Manipulating the Length of the b Subunit F sub(1) Binding Domain in F sub(1)F sub(0) ATP Synthase from Escherichia coli

• Published in: Journal of bioenergetics and biomembranes Vol. 37; no. 2; pp. 67 - 74
• Main Authors: Bhatt, Deepa, Cole, Stephanie P, Grabar, Tammy Bohannon, Claggett, Shane B, Cain, Brian D
• Format: Journal Article
• Language: English
• Published: 01-04-2005
• Subjects: Escherichia coli
• ISSN: 0145-479X; 1573-6881
• DOI: 10.1007/s10863-005-4129-7

The peripheral stalk of F sub(1)F sub(0) ATP synthase is composed of a parallel homodimer of b subunits that extends across the cytoplasmic membrane in F sub(0) to the top of the F sub(1) sector. The stalk serves as the stator necessary for holding F sub(1) against movement of the rotor. A series of insertions and deletions have been engineered into the hydrophilic domain that interacts with F sub(1). Only the hydrophobic segment from {val-121} to {ala-132} and the extreme carboxyl terminus proved to be highly sensitive to mutation. Deletions in either site apparently abolished enzyme function as a result of defects is assembly of the F sub(1)F sub(0) complex. Other mutations manipulating the length of the sequence between these two areas had only limited effects on enzyme function. Expression of a b subunit with insertions with as few as two amino acids into the hydrophobic segment also resulted in loss of F sub(1)F sub(0) ATP synthase. However, a fully defective b subunit with seven additional amino acids could be stabilized in a heterodimeric peripheral stalk within a functional F sub(1)F sub(0) complex by a normal b subunit.