Mutational analysis of GstI protein, a glutamine synthetase translational inhibitor of Rhizobium leguminosarum

FEBS Letters

Manco, Giuseppe²  Napolitani, Chiara¹  Lamberti, Alessandro¹  Riccio, Anna¹  Mandrich, Luigi²  Patriarca, Eduardo J.¹ 

[1] Istituto di Genetica e Biofisica ‘A. Buzzati-Traverso’, CNR, Via Marconi 10, 80125 Naples, Italy;Istituto di Biochimica delle Proteine, CNR, Via P. Castellino 111, 80131 Naples, Italy

关键词: Glutamine synthetase;    Gene expression;    Post-transcriptional inhibition;    Alanine-scanning mutagenesis;   

DOI  :  10.1016/S0014-5793(03)01511-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The small GstI protein (63 amino acids) of Rhizobium leguminosarum inhibits the expression of the glnII (glutamine synthetase II) gene, thus reducing the bacterial ability to assimilate ammonium. In order to identify the residues essential for its inhibitory activity, all the 53 non-alanine amino acid residues of GstI were individually mutated into alanine. Based on their capacity to inhibit glnII expression (in two genetic backgrounds) three groups of mutants were identified. The first group displayed an inhibitory activity similar to the wild-type; the second and the third ones showed partial and total loss of inhibitory activity, respectively. Several mutations of the latter group concerned residues conserved in two related sequences from Sinorhizobium meliloti and Agrobacterium tumefaciens. Additionally, we performed experiments to exclude a GstI-mediated mechanism of glutamine synthetase II inhibition/degradation. Finally, the protein was over expressed in Escherichia coli, purified and characterised.

【 授权许可】

Unknown