Biochemical and mutational analysis of glutamine synthetase type III from the rumen anaerobe Ruminococcus albus 8.

ABSTRACT: Two different genes encoding glutamine synthetase type I (GSI) and GSIII were identified in the genome sequence of R. albus 8. The identity of the GSIII protein was confirmed by the presence of its associated conserved motifs. The glnN gene, encoding the GSIII, was cloned and expressed in Escherichia coli BL21 cells. The recombinant protein was purified and subjected to biochemical and physical analyses. Subunit organization suggested a protein present in solution as both monomers and oligomers. Kinetic studies using the forward and the gamma-glutamyl transferase (gamma-GT) assays were carried out. Mutations that changed conserved glutamic acid residues to alanine in the four GSIII motifs resulted in drastic decreases in GS activity using both assays, except for an E380A mutation, which ra

SUBMITTER: Amaya KR 

PROVIDER: S-EPMC1272975 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature