Pm. Vignais et al., HUPUV PROTEINS OF RHODOBACTER-CAPSULATUS CAN BIND H-2 - EVIDENCE FROMTHE H-D EXCHANGE-REACTION, Journal of bacteriology, 179(1), 1997, pp. 290-292
The H-D exchange reaction has been measured with the D-2-H2O system, f
or Rhodobacter capsulatus JP91, which lacks the hupSL-encoded hydrogen
ase, and R, capsulatus BSE16, which lacks the HupUV proteins, The hupU
V gene products, expressed from plasmid pAC206, are shown to catalyze
an H-D exchange reaction distinguishable from the H-D exchange due to
the membrane-hound, hupSL-encoded hydrogenase, In the presence of O-2,
the uptake hydrogenase of BSE16 cells catalyzed a rapid uptake and ox
idation of H-2, D-2, and HD present in the system, and its activity (H
-D exchange, H-2 evolution in presence of reduced methyl viologen [MV(
+)]) depended on the external pH, while the H-D exchange due to HupUV
remained insensitive to external pH and O-2. These data suggest that t
he HupSL dimer is periplasmically oriented, while the HupUV proteins a
re in the cytoplasmic compartment.