Structural studies on the reaction of isopenicillin N synthase with the truncated substrate analogues delta-(L-alpha-aminoadipoyl)-L-cysteinyl-glycine and delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-alanine.

Long, A; Clifton, I; Roach, P; Baldwin, J; Rutledge, P; Schofield, C

Journal article

Structural studies on the reaction of isopenicillin N synthase with the truncated substrate analogues delta-(L-alpha-aminoadipoyl)-L-cysteinyl-glycine and delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-alanine.

Abstract:: Isopenicillin N synthase (IPNS), a non-heme iron(II)-dependent oxidase, catalyzes conversion of the tripeptide delta-(l-alpha-aminoadipoyl)-l-cysteinyl-d-valine (ACV) to bicyclic isopenicillin N (IPN), concomitant with the reduction of dioxygen to two molecules of water. Incubation of the "truncated"substrate analogues delta-(l-alpha-aminoadipoyl)-l-cysteinyl-glycine (ACG) and delta-(l-alpha-aminoadipoyl)-l-cysteinyl-d-alanine (ACA) with IPNS has previously been shown to afford acyclic products, in which the substrate cysteinyl residue has undergone a two-electron oxidation. We report X-ray crystal structures for the anaerobic IPNS/Fe(II)/ACG and IPNS/Fe(II)/ACA complexes, both in the absence and presence of the dioxygen analogue nitric oxide. The overall protein structures are very similar to those of the corresponding IPNS/Fe(II)/ACV complexes; however, significant differences are apparent in the vicinity of the active site iron. The structure of the IPNS/Fe(II)/ACG complex reveals that the C-terminal carboxylate of this substrate is oriented toward the active site iron atom, apparently hydrogen-bonded to an additional water ligand at the metal; this is a different binding mode to that observed in the IPNS/Fe(II)/ACV complex. ACA binds to the metal in a manner that is intermediate between those observed for ACV and ACG. The addition of NO to these complexes initiates conformational changes such that both the IPNS/Fe(II)/ACG/NO and IPNS/Fe(II)/ACA/NO structures closely resemble the IPNS/Fe(II)/ACV/NO complex. These results further demonstrate the feasibility of metal-centered rearrangements in catalysis by non-heme iron enzymes and provide insight into the delicate balance between hydrophilic-hydrophobic interactions and steric effects in the IPNS active site.

Publication status:: Published

Actions

Email

Email this record

Send the bibliographic details of this record to your email address.

Your Email
Please enter the email address that the record information will be sent to.

-
Your message (optional)
Please add any additional information to be included within the email.
Share
Cite

Cite this record

APA Style

Long, A., Clifton, I., Roach, P., Baldwin, J., Rutledge, P., & Schofield, C. (2005). Structural studies on the reaction of isopenicillin N synthase with the truncated substrate analogues delta-(L-alpha-aminoadipoyl)-L-cysteinyl-glycine and delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-alanine. Biochemistry, 44(17), 6619–6628.

MLA Style

Long, A, et al. “Structural Studies on the Reaction of Isopenicillin N Synthase with the Truncated Substrate Analogues Delta-(L-Alpha-Aminoadipoyl)-L-Cysteinyl-Glycine and Delta-(L-Alpha-Aminoadipoyl)-L-Cysteinyl-D-Alanine.” Biochemistry, vol. 44, no. 17, 2005, pp. 6619–28.

Chicago Style

Long, A, I Clifton, P Roach, J Baldwin, P Rutledge, and C Schofield. 2005. “Structural Studies on the Reaction of Isopenicillin N Synthase with the Truncated Substrate Analogues Delta-(L-Alpha-Aminoadipoyl)-L-Cysteinyl-Glycine and Delta-(L-Alpha-Aminoadipoyl)-L-Cysteinyl-D-Alanine.” Biochemistry 44 (17): 6619–28.
Print