Published online this week in the open-access journal PLoS Biology Todd Yeates and colleagues from UCLA have investigated the mechanisms that engineer this remarkable heat resistance. By way of an elegant analysis of publicly available genome sequence and protein structure data, they answer the question: how do these thermophilic bacteria and archaea manage to maintain active, stable proteins at such high temperatures? The authors found that proteins from P. aerophilum along with some other thermophiles have many disulfide bonds (covalent bonds between two spatially proximate cysteines), which are known to improve stability.
By mapping intracellular gene sequences from 199 prokaryote genomes onto sequence-related proteins with known three-dimensional structures, they produced structural models which revealed when disulfide bonds are likely to form. A bias was found for disulfides in a set of thermophilic genomes. To prove that these predictions really do form disulfide bonds, the authors solved the structure of one protein from P. aerophilum--which was indeed stabilized by three disulfide bonds.
Disulfide bonds are more commonly formed outside or between cells in multicellular organisms. The high numbers of bonds observed in these prokaryotes challenge our ideas of how disulfide bonds form. Given the difficulty for disulfides to form in such organisms, the authors investigated which proteins are present in the disulfide-ri
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Contact: Paul Ocampo
press@plos.org
415-624-1224
Public Library of Science
22-Aug-2005