SecA, an essential component of the secretory machinery of Escherichia coli, exists as homodimer - PubMed (original) (raw)

SecA, an essential component of the secretory machinery of Escherichia coli, exists as homodimer

M Akita et al. Biochem Biophys Res Commun. 1991.

Abstract

Size exclusion chromatography of the cytosolic fraction of SecA-overproducing cells of Escherichia coli suggested that SecA, an essential component of the secretory machinery, exists as an oligomer. The subunit structure of SecA was then studied using a purified specimen. Estimation of the molecular mass by means of ultracentrifugation and chemical crosslinking analysis revealed that SecA exists as a homodimer. The purified SecA was denatured in 6 M guanidine-HCl and renatured to a dimer, which was fully active in terms of translocation, even in the presence of 1 mM dithiothreitol. It is suggested that the dimeric structure is not critically maintained by disulfide bonding between the two subunits, each of which contains four cysteine residues.

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