Sandbox Reserved 335

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 22: Line 22:
<Structure load='3cp5' size='300' frame='true' align='right' caption='Insert caption here' scene='Sandbox_Reserved_335/Heme/1' />
<Structure load='3cp5' size='300' frame='true' align='right' caption='Insert caption here' scene='Sandbox_Reserved_335/Heme/1' />
-
All members in the C-type cytochrome superfamily contain a heme prosthetic group that is covalently attached to the protein via two thioether bonds to cysteine residues; most cytochromes ''c'' occur in a <scene name='Sandbox_Reserved_335/Motif/2'>CXXCH motif</scene>, where a histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> The other axial position, in monoheme cytochromes ''c'', may be left vacant or be occupied by histidine or methionine residues, but can sometimes be occupied by cysteine or leucine residues.<ref name=main />. The typical monoheme cyt ''c'' fold is formed by helices <scene name='Sandbox_Reserved_335/Helices/3'>A, C, and E</scene>. In ''Rm''cyt''c'' there are seven α-helices that are folded around the porphyrin ring, all connected by random coils.<ref name=main />
+
All members in the C-type cytochrome superfamily contain a heme prosthetic group that is covalently attached to the protein via two thioether bonds to cysteine residues; most cytochromes ''c'' occur in a <scene name='Sandbox_Reserved_335/Motif/1'>CXXCH motif</scene>, where a histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> The other axial position, in monoheme cytochromes ''c'', may be left vacant or be occupied by histidine or methionine residues, but can sometimes be occupied by cysteine or leucine residues.<ref name=main />. The typical monoheme cyt ''c'' fold is formed by helices <scene name='Sandbox_Reserved_335/Helices/3'>A, C, and E</scene>. In ''Rm''cyt''c'' there are seven α-helices that are folded around the porphyrin ring, all connected by random coils.<ref name=main />
-
In ''Rm''cyt''c'', the porphyrin ring is axially coordinated by <scene name='Sandbox_Reserved_335/Axial/4'>His49 and Met100</scene>
+
In ''Rm''cyt''c'', the porphyrin ring is axially coordinated by <scene name='Sandbox_Reserved_335/Axial/3'>His49 and Met100</scene>
Monoheme cytochromes ''c'' are involved in electron transport chains in both prokaryotes and eukaryotic mitochondria.<ref name=main /> They mediate the transfer of electrons mainly from the ''bc''<sub>1</sub> complexes, or their analogs, in the [http://en.wikipedia.org/wiki/Electron_transport_chain electron transport chain] to heme-copper oxygen reductases (HCOs) during [http://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation]. Heme ''c'' containing domains are often found fused to other protein domains such as these HCOs, including the ''caa''<sub>3</sub> oxygen reductases<ref name=main /><ref>PMID:14691678</ref>; these enzymes are membrane-bound and catalyze the reduction of O<sub>2</sub> to water.<ref>PMID:11334784</ref> In addition to being involved in the electron transport systems in oxidative phosphorylation, monoheme cyt ''c'' has also been seen to participate in the electron transport chain of [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis].<ref name=main />
Monoheme cytochromes ''c'' are involved in electron transport chains in both prokaryotes and eukaryotic mitochondria.<ref name=main /> They mediate the transfer of electrons mainly from the ''bc''<sub>1</sub> complexes, or their analogs, in the [http://en.wikipedia.org/wiki/Electron_transport_chain electron transport chain] to heme-copper oxygen reductases (HCOs) during [http://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation]. Heme ''c'' containing domains are often found fused to other protein domains such as these HCOs, including the ''caa''<sub>3</sub> oxygen reductases<ref name=main /><ref>PMID:14691678</ref>; these enzymes are membrane-bound and catalyze the reduction of O<sub>2</sub> to water.<ref>PMID:11334784</ref> In addition to being involved in the electron transport systems in oxidative phosphorylation, monoheme cyt ''c'' has also been seen to participate in the electron transport chain of [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis].<ref name=main />

Revision as of 21:00, 1 April 2011

This Sandbox is Reserved from January 10, 2010, through April 10, 2011 for use in BCMB 307-Proteins course taught by Andrea Gorrell at the University of Northern British Columbia, Prince George, BC, Canada.
To get started:
  • Click the edit this page tab at the top. Save the page after each step, then edit it again.
  • Click the 3D button (when editing, above the wikitext box) to insert Jmol.
  • show the Scene authoring tools, create a molecular scene, and save it. Copy the green link into the page.
  • Add a description of your scene. Use the buttons above the wikitext box for bold, italics, links, headlines, etc.

More help: Help:Editing


PDB ID 3cp5

Drag the structure with the mouse to rotate
3cp5, resolution 1.24Å ()
Ligands: ,
Gene: cytC (Rhodothermus marinus)
Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml



Cytochrome c (cyt c) is a superfamily of proteins belonging to the class of all-α proteins with a core of helices and a covalently-bound heme prosthetic group.[1][2] The cytochrome c superfamily contains many different families including monodomain and multi-domain C-type cytochromes (ex. cyt c4, a diheme C-type cytochrome, and NrfB, a pentaheme C-type cytochrome). This page focuses mainly on the cytochrome c superfamily, briefly discussing various types within the superfamily. The monoheme cytochrome c purified from Rhodothermus marinus will be discussed in greater detail than other C-type cytochromes.

Contents

Introduction

Cytochromes are a class of heme-containing proteins that are generally membrane-bound. They are soluble proteins[2] found in bacteria and the mitochondria of eukaryotic organisms, and are known as respiratory pigments because they are involved in electron transfer in various electron transport chains.[3] Cytochromes can be categorized into three different types, all based on the type of prosthetic heme group the cytochrome contains. Cytochrome c is named such because it contains the heme c, which is distinguished from hemes a, b, and d by its coordination to the protein scaffold by cysteinyl residues.[3]

Cyt c has been split into four classes[4], Class I containing single domain C-type cytochromes of which there has been at least six classes found in prokaryotes such as Desulfovibrio desulfuricans, Rhodospirillum rubrum, and Rhodothermus marinus.

Rhodothermus marinus

Rhodothermus marinus is a Gram-negative bacterium in the class Sphingobacteria, in phylum Bacteroidetes. These bacteria are thermophilic, obligate aerobes that have been previously isolated from shallow-water submarine hot springs located in Iceland.[5] A monoheme cytochrome c that has been thought to be the first member of a new class of cyt c was recently purified from R. marinus, having the nomenclature Rmcytc.[2]

Structure

Insert caption here

Drag the structure with the mouse to rotate

All members in the C-type cytochrome superfamily contain a heme prosthetic group that is covalently attached to the protein via two thioether bonds to cysteine residues; most cytochromes c occur in a , where a histidine residue is one of the two axial ligands of the heme iron.[2][3] The other axial position, in monoheme cytochromes c, may be left vacant or be occupied by histidine or methionine residues, but can sometimes be occupied by cysteine or leucine residues.[2]. The typical monoheme cyt c fold is formed by helices . In Rmcytc there are seven α-helices that are folded around the porphyrin ring, all connected by random coils.[2]

In Rmcytc, the porphyrin ring is axially coordinated by

Monoheme cytochromes c are involved in electron transport chains in both prokaryotes and eukaryotic mitochondria.[2] They mediate the transfer of electrons mainly from the bc1 complexes, or their analogs, in the electron transport chain to heme-copper oxygen reductases (HCOs) during oxidative phosphorylation. Heme c containing domains are often found fused to other protein domains such as these HCOs, including the caa3 oxygen reductases[2][6]; these enzymes are membrane-bound and catalyze the reduction of O2 to water.[7] In addition to being involved in the electron transport systems in oxidative phosphorylation, monoheme cyt c has also been seen to participate in the electron transport chain of photosynthesis.[2]

Mechanism

Importance

References

  1. ↑ Gough J, Karplus K, Hughey R, Chothia C. Assignment of homology to genome sequences using a library of hidden Markov models that represent all proteins of known structure. J Mol Biol. 2001 Nov 2;313(4):903-19. PMID:11697912 doi:10.1006/jmbi.2001.5080
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Stelter M, Melo AM, Pereira MM, Gomes CM, Hreggvidsson GO, Hjorleifsdottir S, Saraiva LM, Teixeira M, Archer M. A Novel Type of Monoheme Cytochrome c: Biochemical and Structural Characterization at 1.23 A Resolution of Rhodothermus marinus Cytochrome c. Biochemistry. 2008 Oct 15. PMID:18855424 doi:10.1021/bi800999g
  3. ↑ 3.0 3.1 3.2 Reedy CJ, Gibney BR. Heme protein assemblies. Chem Rev. 2004 Feb;104(2):617-49. PMID:14871137 doi:10.1021/cr0206115
  4. ↑ Ambler RP. Sequence variability in bacterial cytochromes c. Biochim Biophys Acta. 1991 May 23;1058(1):42-7. PMID:1646017
  5. ↑ Alfredsson GA, Kristjansson JK, Hjörleifsdottir S, Stetter, KO. Rhodothermus marinus, gen. nov., sp. nov., a thermophilic, halophilic bacterium from submarine hot springs in Iceland. J Gen Microbiol. 1988 Feb;134(2):299-306.
  6. ↑ Soares CM, Baptista AM, Pereira MM, Teixeira M. Investigation of protonatable residues in Rhodothermus marinus caa3 haem-copper oxygen reductase: comparison with Paracoccus denitrificans aa3 haem-copper oxygen reductase. J Biol Inorg Chem. 2004 Mar;9(2):124-34. Epub 2003 Dec 23. PMID:14691678 doi:10.1007/s00775-003-0509-9
  7. ↑ Pereira MM, Santana M, Teixeira M. A novel scenario for the evolution of haem-copper oxygen reductases. Biochim Biophys Acta. 2001 Jun 1;1505(2-3):185-208. PMID:11334784
Retrieved from "http://52.214.119.220/wiki/index.php/Sandbox_Reserved_335"
Personal tools