Department of Cell and Molecular Biology
Box 596, Biomedical Center
S-751 24 Uppsala, Sweden
Telephone: 46-18-471 49 90
Ribokinase is an enzyme that
phosphorylates ribose at O5. It is present, and highly conserved, in every
organism looked at so far, from bacteria and plants to humans. The enzyme is
important both in recycling ribose released on nucleotide breakdown, as well as
in making use of exogenous sources of the sugar.
We solved the X-ray structure of the E. coli ribokinase, and showed that it is similar to another
popular enzyme, adenosine kinase. In classic kinase fashion, ribokinase undergoes a conformational change as part
of its reaction mechanism, which is illustrated here. This movie was
prepared mostly by Mark Harris.
More recent studies have looked at the two types of ribose-5-phosphate isomerases known to date.
Over the years, I have done a lot of work on the proteins of chemotaxis and transport in bacteria. We work mostly at the end with the receptors. These receptors come in two flavors: periplasmic receptors (binding proteins) and membrane receptors. Signals can start by the binding of small molecules to a specific binding protein, which then interacts with a membrane receptor. Some chemicals short-cut the process by binding to a membrane receptor directly. Either way, the signal goes across the membrane through the membrane receptor.
Ligand-free binding proteins exist primarily in an open state, while the binding of ligand favors a closed state. This ability to open and close is an important part of their correct operation with the chemotaxis and transport systems of the bacterial inner membrane.
The structures of various forms of the periplasmic binding proteins have been solved in the lab, including open and closed versions of the ribose-binding protein (RBP). These structures show that a continuum of forms exists along the conformational pathway.
From our end, the epoxide hydrolase story started with an EU network that is long finished, but has continued in more recent studies aimed at exploring the origins of substrate specificity and stereochemical outcome.
Last modified by S. Mowbray, 18 October, 2011