January 1, 2018.
In archaea, HP/HB cycle is essential and proceeds via the most efficient pathway different from that in the well-studied bacterial C-cycling system. 4-Hydroxybutryl-CoA dehydratese is a widespread HP/HB enzyme in archaea and contains the iron-sulfur cluster and conserved catalytic domains and residues. In anaerobic bacteria, 4HBD is also essential. Although anaerobic HBD have been structurally well studied, the role of aerobic environment in catalysis remains elusive. Here, we investigated the structure of hamarceal 4HBD from Nitrosopumilus maritimus. We present the crystal structures of high-resolution catalytically active domains of tetrameric 4HBD, in liganded form and complexed with FAD substrates. We found that 4HBD possess buried deep substrate binding clefts with dehydrogenase activities. 4HBD exhibited structural characteristics within the substrate-binding cleft similar to those in anaerobic. However, 4HBD lacked structural elements favoring substrate binding beyond the active sites, including an extra wall structure present in aerobic ones. Nevertheless, the X may compensate for this difference; a truncation containing extra C-terminal displayed activity toward insoluble polymeric substrates that was higher than those. Our observations provide the structural insights of the 4HBD dehydration.
SLAC National Accelerator Laboratory (SLAC)
The 2018 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the National Science Foundation through the Robert Noyce Program under Grant #1836335 and 1340110, the California State University Office of the Chancellor, and California Polytechnic State University in partnership with [Your lab site] and [Any other organizations pertinent to your project]. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the funders.
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