Role of the conserved cysteine residues of the 11.5kDa subunit in complex I catalytic properties

• Type: Article in International Scientific Journal
• Date: 2007

Authors

marques, i (Author) Other; ushakova, av (Author) Other; duarte, m (Author) ICBAS; videira, a (Author) ICBAS

Journal

Title: Journal of Biochemistry

Vol. 141

Pages: 489-493

ISSN: 0021-924X

Publisher: Oxford University Press

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 3 Citations

Scientific classification

FOS: Natural sciences

Other information

Authenticus ID: P-004-AXX

DOI: 10.1093/jb/mvm049

Abstract (EN): Mitochondrial complex I exists as a mixture of two inter-convertible forms: active (A) and de-activated (D), the latter being sensitive to SH-modifying compounds. To investigate if the conserved cysteine-rich 11.5 kDa subunit of Neurospora crassa complex I is involved in this process, we subjected the corresponding genomic DNA to site-directed mutagenesis. The four cysteine residues of the subunit were separately substituted with serine residues and the resulting proteins were independently expressed in a null-mutant strain. All of the obtained mutant strains were able to assemble a complex I with similar kinetic properties to those observed in the wild-type enzyme, indicating that none of the cysteine residues of the 11.5 kDa protein is individually relevant for the A/D transition process. Diminished amounts of assembled complex I seem to be the major effect of these specific mutations. The cysteine residues are likely important to the acquisition and stabilization of the correct 11.5 kDa protein conformation and this is reflected in the assembly/stability of complex I.

Language: English

Type (Professor's evaluation): Scientific