Identification and evolution of dual-topology membrane proteins

• Integral membrane proteins are generally believed to have unique membrane topologies. However, it has been suggested that dual-topology proteins that adopt a mixture of two opposite orientations in the membrane may exist. Here we show that the membrane orientations of five dual-topology candidates identified in Escherichia coli are highly sensitive to changes in the distribution of positively charged residues, that genes in families containing dual-topology candidates occur in genomes either as pairs or as singletons and that gene pairs encode two oppositely oriented proteins whereas singletons encode dual-topology candidates. Our results provide strong support for the existence of dual-topology proteins and shed new light on the evolution of membrane-protein topology and structure.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

Biochemistry

biokemi

Publication and Content Type

ref (subject category)

art (subject category)