RT Journal Article
SR Electronic
T1 Molecular analysis of human Ero1 reveals novel regulatory mechanisms for oxidative protein folding
JF Life Science Alliance
JO Life Sci. Alliance
FD Life Science Alliance LLC
SP e201800090
DO 10.26508/lsa.201800090
VO 1
IS 3
A1 Antti Moilanen
A1 Kati Korhonen
A1 Mirva J Saaranen
A1 Lloyd W Ruddock
YR 2018
UL https://www.life-science-alliance.org/content/1/3/e201800090.abstract
AB Oxidative protein folding in the ER is driven mainly by oxidases of the endoplasmic reticulum oxidoreductin 1 (Ero1) family. Their action is regulated to avoid cell stress, including hyperoxidation. Previously published regulatory mechanisms are based on the rearrangement of active site and regulatory disulfides. In this study, we identify two novel regulatory mechanisms. First, both human Ero1 isoforms exist in a dynamic mixed disulfide complex with protein disulfide isomerase, which involves cysteines (Cys166 in Ero1α and Cys165 in Ero1β) that have previously been regarded as being nonfunctional. Second, our kinetic studies reveal that Ero1 not only has a high affinity for molecular oxygen as the terminal acceptor of electrons but also that there is a high cooperativity of binding (Hill coefficient >3). This allows Ero1 to maintain high activity under hypoxic conditions, without compromising cellular viability under hyper-hypoxic conditions. These data, together with novel mechanistic details of differences in activation between the two human Ero1 isoforms, provide important new insights into the catalytic cycle of human Ero1 and how they have been fine-tuned to operate at low oxygen concentrations.