<p>Members of this family represent the alpha subunit of the multifunctional enzyme complex of the fatty acid degradation cycle, which plays a minor role in aerobic beta-oxidation of fatty acids. The FadJI complex is necessary for anaerobic growth on short-chain acids with nitrate as an electron acceptor. Activities include: enoyl-CoA hydratase (<db_xref db="EC" dbkey="4.2.1.17"/>), 3-hydroxyacyl-CoA dehydrogenase (<db_xref db="EC" dbkey="1.1.1.35"/>), and 3-hydroxybutyryl-CoA epimerase (<db_xref db="EC" dbkey="5.1.2.3"/>). A representative is the <taxon tax_id="562">Escherichia coli</taxon> FadJ protein (also named YfcX) (<db_xref db="SWISSPROT" dbkey="P77399"/>). This entry excludes FadB of <db_xref db="INTERPRO" dbkey="IPR012799"/>.</p>