CHa-COO CH The side chain 0=C-COO Glutamine +H++NADPH amino group of a-Ketoglutarate glutamine is then e Glutamate synth transferred to al-ketoglutarate Glutamate +NADP+ CH- coo- to form Glu CH A HCNH3* COO L-Glutamate
e The side chain amino group of glutamine is then transferred to a-ketoglutarate to form Glu
5. The bacterial glutamine synthetase is a central control point in nitrogen metabolism The bacterial glutamine synthetase has 12 identical subunits(each having an E independent active site) arranged as, two hexagonal rings. s Each subunit of the enzyme is accumulatively inhibited by at least eight allosteric effectors
5. The bacterial Glutamine synthetase is a central control point in nitrogen metabolism • The bacterial glutamine synthetase has 12 identical subunits (each having an independent active site) arranged as two hexagonal rings. • Each subunit of the enzyme is accumulatively inhibited by at least eight allosteric effectors
In addition the enzyme is more susceptible to the allosteric inhibition by having Tyr397 due modified by adenylylation The addition and removal of the AMP group to the glutamine synthetase are catalyzed by two active sites of the same bifunctional adenylyltransferase (AT The substrate specificity of AT was found to be controlled by a regulatory protein, PIl
• In addition the enzyme is more susceptible to the allosteric inhibition by having Tyr397 residue modified by adenylylation. • The addition and removal of the AMP group to the glutamine synthetase are catalyzed by two active sites of the same bifunctional adenylyltransferase (AT). • The substrate specificity of AT was found to be controlled by a regulatory protein, PII
The activity of PIl, in turn, is regulated by the uridylylation of a specific Tyr residue: PII-UMP stimulates the adenylylation activity of at, however the unmodified Pll stimulates the deadenylylation activity of AT The addition and removal of ump to PIl in turn are again catalyzed by two active sites of the same protein,uridylyltransferase (UT): a-ketoglutarate and atp stimulate the uridylylation, however, GIn and Pi stimulate the deuridylylation(thus adenylylation of AT, inactivating glutamine synthetase)
• The activity of PII, in turn, is regulated by the uridylylation of a specific Tyr residue: PII-UMP stimulates the adenylylation activity of AT, however, the unmodified PII stimulates the deadenylylation activity of AT. • The addition and removal of UMP to PII, in turn, are again catalyzed by two active sites of the same protein, uridylyltransferase (UT): a-ketoglutarate and ATP stimulate the uridylylation, however, Gln and Pi stimulate the deuridylylation (thus adenylylation of AT, inactivating glutamine synthetase)
The bacterial glutamine synthetase has 12 subunits arranged as two rings of hexamers (a) Active sites Tyr397 (adenylylation site) (b)
The bacterial glutamine synthetase has 12 subunits arranged as two rings of hexamers Active sites Tyr397 (adenylylation site)