Structural Analysis of the ATP Synthase Membrane Domain

  • Girvin, Mark E. (PI)

Project: Research project

Project Details

Description

DESCRIPTION (provided by applicant): The F1F0 ATP synthase is responsible for
synthesizing the vast majority of cellular AlP. Not surprisingly, deleterious
mutations in genes of the ATP synthase lead to inherited disorders, especially
of nerves and muscles. The enzyme consists of two subcomplexes. The
water-soluble F1 contains the catalytic sites for AlP synthesis and hydrolysis.
The transmembrane F0 is responsible for proton transport. Remarkable progress
has been made in understanding the structural and mechanistic aspects of
catalysis by F1. As is always the case with membrane proteins, progress with
the Fo has been much slower. Fo comprises three types of subunits in an a1b2c10
stoichiometry. Proton translocation through Fo is hypothesized to occur at the
interface between the a-and c-subunits, beginning with a half-channel in
subunit-a, moving through the essential Asp6l of subunit-c, and concluding with
a second half-channel in subunit-a. Recent structures of subunit-c monomers in
both protonation state suggest that during proton translocation the C-terminal
helix of subunit-c rotates against subunit-a as a small "gear," driving
rotation of a ring of c-subunits relative to the static subunits, and
ultimately leading to the catalytic conformational changes in F1. This
hypothesis will be tested by: 1) solving the structure of subunit-c in its
oligomeric form, 2) determining the active site configurations of the
c-subunits during the steps of proton translocation, 3) identifying the proton
translocation pathways in subunit-a, and 4) determining how access of the
active site Asp61 residue of subunit-c is limited to one side of the membrane
at a time.

The sample conditions and NMR methodologies developed to accomplish these aims
will have general application to studying membrane protein structure by NMR.
Membrane proteins are responsible for transmembrane signaling, energy
transduction, and ion and metabolite transport. These proteins are important in
infectious disease, genetic disorders, and cancer. Despite their importance,
and the need for structure to understand their function, few such structures
are available.
StatusFinished
Effective start/end date1/1/978/31/06

Funding

  • National Institute of General Medical Sciences: $321,527.00

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