Characterization of a variant iron protein of nitrogenase that is impaired in its ability to adopt the MgATP-induced conformational change.

The Journal of Biological Chemistry
E H Bursey, B K Burgess

Abstract

An Azotobacter vinelandii nitrogenase iron protein mutant has been created which contains an alanine to glycine substitution at amino acid 157. The strain expressing this mutant Fe protein is able to grow under nitrogen-fixing conditions. This contrasts with an A. vinelandii strain described previously which is unable to grow under nitrogen-fixing conditions and which expresses an Fe protein variant that has an alanine to serine mutation at position 157. The A157S Fe protein was unable to support substrate reduction by nitrogenase because of an inability to undergo a required MgATP-induced conformational change. Although the A157G strain grows at 55% of the rate of the wild-type strain, purified A157G Fe protein is only able to support substrate reduction in in vitro assays at a rate that is approximately 20% of the rate supported by the wild-type Fe protein. Electron paramagnetic resonance, circular dichroism spectroscopies, and enzymatic activity data indicate that the A157G Fe protein adopts the correct conformation upon the binding of MgATP. However, kinetic studies using chelation show that this protein undergoes the conformational change more slowly than the wild-type protein. Thus, this mutant has lower activity because ...Continue Reading

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Citations

Oct 16, 2009·Proceedings of the National Academy of Sciences of the United States of America·Chi Chung LeeMarkus W Ribbe
May 10, 2011·Proceedings of the National Academy of Sciences of the United States of America·Jared A WiigMarkus W Ribbe
Sep 29, 2012·Science·Jared A WiigMarkus W Ribbe
May 2, 2001·Proceedings of the National Academy of Sciences of the United States of America·M W Ribbe, B K Burgess
Feb 25, 2005·Proceedings of the National Academy of Sciences of the United States of America·Yilin HuMarkus W Ribbe
Sep 17, 2005·Proceedings of the National Academy of Sciences of the United States of America·Yilin HuMarkus W Ribbe
Jan 5, 2007·Journal of Biological Inorganic Chemistry : JBIC : a Publication of the Society of Biological Inorganic Chemistry·Yilin HuMarkus W Ribbe
Feb 24, 2009·Journal of Biological Inorganic Chemistry : JBIC : a Publication of the Society of Biological Inorganic Chemistry·Patrick Clark HallenbeckRoger N F Thorneley
Oct 29, 1998·The Journal of Biological Chemistry·E H Bursey, B K Burgess
Apr 8, 2015·The Biochemical Journal·Jackson K B CahnFrances H Arnold

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