NirJ, a radical SAM family member of the d1 heme biogenesis cluster.
NirJ is involved in the transformation of precorrin-2 into heme d(1), although its precise role in the process has not been established. The purified protein was found to contain a 4Fe-4S centre, in line with the prediction that it belongs to the radical SAM class of enzymes. This was further confirmed by binding of S-adenosyl-L-methionine (SAM) to dithionite-reduced NirJ, which resulted in a decrease in the signal intensity and in a shift to higher field of the [4Fe-4S](1+) EPR signal. Significantly, though, this approach also led to the appearance of a small but reproducible organic radical signal that was associated with about 2% of the NirJ molecules and was affected by the incorporation of SAM deuterated at the 5' adenosyl group.
Brindley
Amanda A
AA
Department of Biosciences, University of Kent, Canterbury, Kent, UK.
Zajicek
Richard
R
Warren
Martin J
MJ
Ferguson
Stuart J
SJ
Rigby
Stephen E J
SE
D006418:Heme / Q000031:analogs & derivatives* / Q000096:biosynthesis; D008715:Methionine / Q000737:chemistry / Q000378:metabolism*
D006418:Heme; C029400:heme d1; C080647:heme d; D008715:Methionine