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== Biological Function ==
== Biological Function ==
Czr A is a transcriptional repressor protein responsible for the regulation of the Chromosome Determined Zinc Responsible (Czr) operon. The Czr operon contains genes for the proteins Czr A and Czr B. Czr B is a Zinc transport protein which moves Zinc out of a cell. Czr A regulates this process by controlling the degree to which Czr B is expressed. When relatively low amounts of zinc are present in the cell Czr A will bind to DNA, inhibiting expression of Czr B, enabling the cell to retain Zinc. When high amounts of Zinc 2+ are present in the cell, each Czr A molecule binds two Zn 2+ ions, and forcing a conformational change. The zinc binding conformation of Czr A is not capable of binding to DNA, as the new conformation disrupts the DNA binding pocket. Conversely, the DNA binding conformation of Czr A does not allow for the binding of either Zn 2+ atom.  
Czr A is a transcriptional repressor protein responsible for the regulation of the Chromosome Determined Zinc Responsible (Czr) operon. The Czr operon contains genes for the proteins Czr A and Czr B. Czr B is a Zinc transport protein which moves Zn 2+ out of a cell. Czr A regulates this process by controlling the degree to which Czr B is expressed. When relatively low amounts of zinc are present in the cell Czr A will bind to DNA,preventing the progression of RNA polymerase and thus inhibiting expression of Czr B. Decreased expression of Czr B results in the ability of the cell to retain Zn 2+ more readily. Because Czr A and Czr B are transcribed as part of the same operon, there must be a way that Czr A is inhibited to allow full transcription of Czr B. Czr A is inhibited by the binding of two Zn 2+ ions, which is ideal considering that this mechanism allows for Zn 2+ concentration inside the cell to determine the need for Zn 2+ transport out of the cell. Zn 2+ competitively inhibits the binding of DNA to Czr A. Czr A has two distinct conformations, one of which binds Zn 2+ with very high affinity that has virtually no affinity towards DNA binding, the other having a high affinity for DNA binding but very little affinity for Zn 2+.
== Structural Overview ==
===DNA Binding ===
===DNA Binding ===
===Zinc Binding ===
===Zinc Binding ===

Revision as of 16:31, 14 March 2017

Figure Legend
This Sandbox is Reserved from 02/09/2015, through 05/31/2016 for use in the course "CH462: Biochemistry 2" taught by Geoffrey C. Hoops at the Butler University. This reservation includes Sandbox Reserved 1051 through Sandbox Reserved 1080.
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Czr A Staphylococcus aureusCzr A Staphylococcus aureus

<StructureSection load='2kjc' size='340' side='right' caption='Caption for this structure' scene=>

This is a default text for your page '. Click above on edit this page' to modify. Be careful with the < and > signs. You may include any references to papers as in: the use of JSmol in Proteopedia [1] or to the article describing Jmol [2] to the rescue.

Biological FunctionBiological Function

Czr A is a transcriptional repressor protein responsible for the regulation of the Chromosome Determined Zinc Responsible (Czr) operon. The Czr operon contains genes for the proteins Czr A and Czr B. Czr B is a Zinc transport protein which moves Zn 2+ out of a cell. Czr A regulates this process by controlling the degree to which Czr B is expressed. When relatively low amounts of zinc are present in the cell Czr A will bind to DNA,preventing the progression of RNA polymerase and thus inhibiting expression of Czr B. Decreased expression of Czr B results in the ability of the cell to retain Zn 2+ more readily. Because Czr A and Czr B are transcribed as part of the same operon, there must be a way that Czr A is inhibited to allow full transcription of Czr B. Czr A is inhibited by the binding of two Zn 2+ ions, which is ideal considering that this mechanism allows for Zn 2+ concentration inside the cell to determine the need for Zn 2+ transport out of the cell. Zn 2+ competitively inhibits the binding of DNA to Czr A. Czr A has two distinct conformations, one of which binds Zn 2+ with very high affinity that has virtually no affinity towards DNA binding, the other having a high affinity for DNA binding but very little affinity for Zn 2+.

DNA BindingDNA Binding

Zinc BindingZinc Binding

Zinc Ligand(s)Zinc Ligand(s)

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ReferencesReferences

  1. ↑ Hanson, R. M., Prilusky, J., Renjian, Z., Nakane, T. and Sussman, J. L. (2013), JSmol and the Next-Generation Web-Based Representation of 3D Molecular Structure as Applied to Proteopedia. Isr. J. Chem., 53:207-216. doi:http://dx.doi.org/10.1002/ijch.201300024
  2. ↑ Herraez A. Biomolecules in the computer: Jmol to the rescue. Biochem Mol Biol Educ. 2006 Jul;34(4):255-61. doi: 10.1002/bmb.2006.494034042644. PMID:21638687 doi:10.1002/bmb.2006.494034042644

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA, Ben Zercher, Geoffrey C. Hoops, Katelyn Baumer, Mary Liggett, Jakob Jozwiakowski
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