Characterisation of the last Fe-S cluster-binding subunit of Neurospora crassa complex I

We have cloned cDNAs encoding the last iron-sulphur protein of complex I fr om Neurospora crassa. The cDNA sequence contains an open reading frame that codes for a precursor polypeptide of 226 amino acid residues with a molecu lar mass of 24 972 Da. Our results indicate that the mature protein belongs probably to the peripheral arm of complex I and is rather unstable when no t assembled into the enzyme. The protein is highly homologous to the PSST s ubunit of bovine complex I, the most likely candidate to bind iron-sulphur cluster N-2. All the amino acid residues proposed to bind such a cluster ar e conserved in the fungal protein. (C) 1999 Elsevier Science B.V. All right s reserved.