4.3.1.B2: imidazole glycerol phosphate synthase

IGP synthases formed with Q123R mutant HisF subunit has no measurable activity with glutamine in vitro

E46G

IGP synthases formed with E46G mutant HisF subunit shows 2800fold reduction in the kcat/Km ratio for glutamine

Q123R

IGP synthases formed with Q123R mutant HisF subunit has no measurable activity with glutamine in vitro

R5H

IGP synthases formed with R5H mutant HisF subunit shows 1500fold reduction in the kcat/Km ratio for glutamine

D359A

2300fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: L-glutamine), 4fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 7.5fold decrease in kcat/Km of L-glutamine

K196A

0.43fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: L-glutamine), 1fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 3fold decrease in kcat/Km of L-glutamine

K196A/D359A

K258A

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 43:1 (wild-type ratio is 1:1), 2600fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 385fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 1055fold decrease in kcat/Km of L-glutamine

K258R

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 3:1 (wild-type ratio is 1:1), 20fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 125fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 45fold decrease in kcat/Km of L-glutamine

K360R

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 1:1 (identical to wild-type ratio), 1090fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 3.5fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 6.4fold decrease in kcat/Km of L-glutamine

N13A

130fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: L-glutamine), 3fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 350fold decrease in kcat/Km of L-glutamine

Q397A

7.5fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: L-glutamine), 1fold decrease in kcat/Km of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 18fold decrease in kcat/Km of L-glutamine

R239A

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 122:1 (wild-type ratio is 1:1), 860fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 5.4fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 3450fold decrease in kcat/Km of L-glutamine

R239H

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 154:1 (wild-type ratio is 1:1), 2400fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 5.2fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 1360fold decrease in kcat/Km of L-glutamine

R239K

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 40:1 (wild-type ratio is 1:1), 218fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 3.9fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 540fold decrease in kcat/Km of L-glutamine

R360A

ratio of glutamine turnover to N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate turnover is 3:1 (wild-type ratio is 1:1), 9.2fold decrease in kcat/KM of N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate L-glutamine), 1.4fold decrease in kcat/Km N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate (cosubstrate: NH4+), 15fold decrease in kcat/Km of L-glutamine

C9A

mutation in subunit HisF. Catalytic efficiencies kcat/Km of both isolated and complexed mutant subunit HisF is not significantly different from wild-type HisF

D11N

mutation in subunit HisF. Catalytic efficiency kcat/Km for N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate is decreased by approximately 5 orders of magnitude

D130N

the kcat value is reduced by a factor of about 400-500, and the Km for N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate is increased almost 20fold. Catalytic efficiency kcat/Km for N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate is decreased by approximately 5 orders of magnitude

D176N

mutation in subunit HisF. The variant tHisF_D176N shows a 40-50 fold decrease in kcat, both in isolated form and in complex with tHisH

D183N

mutation in subunit HisF. Catalytic efficiencies kcat/Km of both isolated and complexed mutant subunit HisF is not significantly different from wild-type HisF

D51N

mutation in subunit HisF. Catalytic efficiencies kcat/Km of both isolated and complexed mutant subunit HisF is not significantly different from wild-type HisF

K19S

mutation in subunit HisF. The ammonia-dependent reactions of isolated subunit HisF_K19S is similarly efficient as that of wild-type HisF. The efficiencies of the glutamine-dependent reactions of the tHisHtHisF_K19S complex are significantly impaired

N103A

mutation in subunit HisF. Catalytic efficiencies kcat/Km of both isolated and complexed mutant subunit HisF is not significantly different from wild-type HisF

T78M

the mutation does not impair substrate binding to the active site of HisF

728756

D130N

D176N

mutation in subunit HisF. The variant tHisF_D176N shows a 40-50 fold decrease in kcat, both in isolated form and in complex with tHisH

D183N

mutation in subunit HisF. Catalytic efficiencies kcat/Km of both isolated and complexed mutant subunit HisF is not significantly different from wild-type HisF

D51N