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bioRxiv · 10.1101/121335

A Shortened Version Of SecA (SecAN) Functions As The Protein-Conducting Channel For Nascent β-Barrel Outer Membrane Proteins

Jin, F.·Chang, Z.
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Abstract

Many proteins are translocated across biomembranes via protein translocons in targeting to their subcellular destinations. Hitherto, the SecYEG/Sec61 translocon, existing in prokaryotes and eukaryotes, represents the most intensively studied one. According to the current perception, both periplasmic and {beta}-barrel outer membrane proteins ({beta}-barrel OMPs) are translocated via the SecYEG translocon in bacterial cells, although direct living cell evidences remain lacking. Here, mainly via in vivo protein photo-crosslinking analysis, we revealed that the never reported membrane-integrated SecAN protein apparently functions as the translocon for {beta}-barrel OMPs. Additionally, SecAN contains a GXXXG motif known for mediating protein interactions in biomembranes, and processing of {beta}-barrel OMP precursors was severely affected in cells producing an assembly-defective SecAN variant resulted from the GXXXG motif mutations. Furthermore, SecAN was demonstrated to directly interact with the Bam complex, thus likely be a part of the supercomplex that we revealed earlier to be responsible for {beta}-barrel OMP biogenesis.

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Jin, F., Chang, Z.. 2017-03-28. A Shortened Version Of SecA (SecAN) Functions As The Protein-Conducting Channel For Nascent β-Barrel Outer Membrane Proteins. https://doi.org/10.1101/121335

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