title: Regulation of glutamine synthetase activity by adenylylation in the Gram-positive bacterium Streptomyces cattleya.
abstract: The enzymatic activity of glutamine synthetase [GS; L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] from the Gram-positive bacterium Streptomyces cattleya is regulated by covalent modification. In whole cells containing high levels of GS the addition of ammonium chloride leads to a rapid decline in GS activity. Crude extracts prepared from such ammonia-shocked cells had very low levels of GS activity as measured by biosynthetic and gamma-glutamyltransferase assays. Incubation of the crude extracts with snake venom phosphodiesterase restored GS activity. In cell extracts, GS was also inactivated by an ATP- and glutamine-dependent reaction. Radioactive labeling studies demonstrated the incorporation of an AmP moiety into GS protein upon modification. Our results suggest a covalent modification of GS in a Gram-positive bacterium. This modification appears to be adenylylation of the GS subunit similar to that found in the Gram-negative bacteria.
mesh_terms: D000225:Adenine / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000643:Ammonium Chloride / Q000494:pharmacology; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D007527:Isoenzymes / Q000494:pharmacology; D043264:Phosphodiesterase I; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D013302:Streptomyces / Q000187:drug effects / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D000643:Ammonium Chloride; D005973:Glutamine; D000255:Adenosine Triphosphate; D010727:Phosphoric Diester Hydrolases; D043264:Phosphodiesterase I; C470790:phosphodiesterase I, snake venom; D005974:Glutamate-Ammonia Ligase; D000225:Adenine