Spectroscopic characterization of a high-potential lipo-cupredoxin found in Streptomyces coelicolor.
J Am Chem Soc
; 128(45): 14579-89, 2006 Nov 15.
Article
in En
| MEDLINE
| ID: mdl-17090042
ABSTRACT
For many streptomycetes, a distinct dependence on the "bioavailability" of copper ions for their morphological development has been reported. Analysis of the Streptomyces coelicolor genome reveals a number of gene products encoding for putative copper-binding proteins. One of these appears as an unusual copper-binding protein with a lipoprotein signal sequence and a cupredoxin-like domain harboring a putative Type-1 copper-binding motif. Cloning of this gene from S. coelicolor and subsequent heterologous expression in Escherichia coli has allowed for a thorough spectroscopic interrogation of this putative copper-binding protein. Optical and electron paramagnetic resonance spectroscopies have confirmed the presence of a "classic" Type-1 copper site with the axial ligand to the copper a methionine. Paramagnetic NMR spectroscopy on both the native Cu(II) form and Co(II)-substituted protein has yielded active-site structural information, which on comparison with that of other cupredoxin active sites reveals metal-ligand interactions most similar to the "classic" Type-1 copper site found in the amicyanin family of cupredoxins. Despite this high structural similarity, the Cu(II)/(I) midpoint potential of the S. coelicolor protein is an unprecedented +605 mV vs normal hydrogen electrode at neutral pH (amicyanin approximately +250 mV), with no active-site protonation of the N-terminal His ligand observed. Suggestions for the physiological role/function of this high-potential cupredoxin are discussed.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Azurin
/
Streptomyces coelicolor
Language:
En
Journal:
J Am Chem Soc
Year:
2006
Document type:
Article
Affiliation country: