Sandbox Reserved 1053

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 aureus

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

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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 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+.

Zinc Binding

Residues involved in Zn 2+ binding

Zinc Ligand(s)

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