blue= CydA; green= CydB; yellow= CydX; pink= CydS; gray = hemes and UQ-8.' scene='83/832931/Full/3'> | ||
==Introduction== | ==Introduction== | ||
<scene name='83/832931/Full/4'>Cytochrome bd oxidases</scene> are quinol-dependent [https://en.wikipedia.org/wiki/Transmembrane_protein transmembrane] (Fig. 1) terminal [https://en.wikipedia.org/wiki/Oxidase oxidases] found exclusively in [https://en.wikipedia.org/wiki/Prokaryote prokaryotes].<ref name="Safarian">PMID: 27126043</ref> With a very high oxygen affinity, bd oxidases play a vital role in the [https://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation] pathway in both gram-positive and gram-negative bacteria. Cytochrome ''bd'' oxidase's responsibility in the oxidative phosphorylation pathway also allows it to act as a key survival factor in the bacterial stress response against antibacterial drugs <ref name="Safarian">PMID: 31604309</ref>, hypoxia, cyanide, [https://en.wikipedia.org/wiki/Nitric_oxide nitric oxide], and H<sub>2</sub>O<sub>2</sub><ref name="Harikishore">PMID: 31939065</ref>. With their essential roles in bacterial survival, | <scene name='83/832931/Full/4'>Cytochrome bd oxidases</scene> are quinol-dependent [https://en.wikipedia.org/wiki/Transmembrane_protein transmembrane] (Fig. 1) terminal [https://en.wikipedia.org/wiki/Oxidase oxidases] found exclusively in [https://en.wikipedia.org/wiki/Prokaryote prokaryotes].<ref name="Safarian">PMID: 27126043</ref> With a very high oxygen affinity, bd oxidases play a vital role in the [https://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation] pathway in both gram-positive and gram-negative bacteria. Cytochrome ''bd'' oxidase's responsibility in the oxidative phosphorylation pathway also allows it to act as a key survival factor in the bacterial stress response against antibacterial drugs <ref name="Safarian">PMID: 31604309</ref>, hypoxia, cyanide, [https://en.wikipedia.org/wiki/Nitric_oxide nitric oxide], and H<sub>2</sub>O<sub>2</sub><ref name="Harikishore">PMID: 31939065</ref>. With their essential roles in bacterial survival, ''bd'' oxidases have been pursued as ideal targets for antimicrobial drug development. <ref name="Boot">PMID: 28878275</ref> | ||
[[Image:Transmembrane_bd_ox.png|550 px|center|thumb|''Figure 1''. Cartoon model of cytochrome bd-oxidase in ''E. coli''. Dashed lines represent borders of [https://en.wikipedia.org/wiki/Cytoplasm cytoplasmic] and [https://en.wikipedia.org/wiki/Periplasm periplasmic] regions. A quinol bound in the periplasmic <scene name='83/832924/Q_loop/3'>Q-loop</scene> is [https://en.wikipedia.org/wiki/Redox oxidized] and releases protons into the periplasmic space, generating a [https://en.wikipedia.org/wiki/Electrochemical_gradient proton gradient]. Protons and oxygen atoms from the cytoplasmic side enter cytochrome ''bd'' oxidase through specific channels. Oxygen is [https://en.wikipedia.org/wiki/Redox reduced] to water, which is released into the cytoplasmic space. Blue = CydA; green = CydB; yellow = CydX; pink = CydS. [[https://www.rcsb.org/structure/6RX4 PDB: 6RX4]]]] | [[Image:Transmembrane_bd_ox.png|550 px|center|thumb|''Figure 1''. Cartoon model of cytochrome bd-oxidase in ''E. coli''. Dashed lines represent borders of [https://en.wikipedia.org/wiki/Cytoplasm cytoplasmic] and [https://en.wikipedia.org/wiki/Periplasm periplasmic] regions. A quinol bound in the periplasmic <scene name='83/832924/Q_loop/3'>Q-loop</scene> is [https://en.wikipedia.org/wiki/Redox oxidized] and releases protons into the periplasmic space, generating a [https://en.wikipedia.org/wiki/Electrochemical_gradient proton gradient]. Protons and oxygen atoms from the cytoplasmic side enter cytochrome ''bd'' oxidase through specific channels. Oxygen is [https://en.wikipedia.org/wiki/Redox reduced] to water, which is released into the cytoplasmic space. Blue = CydA; green = CydB; yellow = CydX; pink = CydS. [[https://www.rcsb.org/structure/6RX4 PDB: 6RX4]]]] | ||
The overall mechanism of ''bd'' oxidases involves an exergonic [https://en.wikipedia.org/wiki/Dioxygen_in_biological_reactions reduction of molecular oxygen] into water (Fig. 2). During this reaction, a proton gradient is generated in order to assist in the conservation of energy. <ref name="Belevich">PMID: 17690093</ref> Unlike other terminal oxidases, bd oxidases do not use a proton pump. Instead, bd oxidases use a form of vectorial chemistry that releases protons from the quinol oxidation into the positive, periplasmic side of the membrane. Protons that are required for the water formation are then consumed from the negative, cytoplasmic side of the membrane, thus creating the previously mentioned proton gradient. | The overall mechanism of ''bd'' oxidases involves an exergonic [https://en.wikipedia.org/wiki/Dioxygen_in_biological_reactions reduction of molecular oxygen] into water (Fig. 2). During this reaction, a proton gradient is generated in order to assist in the conservation of energy. <ref name="Belevich">PMID: 17690093</ref> Unlike other terminal oxidases, bd oxidases do not use a proton pump. Instead, bd oxidases use a form of vectorial chemistry that releases protons from the quinol oxidation into the positive, periplasmic side of the membrane. Protons that are required for the water formation are then consumed from the negative, cytoplasmic side of the membrane, thus creating the previously mentioned proton gradient. | ||
