Dissecting the conformational complexity and mechanism of a bacterial heme transporter.

Iron-bound cyclic tetrapyrroles (hemes) are redox-active cofactors in bioenergetic enzymes. However, the mechanisms of heme transport and insertion into respiratory chain complexes remain unclear. Here, we used cellular, biochemical, structural and computational methods to characterize the structure and function of the heterodimeric bacterial ABC transporter CydDC.

Shuffled ATG8 interacting motifs form an ancestral bridge between UFMylation and autophagy.

UFMylation involves the covalent modification of substrate proteins with UFM1 (Ubiquitin-fold modifier 1) and is important for maintaining ER homeostasis. Stalled translation triggers the UFMylation of ER-bound ribosomes and activates C53-mediated autophagy to clear toxic polypeptides. C53 contains noncanonical shuffled ATG8-interacting motifs (sAIMs) that are essential for ATG8 interaction and autophagy initiation.