Mechanism of Inactivation of Glutamine Amidotransferases

نویسندگان

  • J. Yun Tso
  • G. Bower
  • Howard Zalkin
چکیده

L-(aS, 5S)-a-Amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125), an antitumor drug isolated from Streptomyces sviceus, is an active site-directed affinity analog of glutamine, I t selectively inactivates the glutamine-dependent activities of two bacterial glutamine amidotransferases, anthranilate synthase and glutamate synthase. A reversible noncovalent complex is formed prior to irreversible enzyme modification. Inactivation of anthranilate synthase results from incorporation of approximately 1 eq of AT-l25/enzyme protomer. Active site cysteine-83 in Serratia marcescens anthranilate synthase Component I1 is the residue alkylated by AT-125. Anthranilate synthase is rapidly inactivated by AT-125 in S. marcescens cells. In vivo inactivation is by the same mechanism as in vitro.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Structures of glutamine amidotransferases from the purine biosynthetic pathway.

Introduction Glutamine is the source for most of the nitrogen in biosynthetic pathways because of its connection to carbohydrate metabolism via cr-oxoglutarate and glutamate. The enzymes that transfer nitrogen from the amide of glutamine to acceptor substrates in biosynthetic pathways are known as glutamine amidotransferases. Glutamine amidotransferases are a large and well studied family of en...

متن کامل

Catalysis uncoupling in a glutamine amidotransferase bienzyme by unblocking the glutaminase active site.

Nitrogen is incorporated into various metabolites by multifunctional glutamine amidotransferases via reactive ammonia generated by glutaminase hydrolysis of glutamine. Although this process is generally tightly regulated by subsequent synthase activity, little is known about how the glutaminase is inhibited in the absence of an activating signal. Here, we use imidazoleglycerolphosphate synthase...

متن کامل

Amino-terminal deletions define a glutamine amide transfer domain in glutamine phosphoribosylpyrophosphate amidotransferase and other PurF-type amidotransferases.

A series of deletions was constructed in cloned Escherichia coli purF encoding glutamine phosphoribosylpyrophosphate amidotransferase. These deletions extended into the NH2 terminus of the protein and removed amino acids that are required for glutamine-dependent enzyme activity. Enzyme function, ascribed to the NH3-dependent activity, was retained in deletions that removed up to 237 amino acids...

متن کامل

Structural evidence for ammonia tunneling across the (beta alpha)(8) barrel of the imidazole glycerol phosphate synthase bienzyme complex.

Since reactive ammonia is not available under physiological conditions, glutamine is used as a source for the incorporation of nitrogen in a number of metabolic pathway intermediates. The heterodimeric ImGP synthase that links histidine and purine biosynthesis belongs to the family of glutamine amidotransferases in which the glutaminase activity is coupled with a subsequent synthase activity sp...

متن کامل

Glutamine-binding subunit of glutamate synthase and partial reactions catalyzed by this glutamine amidotransferase.

In the course of studies on glutamine-dependent carbamyl phosphate synthetase from Aerobacter aerogenes, we purified another protein which was found to be glutamate synthase (EC 2.6.1.53). The enzyme, obtained in apparently homogeneous form (monomer molecular weight about 227,000; s(20,omega) = 17.6 S), was found to be a typical glutamine amidotransferase in that it exhibits glutaminase activit...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2001