A novel respiratory complex in Desulfovibrio vulgaris

ITQB PhD Seminars

Title: A novel respiratory complex in Desulfovibrio vulgaris Hildenborough

Speaker: Sofia Venceslau 

Laboratory: Microbial Biochemistry

Abstract:

Membrane proteins are essential in vital cellular processes of all organisms, including the respiratory mechanism and they represent ca. 30% of the genomic information.

A new class of bacterial membrane oxidoreductases was found, and was named MFI (for Molybdopterin, FeS and Integral membrane subunit), and then sub grouped in MFIc for the class with four subunits, and in MFIcc for the group with a bigger complex with six subunits. The MFIcc class was already reported in Chloroflexus aurentiacus and Rhodothermus marinus (here in ITQB), and was suggested to be an alternative complex III. The operon for the smaller MFIc complex is present in the genomes of a small group within the Deltaproteobacteria, all sulfate-reducing bacteria (SRB). This work describes the first example of a membrane bound complex from the MFIc group in Desulfovibrio vulgaris Hildenborough. The complex is composed by three periplasmic subunits (a multihemic protein anchored to the membrane, an FeS protein and a protein that is annotated as a molybdoreductase like subunit) and one integral membrane protein.
Several membrane complexes have been isolated from the SRB in the last years, but there are still some points of the energy metabolism to be established, namely in the donors and receptors of the electron transfer flow across the membrane. The function of this new respiratory complex will be adressed, and since it is distinct from the MFIcc, we propose to name it as Qrc (for Quinone reductase complex) since it reduces quinones to quinols, which is the opposite function for the MFIcc. In agreement with this result the electron donors to the Qrc have to be present in the periplasm, and in fact electron transfer assays indicate hydrogenases and formate dehydrogenases as possible ones.

Short CV:
2004: Graduated in Applied Chemistry at Universidade Nova de Lisboa, Portugal
2005-2006: Research student at Microbial Biochemistry Lab under the supervision of Prof. Inês Pereira
2007: PhD fellowship by Fundação para a Ciência e Tecnologia at Microbial Biochemistry Lab under the supervision of Dra. Inês Pereira.