Structure of Human Isovaleryl-CoA Dehydrogenase at 2.6 Å Resolution: Structural Basis for Substrate Specificity
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- 作者：Karen A. Tiffany ; David L. Roberts ; Ming Wang ; Rosemary Paschke ; Al-Walid A. Mohsen ; Jerry Vockley ; and Jung-Ja P. Kim
- 刊名：Biochemistry
- 出版年：1997
- 出版时间：July 15, 1997
- 年：1997
- 卷：36
- 期：28
- 页码：8455 - 8464
- 全文大小：302K
- 年卷期：v.36,no.28(July 15, 1997)
- ISSN：1520-4995
文摘
Isovaleryl-CoA dehydrogenase (IVD) belongs to animportant flavoprotein family of acyl-CoA dehydrogenases that catalyze the 
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-dehydrogenation of theirvarious thioester substrates. Althoughenzymes from this family share similar sequences, catalytic mechanisms,and structural properties, theposition of the catalytic base in the primary sequence is notconserved. E376 has been confirmed to bethe catalytic base in medium-chain (MCAD) and short-chain acyl-CoAdehydrogenases and is conservedin all members of the acyl-CoA dehydrogenase family except for IVD andlong-chain acyl-CoAdehydrogenase. To understand this dichotomy and to gain a betterunderstanding of the factors importantin determining substrate specificity in this enzyme family, thethree-dimensional structure of human IVDhas been determined. Human IVD expressed in Escherichiacoli crystallizes in the orthorhombic spacegroup P212121 with unitcell parameters a = 94.0 Å, b = 97.7 Å, andc = 181.7 Å. The structure of IVDwas solved at 2.6 Å resolution by the molecular replacement method andwas refined to an R-factor of20.7% with an Rfree of 28.8%. The overallpolypeptide fold of IVD is similar to that of othermembersof this family for which structural data are available. Thetightly bound ligand found in the active site ofthe structure of IVD is consistent with that of CoA persulfide.The identity of the catalytic base wasconfirmed to be E254, in agreement with previous molecular modeling andmutagenesis studies. Thelocation of the catalytic residue together with a glycine at position374, which is a tyrosine in all othermembers of the acyl-CoA dehydrogenase family, is important forconferring branched-chain substratespecificity to IVD.
,-dehydrogenation of theirvarious thioester substrates. Althoughenzymes from this family share similar sequences, catalytic mechanisms,and structural properties, theposition of the catalytic base in the primary sequence is notconserved. E376 has been confirmed to bethe catalytic base in medium-chain (MCAD) and short-chain acyl-CoAdehydrogenases and is conservedin all members of the acyl-CoA dehydrogenase family except for IVD andlong-chain acyl-CoAdehydrogenase. To understand this dichotomy and to gain a betterunderstanding of the factors importantin determining substrate specificity in this enzyme family, thethree-dimensional structure of human IVDhas been determined. Human IVD expressed in Escherichiacoli crystallizes in the orthorhombic spacegroup P212121 with unitcell parameters a = 94.0 Å, b = 97.7 Å, andc = 181.7 Å. The structure of IVDwas solved at 2.6 Å resolution by the molecular replacement method andwas refined to an R-factor of20.7% with an Rfree of 28.8%. The overallpolypeptide fold of IVD is similar to that of othermembersof this family for which structural data are available. Thetightly bound ligand found in the active site ofthe structure of IVD is consistent with that of CoA persulfide.The identity of the catalytic base wasconfirmed to be E254, in agreement with previous molecular modeling andmutagenesis studies. Thelocation of the catalytic residue together with a glycine at position374, which is a tyrosine in all othermembers of the acyl-CoA dehydrogenase family, is important forconferring branched-chain substratespecificity to IVD.