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1wkm
From Proteopedia
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'''THE PRODUCT BOUND FORM OF THE MN(II)LOADED METHIONINE AMINOPEPTIDASE FROM HYPERTHERMOPHILE PYROCOCCUS FURIOSUS''' | '''THE PRODUCT BOUND FORM OF THE MN(II)LOADED METHIONINE AMINOPEPTIDASE FROM HYPERTHERMOPHILE PYROCOCCUS FURIOSUS''' | ||
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[[Category: Ruebush, S.]] | [[Category: Ruebush, S.]] | ||
[[Category: Swierczek, S I.]] | [[Category: Swierczek, S I.]] | ||
| - | [[Category: | + | [[Category: Souza, V M.D.]] |
| - | [[Category: | + | [[Category: Aminopeptidase]] |
| - | [[Category: | + | [[Category: Hyperthermophile]] |
| - | [[Category: | + | [[Category: Methionine complex]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 13:48:37 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 10:48, 3 May 2008
THE PRODUCT BOUND FORM OF THE MN(II)LOADED METHIONINE AMINOPEPTIDASE FROM HYPERTHERMOPHILE PYROCOCCUS FURIOSUS
Overview
Methionine aminopeptidases (MetAPs) are ubiquitous metallohydrolases that remove the N-terminal methionine from nascent polypeptide chains. Although various crystal structures of MetAP in the presence of inhibitors have been solved, the structural aspects of the product-bound step has received little attention. Both perpendicular- and parallel-mode electron paramagnetic resonance (EPR) spectra were recorded for the Mn(II)-loaded forms of the type-I (Escherichia coli) and type-II (Pyrococcus furiosus) MetAPs in the presence of the reaction product l-methionine (L-Met). In general, similar EPR features were observed for both [MnMn(EcMetAP-I)]-L-Met and [MnMn(PfMetAP-II)]-L-Met. The observed perpendicular-mode EPR spectra consisted of a six-line hyperfine pattern at g = 2.03 (A = 8.8 mT) with less intense signals with eleven-line splitting at g = 2.4 and 1.7 (A = 4.4 mT). The former feature results from mononuclear, magnetically isolated Mn(II) ions and this signal are 3-fold more intense in the [MnMn(PfMetAP-II)]-L-Met EPR spectrum than in the [MnMn(EcMetAP-I)]-L-Met spectrum. Inspection of the EPR spectra of both [MnMn(EcMetAP-I)]-L-Met and [MnMn(PfMetAP-II)]-L-Met at 40 K in the parallel mode reveals that the [Mn(EcMetAP-I)]-L-Met spectrum exhibits a well-resolved hyperfine split pattern at g = 7.6 with a hyperfine splitting constant of A = 4.4 mT. These data suggest the presence of a magnetically coupled dinuclear Mn(II) center. On the other hand, a similar feature was not observed for the [MnMn(PfMetAP-II)]-L-Met complex. Therefore, the EPR data suggest that L-Met binds to [MnMn(EcMetAP-I)] differently than [MnMn(PfMetAP-II)]. To confirm these data, the X-ray crystal structure of [MnMn(PfMetAP-II)]-L-Met was solved to 2.3 A resolution. Both Mn1 and Mn2 reside in a distorted trigonal bipyramidal geometry, but the bridging water molecule, observed in the [CoCo(PfMetAP-II)] structure, is absent. Therefore, L-Met binding displaces this water molecule, but the carboxylate oxygen atom of L-Met does not bridge between the two Mn(II) ions. Instead, a single carboxylate oxygen atom of L-Met interacts with only Mn1, while the N-terminal amine nitrogen atom binds to M2. This L-Met binding mode is different from that observed for L-Met binding [CoCo(EcMetAP-I)]. Therefore, the catalytic mechanisms of type-I MetAPs may differ somewhat from type-II enzymes when a dinuclear metalloactive site is present.
About this Structure
1WKM is a Single protein structure of sequence from Pyrococcus furiosus. Full crystallographic information is available from OCA.
Reference
EPR and X-ray crystallographic characterization of the product-bound form of the MnII-loaded methionyl aminopeptidase from Pyrococcus furiosus., Copik AJ, Nocek BP, Swierczek SI, Ruebush S, Jang SB, Meng L, D'souza VM, Peters JW, Bennett B, Holz RC, Biochemistry. 2005 Jan 11;44(1):121-9. PMID:15628852 Page seeded by OCA on Sat May 3 13:48:37 2008
