Molecular genetic studies on the cytochrome bc(1) complex of Rhodobacter sphaeroides
Yun, Chang-Hyon
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/21737
Description
Title
Molecular genetic studies on the cytochrome bc(1) complex of Rhodobacter sphaeroides
Author(s)
Yun, Chang-Hyon
Issue Date
1990
Doctoral Committee Chair(s)
Gennis, Robert B.
Department of Study
Biophysics and Computational Biology
Discipline
Biophysics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Molecular
Biophysics, General
Language
eng
Abstract
The ubiquinol:cytochrome c$\sb2$ oxidoreductase ($bc\sb1$ complex) is a central component of the mitochondrial respiratory chain as well as the respiratory and photosynthetic system of many prokaryotes. The fact that the $bc\sb1$ complex from Rb. sphaeroides has been extensively studied, plus the ability to genetically manipulate this organism, makes this an ideal system for site-directed mutagenesis to address questions relating to the structure and function of the $bc\sb1$ complex.
In this thesis, the cloning and complete sequence of the fbc operon from Rb. sphaeroides is reported. As in other bacteria, this operon contains three genes, encoding the Rieske FeS subunit, the cytochrome b subunit, and the cytochrome $c\sb1$ subunit. Recombination techniques were used to delete the fbc operon from the chromosome, resulting in strains that are incapable of growing photosynthetically. Photosynthetic growth is restored by complementing in trans by the fbc operon on a plasmid.
The topology of the b cytochrome subunit has been tested by constructing the fbcB-phoA gene fusions. The results of the fusion were consistent with the eight-span model that has recently been widely accepted.
The main focus of this thesis is the structure and function relationship of the b cytochrome subunit studied by site-directed mutagenesis of a number of highly conserved amino acid residues. It is shown that the four histidines that are conserved in all the b cytochromes are essential residues for the functioning of the complex, and probably are the ligands for the two b hemes. Strains carrying mutations on these histidines have lost either both b hemes or the high-potential b heme. In addition, several of highly conserved amino acids, e.g. Gly-48, Gln-58, Ser-102, Phe-104, and Pro-202, whose probable importance had previously been suggested, were altered and the resulting strains were characterized.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
