page_title: Nik operon
section_title: Regulation of Ni2+ uptake
hierarchical_section_title: Nik operon / Regulation / Regulation of Ni2+ uptake
caption_attribution_description: English: Regulation of nickel ions in a cell through nik operon
context_page_description: The nik operon is an operon required for uptake of nickel ions into the cell. It is present in many bacteria, but has been extensively studied in Helicobacter pylori. Nickel is an essential nutrient for many microorganisms, where it participates in a variety of cellular processes. However, excessive levels of nickel ions in cell can be fatal to the cell. Nickel ion concentration in the cell is regulated through the nik operon.
context_section_description: Ni²⁺ is taken up into prokaryotic cells by one of two types of high-affinity transport systems. The first method involves ABC-type transporters (discussed in this article) and the second mechanism makes use of transition-metal permeases (such as HoxN of Ralstonia eutropha). The ABC-type transporter system consists of five proteins, NikA–E, that carry out the ATP-dependent transport of Ni²⁺. NikA is a soluble, periplasmic, Ni-binding protein; NikB and NikC form a transmembrane pore for passage of Ni; and NikD and NikE hydrolyze ATP and couple this energy to Ni²⁺-transport. When Ni²⁺ is available in excess, NikR protein represses transcription of nikABCDE.
caption: Regulation of nickel ion uptake by components of the nik operon
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