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Interactions between the nitrogen signal transduction protein PII and N-acetyl glutamate kinase in organisms that perform oxygenic photosynthesis.

ABSTRACT: PII, one of the most conserved signal transduction proteins, is believed to be a key player in the coordination of nitrogen assimilation and carbon metabolism in bacteria, archaea, and plants. However, the identity of PII receptors remains elusive, particularly in photosynthetic organisms. Here we used yeast two-hybrid approaches to identify new PII receptors and to explore the extent of conservation of PII signaling mechanisms between eubacteria and photosynthetic eukaryotes. Screening of Synechococcus sp. strain PCC 7942 libraries with PII as bait resulted in identification of N-acetyl glutamate kinase (NAGK), a key enzyme in the biosynthesis of arginine. The integrity of Ser49, a residue conserved in PII proteins from organisms that perform oxygenic photosynthesis, appears to be essential for NAGK binding. The effect of glnB mutations on NAGK activity is consistent with positive regulation of NAGK by PII. Phylogenetic and yeast two-hybrid analyses strongly suggest that there was conservation of the NAGK-PII regulatory interaction in the evolution of cyanobacteria and chloroplasts, providing insight into the function of eukaryotic PII-like proteins.

SUBMITTER: Burillo S

PROVIDER: S-EPMC415743 | biostudies-literature | 2004 Jun

REPOSITORIES: biostudies-literature

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Interactions between the nitrogen signal transduction protein PII and N-acetyl glutamate kinase in organisms that perform oxygenic photosynthesis.

Burillo Sergio S Luque Ignacio I Fuentes Inmaculada I Contreras Asunción A

Journal of bacteriology 20040601 11

PII, one of the most conserved signal transduction proteins, is believed to be a key player in the coordination of nitrogen assimilation and carbon metabolism in bacteria, archaea, and plants. However, the identity of PII receptors remains elusive, particularly in photosynthetic organisms. Here we used yeast two-hybrid approaches to identify new PII receptors and to explore the extent of conservation of PII signaling mechanisms between eubacteria and photosynthetic eukaryotes. Screening of Synec ...[more]

PMID: 15150219

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Project description:PII signal transduction proteins are ubiquitous and highly conserved in bacteria, archaea, and plants and play key roles in controlling nitrogen metabolism. However, research on biological functions and regulatory targets of PII proteins remains limited. Here, we illustrated experimentally that the PII protein Corynebacterium glutamicum GlnK (CgGlnK) increased l-arginine yield when glnK was overexpressed in Corynebacterium glutamicum Data showed that CgGlnK regulated l-arginine biosynthesis by upregulating the expression of genes of the l-arginine metabolic pathway and interacting with N-acetyl-l-glutamate kinase (CgNAGK), the rate-limiting enzyme in l-arginine biosynthesis. Further assays indicated that CgGlnK contributed to alleviation of the feedback inhibition of CgNAGK caused by l-arginine. In silico analysis of the binding interface of CgGlnK-CgNAGK suggested that the B and T loops of CgGlnK mainly interacted with C and N domains of CgNAGK. Moreover, F11, R47, and K85 of CgGlnK were identified as crucial binding sites that interact with CgNAGK via hydrophobic interaction and H bonds, and these interactions probably had a positive effect on maintaining the stability of the complex. Collectively, this study reveals PII-NAGK interaction in nonphotosynthetic microorganisms and further provides insights into the regulatory mechanism of PII on amino acid biosynthesis in corynebacteria.IMPORTANCE Corynebacteria are safe industrial producers of diverse amino acids, including l-glutamic acid and l-arginine. In this study, we showed that PII protein GlnK played an important role in l-glutamic acid and l-arginine biosynthesis in C. glutamicum Through clarifying the molecular mechanism of CgGlnK in l-arginine biosynthesis, the novel interaction between CgGlnK and CgNAGK was revealed. The alleviation of l-arginine inhibition of CgNAGK reached approximately 48.21% by CgGlnK addition, and the semi-inhibition constant of CgNAGK increased 1.4-fold. Furthermore, overexpression of glnK in a high-yield l-arginine-producing strain and fermentation of the recombinant strain in a 5-liter bioreactor led to a remarkably increased production of l-arginine, 49.978 g/liter, which was about 22.61% higher than that of the initial strain. In conclusion, this study provides a new strategy for modifying amino acid biosynthesis in C. glutamicum.

Dataset Information

Interactions between the nitrogen signal transduction protein PII and N-acetyl glutamate kinase in organisms that perform oxygenic photosynthesis.

Publications

Interactions between the nitrogen signal transduction protein PII and N-acetyl glutamate kinase in organisms that perform oxygenic photosynthesis.

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