Biology subjects

von Heijne, G.

Publications and source records attributed to von Heijne, G..

2 recordsLinked to original sources

bioRxiv2018

Forces on nascent polypeptides during membrane insertion and translocation via the Sec translocon

During ribosomal translation, nascent polypeptide chains (NCs) undergo a variety of physical processes that determine their fate in the cell. Translation arrest peptide (AP) experiments are used to measure the external pulling forces that are exerted on the NC at different lengths during translation. To elucidate the molecular origins of these forces, a recently developed coarsegrained molecular dynamics (CGMD) is used to directly simulate the observed pulling-force profiles, thereby disentangling contributions from NC-translocon and NC-ribosome interactions, membrane partitioning, and electrostatic coupling to the membrane potential. This combination of experiment and theory reveals mechanistic features of Sec-facilitated membrane integration and protein translocation, including the interplay between transient interactions and conformational changes that occur during ribosomal translation to govern protein biogenesis.

biophysics↗

bioRxiv2017

Stable Membrane Topologies Of Small Dual-Topology Membrane Proteins

The topologies of -helical membrane proteins are generally thought to be determined during their cotranslational insertion into the membrane. It is typically assumed that membrane topologies remain static after this process has ended. Recent findings, however, question this static view by suggesting that some parts of, or even the whole protein, can reorient in the membrane on a biologically relevant time scale. Here, we focus on anti-parallel homo-or hetero-dimeric Small Multidrug Resistance proteins, and examine whether the individual monomers can undergo reversible topological inversion (flip-flop) in the membrane until they are trapped in a fixed orientation by dimerization. By perturbing dimerization using various means, we show that the membrane topology of a monomer is unaffected by the presence or absence of its dimerization partner. Thus, membrane-inserted monomers attain their final topologies independently of dimerization, suggesting that wholesale topological inversion is an unlikely event in vivo.

biochemistry↗