Selective selC-independent selenocysteine incorporation into formate dehydrogenases.

ABSTRACT: The formate dehydrogenases (Fdh) Fdh-O, Fdh-N, and Fdh-H, are the only proteins in Escherichia coli that incorporate selenocysteine at a specific position by decoding a UGA codon. However, an excess of selenium can lead to toxicity through misincorporation of selenocysteine into proteins. To determine whether selenocysteine substitutes for cysteine, we grew Escherichia coli in the presence of excess sodium selenite. The respiratory Fdh-N and Fdh-O enzymes, along with nitrate reductase (Nar) were co-purified from wild type strain MC4100 after anaerobic growth with nitrate and either 2 µM or 100 µM selenite. Mass spectrometric analysis of the catalytic subunits of both Fdhs identified the UGA-specified selenocysteine residue and revealed incorporation of additional, 'non-specific' selenocyst

SUBMITTER: Zorn M 

PROVIDER: S-EPMC3636253 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature