1 research outputs found
The Manganese Ion of the Heterodinuclear Mn/Fe Cofactor in <i>Chlamydia trachomatis</i> Ribonucleotide Reductase R2c Is Located at Metal Position 1
The essential catalytic radical of Class-I ribonucleotide
reductase
is generated and delivered by protein R2, carrying a dinuclear metal
cofactor. A new R2 subclass, R2c, prototyped by the <i>Chlamydia
trachomatis</i> protein was recently discovered. This protein
carries an oxygen-activating heterodinuclear Mn(II)/Fe(II) metal cofactor
and generates a radical-equivalent Mn(IV)/Fe(III) oxidation state
of the metal site, as opposed to the tyrosyl radical generated by
other R2 subclasses. The metal arrangement of the heterodinuclear
cofactor remains unknown. Is the metal positioning specific, and if
so, where is which ion located? Here we use X-ray crystallography
with anomalous scattering to show that the metal arrangement of this
cofactor is specific with the manganese ion occupying metal position
1. This is the position proximal to the tyrosyl radical site in other
R2 proteins and consistent with the assumption that the high-valent
Mn(IV) species functions as a direct substitute for the tyrosyl radical