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The first crystal structure of a eukaryotic PII protein has been solved by Mizuno et. al. [1] The structure reveals numerous plant-specific conserved characteristics that may lead to a better understanding of nitrogen metabolism in higher organisms.

The signal transduction protein PII, well known for being involved in regulating nitrogen metabolism, has been characterized in detail in prokaryotic organisms such as bacteria and archaea. As organisms evolve into more complex, higher life forms, the issue of regulating the incorporation of organic nitrogen remains an essential step in maintaining the necessary building blocks of life. The first eukaryotic PII protein structure, (Figure 1) from the model plant Arabidopsis thaliana, reveals interesting structural elements that are highly conserved among plants but absent from the well-studied prokaryotic PII proteins. Structural analysis suggests that the eukaryotic PII protein has acquired novel protein structures resulting in additional functions [1].

Figure 1. Ribbon diagram of A. thaliana PII bound to citrate. [1]

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Navigation links are at the top and bottom of every page. In the Background, Discovery and Implications sections, there are yellow sub topic links located just under the banner.

Background - important background information explaining the known prokaryotic nitrogen assimilation regulation pathway involving PII, specific information on PII's occurrence and structure, as well as a discussion of protein structural evolution.

Discovery - basic methods used in this study, and the important structural findings from Arabidopsis thaliana PII protein.

Implications - explains why these findings are important and discusses future research that will follow this discovery.

References - additional reading on this topic. Click on the blue highlighted reference number to obtain online access to the article.

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